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  • 1. VIROLOGY
  • 2. 1796:Edward Jenner (1749-1823) used cowpox to vaccinate against smallpox was the first person to deliberately vaccinate against any infectious disease used a preparation to elicit an immune response. Variolation – infecting people with smallpox – to protect them from the worst type of the disease
  • 3. 1885: Louis Pasteur (1822-1895) experimented with rabies vaccination using the term "virus" to describe the agent "virus" and "vaccination" (in honor of Jenner)
  • 4. 1886: John Buist Scottish pathologist stained lymph from skin lesions of a smallpox – "elementary bodies" – he thought were the spores of micrococci – smallpox virus particles
  • 5. 1892: Dmiti Iwanowski (1864- 1920) described the first "filterable" infectious agent – tobacco mosaic virus (TMV)  smaller than any known bacteria  first to discriminate between viruses and other infectious agents
  • 6. 1898: Martinus Beijerinick (1851- 1931) – extended Iwanowskis work with TMV – developed the concept of the virus as a distinct entity
  • 7. Freidrich Loeffler (1852-1915) and Paul Frosch (1860-1928) – demonstrated that foot and mouth disease – first to prove that viruses could infect animals as well as plants
  • 8. 1900: Walter Reed (1851-1902) demonstrated that yellow fever is spread by mosquitoes first to show that viruses could be spread by insect vectors such as mosquitoes1908: Karl Landsteiner (1868- 1943) and Erwin Popper proved that poliomyelitis: virus proved that viruses could infect humans as well as animals
  • 9. 1911: Francis Peyton Rous (1879- 1970) demonstrated that a virus (Rous sarcoma virus) can cause cancer in chickens first person to show that a virus could cause cancer
  • 10. 1915: Frederick Twort (1877-1950) discovered viruses infecting bacteria1917: Felix dHerelle (1873-1949) – independently discovered viruses of bacteria – coins the term bacteriophage
  • 11. 1938: Max Theiler (1899-1972) developed a live attenuated vaccine against yellow fever safe and effective that it is still in use today!1940: Helmuth Ruska (1908-1973) used an electron microscope: virus particles direct visualization of virions
  • 12. 1941: George Hirst demonstrated that influenza virus agglutinates red blood cells viruses could be counted1945: Salvador Luria (1912-1991) and Alfred Hershey (1908-1997) demonstrated that bacteriophages mutate antigenic variation in viruses.
  • 13. 1957: Alick Isaacs and Jean Lindemann discovered interferon – first cytokines to be studied in detailCarleton Gajdusek – proposed: a "slow virus" is responsible for the prion disease kuru – kuru is similar to that of scrapie – kuru can be transmitted to
  • 14. 1961: Sydney Brenner, Francois Jacob, and Matthew Meselson demonstrated that bacteriophage T4 uses host cell ribosomes – to direct virus protein synthesis – fundamental molecular mechanism of protein translation.
  • 15. 1963: Baruch Blumberg discovered hepatitis B virus (HBV) developed the first vaccine against the HBV – first vaccine against cancer1989: Hepatitis C virus (HCV) nonA, nonB hepatitis first infectious agent to be identified by molecular cloning of the genome
  • 16.  Sending Specimens to the Laboratory –Right specimen –Taken at the right time –Stored and transported immediately
  • 17. Specimens for viral isolation or Ag detectionRespiratory Infection Nasal or throat  swabs, postnasal washingsGastrointestinal infxn FecesVesicular rash Vesicular fluid, throat swab, fecesHepatitis Serum, fecesCNS CSF, throat swab, fecesAIDS Unclotted blood
  • 18. SPECIMENS: Blood serum – syringe – vacutainer Swabs – skin lesions – throat – transport medium  antibacterial  antifungal
  • 19.  Vesicle fluid – tip of a scalpel blade – large needle – spread on a slide CSF – dry sterile container Feces – dry sterile container – rectal swab
  • 20.  Storage: – secure plastic bags – labeled – transported ASAP – 4oC: overnight Request forms: – date on onset of disease – clinical signs – suspected diagnosis
  • 21. Laboratory Diagnosis for viral Infections
  • 22. 3 Basic categories of methodsused in the Diagnosis of virus infections Direct Examination Indirect examination Serology
  • 23. Direct ExaminationClinicalspecimen examined directly for presence of virus particles, virus antigens, viral nucleic acids and virus-induced histological changes
  • 24. Direct ExaminationClinical specimen –virus particles –virus antigens –viral nucleic acids –virus-induced histological changes
  • 25. Direct ExaminationMain advantage: short length of time required for resultResults available the same dayspecific antiviral chemotherapy
  • 26. Direct ExaminationAutomated molecularbiology techniquesavailable: 1. PCR-based amplicor system 2. Abbott LCR system 3. Chiron branched DNA system
  • 27. Direct Examination Wave of the future:DNA chip technology detect viruses from clinical specimens tell viral load determine antiviral agent the virus is sensitive to
  • 28. Indirect ExaminationVirus amplification: growing in tissue culture, eggs or animalsGrowing virus: changes cytopathic effect (CPE) ability to hemadsorbIdentity of virus confirmed by: virus neutralization Immunofluorescence complement fixation electron microscopy
  • 29. Indirect ExaminationDisadvantage of virus culture: long time required for CPE ability to hemadsorb to become apparentMay take a few days to a fewweeksVirus culture sensitivity: low anddepends on quality of clinicalspecimen receivedNot applicable to viruses that aredifficult or can not be cultivated
  • 30. SEROLOGYRemains the bulk of work carriedout by a routine diagnosticlaboratory Complement fixation test hemagglutination-inhibition enzyme linked immunoassay Radioimmunoassay particle agglutination Immunofluorescence single radial hemolysis western blot
  • 31. SEROLOGYSensitivity and specificity rates varyMost techniques will detect allclasses of antibodySome assays like RIA, EIA and IFcan be made to detect one specificclass IgM, IgG, IgAVirus infections usually diagnosedby serology: * hepatitis A, B and C
  • 32. DIFFICULT VIRUSESViral infections of the Centralnervous system infection in immunocompetent hosts infection caused by HIV and opportunistic infectionsViral pneumoniasViral skin infectionsEmerging viral infections
  • 33. Viral infections of the CNS Most cases of acute encephalitis in immunocompetent hosts due to: * HSV-1 and HSV-2 * EBV * HHV-6 and HHV-7 Among immunocompromised individuals: * CMV * VZV
  • 34. Viral infections of the CNSDiagnosis revolutionized by availability of cerebrospinal fluid (CSF) polymerase chain reaction analysisPCR allows rapid, specific and sensitive diagnosis
  • 35. Viral infections of the CNS CSF-PCR instead of brain biopsy – Dx standard for HSV encephalitis – mild or atypical cases 16-25% of cases HSV PCR analysis of CSF –monitoring adequacy of therapy –14day treatment with acyclovir  negative PCR Prognosis: – Determination of number of viral DNA copies
  • 36. Viral infections of the CNS EBV semi-quantitative PCR –significantly higher: active EBV infection – latently infected patients seropositive: LOWER positive EBV PCR in CSF –sensitive and specific primary CNS lymphoma in patients with AIDS CNS mass lesions
  • 37. Viral infections of the CNS HHV 6 and HHV 7 –Almost all children –PCR review of CSF specimens from patients initially suspected to have HSV encephalitis found HHV 6 DNA in ~ 7% of specimens – suggests HHV 6 may be an important cause of sporadic focal encephalitis
  • 38. Viral infections of the CNS Using CSF RT-PCR analysis –most cases (85-95%) of acute viral meningitis  enteroviruses Signs and symptoms indicative of encephalitis rather than meningitis develop in ~ 3% of patients Patients with agammaglobulinemia are at risk for chronic enteroviral meningoencephalitis
  • 39. Viral Pneumonias Causes in adults: * Adenovirus * Influenza A & B * CMV * Measles * HSV * Parainfluenza virus * RSV * VZV Causes in children * Influenza A & B * Measles * Parainfluenza * RSV
  • 40. Diagnostic techniques for herpesvirus infectionsVirus Cytologic Viral Antigen Gene evaluation culture detection ampli- ficationHSV Cowdry CPE IFA PCR Type A SVA ELISA bodiesVZV Cowdry CPE IFA MRT-PCR Type A bodiesCMV “owl’s CPE IFA MRT-PCR eye” cells SVA ELISA
  • 41. Diagnostic techniques for herpesvirus infectionsVirus Cytologic Viral Antigen Gene evaluation culture detection ampli- fication Highly CPE IFA MRT-PCRRSV eosinophilic intracytoplas SVA ELISA mic inclusionsPara Large cells HA IFA MRT-PCR with singleinfluenza nucleus & SVA ELISA multiple small eosinophilic inclusionsMeasles HA IFA ELISA
  • 42. Diagnostic techniques for viral infectionsInfluenz HA IFAa virus SVA ELISAAdeno Intra- CPE IFA MRT-virus nuclear SVA ELISA PCR inclusions
  • 43. Herpes virus skin infection Diagnosis Tzanck preparation : –used to rapidly determine presence of HSV or VZV –does not distinguish between these 2 viruses Stains : Giemsa,Wright’s, methylene blue Characteristic multinucleated giant cells – inexpensive, efficient provisional diagnosis
  • 44. Herpes virus skin infection Diagnosis HSV tissue culture: using monoclonal antibodies, requires only 24 hours –sensitive test but expensive Polymerase chain reaction –expensive Serology not very useful – general population has antibodies to herpes simplex
  • 45. Emerging Viral Infections Acute Hemorrhagic fever syndromes: – Ebola and Marburg v – Hantavirus – Arena virus Other viral encephalitis agents: – Nipah virus (previously unknown paramyxovirus)
  • 46.  Labtesting currently available only at CDC: –antigen detection – IgM antibody detection –isolation in cell culture –visualization by electron microscopy – immunohistochemical techniques –RT-PCR
  • 47. Emerging Viral Infections Many of these “emerging” viral infections are thought to pose a serious risk as biologic weapons Rapid diagnostics should be made available worldwide in order to detect as rapidly as possible both justified and unjustified suspects of HF and attacks by other “biological weapons”
  • 48. Emerging Viral Infections SARS –Severe acute respiratory syndrome –Killer pneumonia Cause has yet to be identified Laboratory tests found two types of virus: –paramyxovirus –corona virus A rapid diagnostic test should come soon
  • 49. SUMMARYDespite enhancedlaboratory techniques suchas viral culture, rapidantigen detection and geneamplification, a confidentdiagnosis of viralpneumonia continues to bea CHALLENGE
  • 50. SUMMARYThe non-specific nature of clinical characteristics & the extreme sensitivity of lab techniques make the diagnosis difficult, even when a viral agent is detected
  • 51. SUMMARYUnderstanding the limitations of these technological advances and the use of histopathological techniques can greatly enhance a skilled clinician’s ability to make an accurate diagnosis
  • 52. ADENOVIRUS
  • 53. ADENOVIRUSDNA viruses first isolatedfrom adenoidal tissue in1953
  • 54. ADENOVIRUSFamily AdenoviridaeGenus Mastadenovirus
  • 55. Transmission electron micrograph of adenovirus Source- PHIL, CDC
  • 56. ADENOVIRUS - Classification• Subdivided into 6 subgroups based on• hemagglutination (A-F)• Human pathogens belong to 49 serotypes• Common serotypes:- 1-8, 11, 21, 35, 37, 40• Enteric Adenoviruses belong to subgroup F
  • 57. ADENOVIRUS - Structure Non-enveloped DNA virus 70-90 nm in size Linear ds DNA genome with core proteins
  • 58. ADENOVIRUS EM APPEARANCE
  • 59. ADENOVIRUS - Ultrastructure Icosahedral capsid with 252 capsomeres (12 pentons at vertices and 240 hexons) Each penton has a fibers with terminal knob projecting from it
  • 60. Adenovirus- 3 D structure
  • 61. Adenovirus - EM appearanceNote- projecting fibers and terminal knob
  • 62. ADENOVIRUS-Ultrastructure
  • 63. ADENOVIRUS STRUCTURE
  • 64. Structure
  • 65. Pathogenesis and Replication• Infects mucoepithelial cells of respiratory, GI and GU tracts• Enter via epithelium, replicate and spread to lymphoid tissue• Viremia occurs• Secondary involvement of
  • 66. Pathogenesis and Replication (contd.) Fiber protein determines target cell specificity and attachment Viral DNA enters host cell nucleus Virus replicates in cytoplasm
  • 67. Adenovirus- replication
  • 68. Replication (contd.)• Early and late phases ofreplication• Errror-prone process• Inclusion bodies in nucleus
  • 69. ADENOVIRAL INCLUSION BODIES
  • 70. Types of infection Lytic Latent/occult Oncogenic Transformation
  • 71. Types of infection Lytic Results in cell death; seen in mucoepithelical cells Latent/occult Virus remains in host cell; seen in lymphoid tissue, Groups B and C Oncogenic Transformation Uncontrolled cell growth and replication occur; seen with Group A viruses in hamsters
  • 72. Adenovirus Used as VECTORS to transfer desired genetic material into cells e Viral genome is relatively easily manipulated in vitro Efficient expression of inserted DNA in recipient cell
  • 73. Adenovirus- Properties Stable in the environment Relatively resistant to disinfection (Alcohol, chlorhexidine, detergents) Stable in GI tract- can withstand low pH, bile acids and proteolytic enzymes
  • 74. Time-course of infection Incubation period- 2-14 days Infective period continues for weeks Intermittent and prolonged rectal shedding Secondary attack rate within families up to 50%
  • 75. Timecourse - Respiratory infection Source- Medical Microbiology- Murray, Rosenthal, Kobayshi and Pfaller
  • 76. EPIDEMIOLOGYEndemic, epidemic and sporadic infectionsMany infections are subclinical
  • 77. EPIDEMIOLOGY-contd. ”Tip of the iceberg phenomenon” Classical disease presentation Mild clinical disease Asymptomatic infection but infectivity (+)
  • 78. Epidemiology of Adenoviral Infections (source-centers for disease control and prevention)
  • 79. EPIDEMIOLOGYOutbreaks noted in military recruits,swimming pool users, hospitals,residential institutions, day care settings
  • 80. EPIDEMIOLOGY-transmission Prolonged infective period (weeks) Intermittent and prolonged rectal shedding Stable in the environment
  • 81. TRANSMISSION• Droplets• Fecal-oral route• Direct and through poorly chlorinated water• Fomites
  • 82. CLINICAL SYNDROMES• Respiratory• Eye• Genitourinary• Gastrointestinal• Others
  • 83. Acute Respiratory Disease (LRI) Fever Tracheobronchitis Pneumonia Childrenand adults Epidemics in military recruits Types 4 and 7 most frequently
  • 84. Acute Respiratory Disease
  • 85. Pharyngoconjunctival fever Headache, fever, malaise Conjunctivitis and Pharyngitis Cervical adenopathy, rash and diarrhea also Main adenovirus types: 3, 4, 7, 14 Epidemics in summer months Contaminated water in swimming pools, fomites
  • 86. Adenoviral Infections of the eye Epidemic Keratoconjunctivitis (EKC) Acute follicular conjunctivitis Pharyngoconjunctival fever
  • 87. Adenoviral Infections of the eye
  • 88. Epidemic Keratoconjunctivitis Incidence in summer Conjunctivitis usually followed by keratitis Headache Pre-auricular lymphadenopathy Types 8, 19, 37 Nosocomial spread by fomites, hands, ophthalmologic equipment, medications
  • 89. Gastrointestinal Infections Types 40, 41 Age <4 years Spread via fecal-oral route Year round
  • 90. Gastrointestinal Infections- (contd.) Incubation period 3-10 days Diarrhea lasts for 10-14 days Fever Also, intussusception, mesenteric adenitis, appendicitis
  • 91. INTUSSUSCEPTION
  • 92. ADENOVIRAL INFECTIONS- Genitourinary systemAcute hemorrhagic cystitis fever, dysuria, hematuria Types 11, 7, 4, 21, 1 More common in boysOthers Orchitis, nephritis, cervicitis with ulcerated vesicular lesions Types 2, 19, 37
  • 93. Other Infections due to Adenovirus•Myocarditis•Pericarditis•Meningitis•Rash•Arthritis
  • 94. Adenovirus infections in Immunocompromised hosts Disseminated, severe and often fatal infections Due to new infection or reactivation of latent virus Prolonged infections with prolonged viremia and viral shedding Necrotizing pneumonia, hepatitis, rash, DIC, CNS involvement
  • 95. Adenovirus infection in the immunocompromised
  • 96. DIAGNOSIS Variety of clinical specimens depending on clinical syndrome-NP, conjunctival, stool, urine, tissue, etc. Transport in viral transport media Isolation from pharyngeal site correlates better with current clinical infection
  • 97. Methods for diagnosis Culture in HeLa, HEK cell lines Shell vial cell culture DFA PCR, nucleic acid probes EM and Immune EM
  • 98. Diagnosis- Enteric adenoviruses Isolation requires special media- Graham 293 ELISA for rapid detection is available
  • 99. Prevention Good handwashing Contact precautions Chlorination of water Disinfection or sterilization of ophthalmologic equipment Use of single dose vials Oral vaccine- restricted
  • 100. HIV and AIDSThe cellular and immunological picture - The course ofthe disease
  • 101. HIV and AIDSThe cellular and immunological picture - The courseof the disease
  • 102. HIV and AIDSThe cellular and immunological pictureThe course of the disease1. Acute Infection • High virus titer • Mild symptoms • Fall in CD4+ cells but recovers • Rise in CD8+ cells but recovers • A high virus titer (up to 10 million Macrophages bring HIV into the body if se viruses per ml blood)
  • 103. HIV and AIDS 2. A strong immune responseVirus almost disappears from circulation• Good cytoxic T cell response• Soluble antibodies appear later against bothsurface and internal proteins• Most virus at this stage comes from recentlyactivated (dividing) and infected CD4+ cells
  • 104. HIV and AIDS 3. A latent stateLatency of virus and of symptoms• Virus persists in extra-vasculartissues• Lymph node dendritic cells• Resting CD4+ memory cells (last averylong time - a very stable population ofcells) carry provirus
  • 105. HIV and AIDS• 10 billion HIV particles per day• Virus half life 5.7 hours• 100-10 million virions per ml blood (set point)• Small minority of T4 cells are infected• Virus found in lymph nodes
  • 106. HIV and AIDS 4. The beginning of diseaseMassive loss of CD4+ cells• CD4+ cells are the targets of the virus• Cells that proliferate to respond to the virus are killed by it• Dendritic cells present antigen and virus to CD4 cells• Epitope variation allows more and moreHIV toescape from immune response just as
  • 107. HIV and AIDS 5. Advanced disease - AIDSCD8+ cells destroy moreCD4+ cells• CD4 cell loss means virus andinfected cells no longer controlled• As CD4+ cells fall below 200per cu mmvirus titer rises rapidly andremaining immune response
  • 108. HIV and AIDS Good correlation betw number of HIV particle measured by PCR an progression to disease
  • 109. HIV and AIDS Viral load predicts survival time
  • 110. HIV and AIDS CD4 cell count is not good predictor of progression to diseas
  • 111. HIV and AIDS CofactorsNot all cases of Kaposi’s are associated with HIVNot all HIV infected persons suffer from Kaposi’s20% of homosexual HIV+ males get Kaposi’sFew IV drug users or hemophiliacs get Kaposi’s Kaposi’s sarcoma associated herpes virus Human herpes virus-8
  • 112. HIV and AIDS Three Views of AIDS Gallo: Infection by HIV is sufficient to cause AIDSMontagnier: HIV may be harmless in the absence of other co-factorsDuesberg / Mullis: HIV is too silent to be the etiologic agent ofAIDS. It is a much maligned by-standerSo far it seems that >50% of HIV-infected persons haveprogressed to AIDSThere is NO strong evidence there is any other infectiousagent involved than HIV
  • 113. HIV - The Virus RetrovirusMembrane: host derived Three genes GAG – POL – ENV
  • 114. HIV - The Virus RetrovirusTwo glycoproteins: gp160 gp120 and gp41gp41 is fusogen that spans the membranesugars vaccine problem ENV gene
  • 115. HIV - The Virus Retrovirus Group-Specific Antigensp17: inner surface - myristoylatedp24: nucleocapsidp9: nucleocapsid associated with RNAGAG gene Polyprotein
  • 116. HIV - The Virus Enzymes Retrovirus• Polymerase (reversetranscriptase – RNAdependent DNApolymerase)• Integrase • POL gene• Protease (cuts Polyproteinpolyproteins)
  • 117. The Genome of HIVThree structural genesLTRsExtra open reading frames are clue to latency
  • 118. HIV - The Virus
  • 119. HIV - The Virus Life History A retrovirus • Latency • Specific destruction of CD4+ cells
  • 120. HIV - Life History • Fusion at ambient pH • No need for entry into lysosomes •Profound significance Syncytia for AIDS progression: Spread from cell to cell Profound significance
  • 121. HIV - Life History Entry into the cell T4 (CD4+) cells are major target Human HeLa Human Cell transfected HeLa Cell with CD4 antigenNOT INFECTED INFECTED But NOT the whole answer since this does not happen if CD4 is transfected in
  • 122. HIV - Life History Why do CD4-transfected human cell but CD4-transfected mouse cells do Human cells must possess a co-factor for infection that mouCo-ReceptorsCD8+ CellsMIP-1 alpha MIP-1 beta RANTESChemokines
  • 123. HIV - Life History HIV chemoki Mutant CD4 ne CCR5 CCR5 CCR5 CD4 CD4 macrophageChemokine receptors are necessary co-recep
  • 124. HIV and AIDSSome people do not get AIDSLong term survivorsExposed uninfected persons The chemokine receptor story
  • 125. HIV and AIDSCo-receptors and HIV infection• CCR5 is a chemokine receptor• Cells with homozygous mutant CCR5 molecules are notinfected by HIV1 in 100 CaucasiansNo Africans• Persons with heterozygous mutant CCR5 moleculesprogress to AIDS more slowly
  • 126. HIV and AIDSCo-receptors• 25% of long term survivors are CCR5 or CCR2mutants (deletions)• The same CCR5 mutation (called “delta 32”) isthought to be the mutation that rendered somepeople immune to the plague in the middleages • Many other chemokine receptors
  • 127. HIV and AIDS Long term non-progressers People who have been infected with HIV for more than seven years that have stable CD4+ cell counts above 600 per cu mm with no symptoms and no chemotherapy Many have produced a very good immune response to the virus
  • 128. HIV and AIDS• Nairobi prostitutesClient infection rate more than 25%• Rare HLA antigens• Associations between resistance to infection and theirclass I and class II MHC (HLA) haplotypes
  • 129. HIV - Life HistoryHIV is a retrovirusIt carries with it: • Reverse transcriptase HIV genes • Integrase GAG POL • Protease ENV • tRNA primer HIV has no oncogene but could still be oncogenic vaccine problem
  • 130. HIV - Life History Latency – Cellular – The problem of memory T4 cells Only activated T4 cells can replicate virus Most infected T4 cells are rapidly lyzed but are replaced Some T4 cells revert to resting state as memory cells wh Memory T4 cells cannot replicate the virus unless they b Clinical LatencyHIV infection is not manifested as disease for years
  • 131. Dynamics of CD4 T cells in an HIV infection Cell death Chronically- apoptosis etc infected memory T Return to cells with Infection restingUninfected state provirusactivated LongT cell Reactivation lived! Uninfected Cell death Long unactivated memory immune lived! Adapted from Saag and Kilby T cell pool destruction Nat Med 5: 609, 1999
  • 132. Long tern latent HIV Immune responseT4 resting T4 activated It may be impossible to cure the patient o Even if combination therapy stops HIV re HIV
  • 133. Inexorable decline of CD4+ T4 cellsWhy do allof the T4cellsAt earlydisappear?stages ofinfectiononly 1 in10,000 cellsis infected Of great importance to therapeutic strategy
  • 134. Virus destroys the cell as a result of budding But few cells are infected: Early stage of infection 1:10,000 Late 1:40 Why do all T4 cells1. PUNCTURED disappear?MEMBRANE
  • 135. Why do all T4 cells disappear? - 2 But syncytia not commonInfected CD4 Cellscell Most T4 cells FuseGp120 are not HIV+positive Could “sweep up” UninfectedKilling of CD4 cells CD4 cell uninfected2. Syncytium Gp120 cellsFormation negative
  • 136. Why do all T4 cells disappear? Cytotox ic T cell Killing of CD4 cells 3. Cytotoxic T cell-BUT: Most mediated lysiscells are
  • 137. Killing ofCD4+ cells4. Binding of freeGp120 to CD4antigen makesuninfected T4 celllook like aninfected cellComplement-mediated lysis
  • 138. Why do all T4 cells disappear? Induction of apoptosis CD8 gp120 MacrophagHIVcell e (no CD4 antigen) chemokin e CXCR 4 G protein signal ? ? Binding to Binding to CXCR4 CXCR4 results results in in expression expression of of TNF-alpha TNF-alpha on
  • 139. Why do all T4 cellsdisappear? Induction of apoptosis CD8 cell CXCR 4 Macrophag Deat e h CD8 T cell
  • 140. Macrophages may be infected by two routesHIV gp120 CD4 HIV gp120 binds to macrophage CD4 antigen Virus is opsonized by anti gp120 antibodies which Fc receptor bind to macrophage Fc receptors - an Anti-gp120 vaccine problem enhancing antibody HIV
  • 141. Overview: Hepatitis Virology Transmission Epidemiology Pathogenesis Symptoms Diagnosis Management Prevention
  • 142. Viral Hepatitis - Overview Types of Hepatitis A B C D ESource of Feces Blood Blood Blood Feces Blood-derived Blood-derived Blood-derivedVirus body fluids body fluids body fluidsRoute of Fecal-Oral Percutaneous Percutaneous Percutaneous Fecal-Trans- Permucosal Permucosal Permucosal OralmissionChronic No Yes Yes Yes NoInfectionPrimary Pre/Post- Pre/Post- Blood Donor Pre/Post- Ensure safe Exposure Exposure Screening Exposure drinkingPrevent- Immunization water Immunization Immunizationion Risk Behavior Handwashing Risk Behavior Modification Risk Behavior Modification Modification
  • 143. Hepatitis A, B, and C at a GlanceVirus Sex IDU Trans- Fecal- Occu- Course of Infection Does Vaccine fusion Oral pational Protective Available Immunity Develop?A High Low* Low High None Acute -> Resolved Yes YesB High High Low None High Acute -> Chronic Yes Yes 90% of infants 30% in children aged 1-5 10% of older children and adults.C Low High Low None Low Acute -> Chronic No No in 75%-85% of adults.
  • 144. Age at Infection – Viral Hepatitis Perinatal Childhood Adolescent AdultHAV - ++++ ++ +++HBV ++ ++ +++ +++++HCV + - + +++++
  • 145. REPORTED CASES OF SELECTED NOTIFIABLE DISEASES PREVENTABLE BY VACCINATION, UNITED STATES, 2001 Hepatitis A 10,609 Hepatitis B 7,843 Pertussis 7,580 Meningococcal disease 2,333 H. influenzae, invasive 1,597 Mumps 266 Measles 116 Source: NNDSS, CDC
  • 146. HEPATITIS A VIRUS
  • 147. Hepatitis A Structure
  • 148. Hepatitis A Virus: Structure and Classification RNA Picornavirus • Separate genus because of differences with other enteroviruses • Naked icosahedral capsid • SS RNA (740 nucleotides) • Single serotype worldwide • Humans only reservoir
  • 149. HEPATITIS A VIRUS TRANSMISSION • Fecal-oral transmission • Close personal contact (e.g., household contact, sex contact, child day-care centers) • Contaminated food, water (e.g., infected food handlers, contaminated raw oysters) • Blood exposure (rare <<<1%) (e.g., injection drug use, rarely by transfusion)
  • 150. HEPATITIS A, UNITED STATES Most disease occurs in the context of community- wide outbreaks Infection transmitted from person to person in households and extended family settings - facilitated by asymptomatic infection among children Some groups at increased risk – specific factor varies – do not account for majority of cases – Children are the most frequently infected group No risk factor identified for 40%-50% of cases
  • 151. DISEASE BURDEN FROM HEPATITIS A UNITED STATES, 2001Number of acute clinical 10,609cases reportedEstimated number of acute 45,000clinical casesEstimated number of 93,000new infectionsPercent ever infected 31.3%
  • 152. GEOGRAPHIC DISTRIBUTION OFHEPATITIS A VIRUS INFECTION
  • 153. NUMBER OF YEARS REPORTED INCIDENCE OFHEPATITIS A EXCEEDED 10 CASES PER 100,000, BY COUNTY, 1987-1997 0-1 2-3 4-5 6-7 8-11
  • 154. Hepatitis A: Pathogenesis Incubation 4 weeks (range 2-6 weeks) Oral cavityGI tractliver via blood Replicates in hepatocytes (little damage to cells) released via bile to intestines 7-10 days prior to clinical symptoms Liver damage and clinical syndrome result of immune response and not direct effect of virus
  • 155. Hepatitis A: Clinical Features– An acute illness with:  discrete onset of symptoms (e.g. fatigue, abdominal pain, loss of appetite, intermittent nausea, vomiting)  jaundiceor elevated serum aminotransferase levels, dark urine, light stool  Adults usually more symptomatic  Patients are infective while they are shedding the virus in the stool- usually before the onset of symptoms  Mostcases resolve spontaneously in 2-4 weeks  Complete recovery 99%
  • 156. HEPATITIS A - CLINICAL FEATURES•Jaundice by <6 yrs <10% age group: 6-14 yrs40%-50% >14 yrs70%-80%•Rare complications: Fulminant hepatitis Cholestatichepatitis Relapsinghepatitis•Incubation period: Average 30 days Range 15-50 days
  • 157. EVENTS IN HEPATITIS A VIRUS INFECTION Clinical illness Infection ALT IgM IgGResponse Viremia HAV in stool 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Week
  • 158. Hepatitis A Diagnosis Detection of IgM antibody IgG positive 1-3 weeks later; suggests prior infection or vaccination.
  • 159. Hepatitis A Treatment Supportive- no specific role of antiviral therapy Lifelong immunity likely after infection or vaccination
  • 160. PREVENTING HEPATITIS A• Hygiene (e.g., hand washing)• Sanitation (e.g., clean water sources)• Hepatitis A vaccine (pre-exposure)• Immune globulin (pre- and post- exposure)
  • 161. HEPATITIS A VACCINES• Inactivated vaccine• Highly immunogenic •97%-100% of children, adolescents, and adults have protective levels of antibody within 1 month of receiving first dose; essentially 100% have protective levels after second dose• Highly efficacious •In published studies, 94%-100% of children protected against clinical hepatitis A after equivalent of one dose
  • 162. HEPATITIS A VACCINES1st dose at time 02nd dose 6-12 months afterwards
  • 163. POST-VACCINATION TESTINGNot recommended:  High response rate among vaccinees  Commercially available assay not sensitive enough to detect lower (protective) levels of vaccine-induced antibody
  • 164. DURATION OF PROTECTION AFTER HEPATITIS A VACCINATION Protection begins 4 weeks after vaccine Persistence of antibody • At least 5-8 years among adults and children Efficacy – No cases in vaccinated children at 5-6 years of follow-up Mathematical models of antibody decline suggest protective antibody levels persist for at least 20 years Other mechanisms, such as cellular memory, may contribute
  • 165. Hepatitis A Vaccine Recommendations Vaccine is recommended for the following persons 2 years of age and older: – Travelers to areas with increased rates of hepatitis A – Men who have sex with men – Injecting and non-injecting drug users – Persons with clotting-factor disorders (e.g. hemophilia) – Persons with chronic liver disease – Children living in areas with increased rates of hepatitis A during the baseline period from 1987- 1997- mainly West Coast.
  • 166. Hep A : Passive Immunization Hepatitis A immune globulin can be given up to 2 weeks after an exposure Immunity temporary (4-5 months) Also given in travelers leaving for endemic area on short notice (ie not enough time for the vaccine to be effective)
  • 167. Hepatitis A Surveillance & Response Urgently reportable condition in S.C. – Acute HAV infection must be reported by phone to DHEC within 24 hours. Investigation of a case of hepatitis A must be initiated by CO DADE and district epi staff within 24 hours of notification. All cases must be reported to CDC.
  • 168. Hepatitis B Virus
  • 169. Hepatitis B: Structure Member of the hepadnavirus group Virion also referred to as Dane particle 42nm enveloped virus Core antigens located in the center (nucleocapsid) – Core antigen (HbcAg) – e antigen (HBeAg)- an indicator of transmissibility (minor component of the core- antigenically distinct from HBcAg) 22nm spheres and filaments other forms- no DNA in these forms so they are not infectious (composed of surface antigen)- these forms outnumber the actual virions
  • 170. Structure and Replication Circular partially double stranded DNA of virus Initial replication to complete circular DNA with subsequent transcription to make several mRNAs some of which are translated into viral proteins One of the mRNAs is replicated with a reverse transcriptase making the DNA that will eventually be the core of the progeny virion Some DNA integrates into host genome causing carrier state Virus stable and resist many stresses making them more infectious
  • 171. Hepatitis B virus particles
  • 172. Epidemiology - United States1  100,000 new infections per year  8,000 - 32,000 chronic infections/year  5,000 - 6,000 deaths/year  1.25 million Americans with chronic HBV infection – 15 to 25% of chronically infected patients will die from chronic liver disease1. Center for Disease Control
  • 173. Geographic Distribution of Chronic HBV Infection HBsAg Prevalence 8% - High 2-7% - Intermediate <2% - Low
  • 174. High Prevalence of CHBV in AsianAmerican Communities is Often Overlooked1 US prevalence for chronic HBV is < 2% However, chronic HBV prevalence of 10- 15% in Asian American communities has been reported In Asian American men living in California, HCC ranks as a leading cause death – #2 in Vietnamese and Cambodian Americans – #4 in Chinese and Korean Americans 50% of children born to mothers with chronic HBV in the US are Asian American1. www.liver.stanford.edu
  • 175. Hepatitis B VirusModes of Transmission • Sexual • Parenteral • Perinatal
  • 176. Concentration of Hepatitis B Virus in Various Body Fluids Low/Not High Moderate Detectable blood semen urine serum vaginal fluid feceswound exudates saliva sweat tears breastmilk
  • 177. Risk Factors for Acute Hepatitis B United States, 1992-1993 Heterosexual* (41%) Injecting Drug Use Homosexual Activity (15%) (9%) Household Contact (2%) Health Care Employment (1%) Unknown (31%) Other (1%)* Includes sexual contact with acute cases, carriers, and multiple partners. Source: CDC Sentinel Counties Study of Viral Hepatitis
  • 178. HBV Pathogenesis Virus enters hepatocytes via blood Immune response (cytotoxic T cell) to viral antigens expressed on hepatocyte cell surface responsible for clinical syndrome 5 % become chronic carriers (HBsAg> 6 months) Higher rate of hepatocellular ca in chronic carriers, especially those who are “e” antigen positive Hepatitis B surface antibody likely confers lifelong immunity Hepatitis B e Ab indicates low
  • 179. Hepatitis B - Clinical Features• Incubation period: Average 60-90 days Range 45-180 days• Clinical illness (jaundice): <5 yrs, <10% 5 yrs, 30%-50% 1/3 adults-no symptoms• Acute case-fatality rate: 0.5%-1%• Chronic infection: <5 yrs, 30%-90% 5 yrs, 2%-10% • More likely in asymptomatic infections• Premature mortality from chronic liver disease: 15%-25%
  • 180. Hepatitis B Clinical Features Incubation Period: 6 weeks to 6 months (av. 120 days) Preicteric or Prodromal phase from initial symptoms to onset of jaundice usually lasts from 3 to 10 days: Non-specific, insidious onset of malaise, anorexia, n/v, RUQ pain, fever, headache, myalgias, skin rashes, arthralgias, arthritis, and dark urine beginning 1-2 days before onset of jaundice.
  • 181. Hepatitis B Clinical Features Icteric phase usually lasts from 1-3 weeks: jaundice, light or gray stools, hepatic tenderness, hepatomegaly. Convalescence phase may persist for weeks or months: Malaise, fatigue. Jaundice, anorexia, and other symptoms disappear.
  • 182. Hepatitis B Symptoms About 50%-60% of adults with HBV infection have no signs or symptoms. Those who do have symptoms might experience:  Jaundice  Fatigue  Abdominal pain  Loss of appetite  Nausea, vomiting  Joint pain
  • 183. Outcome of Hepatitis B Virus Infection 100 by Age at Infection 100 Symptomatic Infection (%) 80 80Chronic Infection 60 60 Chronic Infection 40 40(%) 20 20 Symptomatic Infection 0 0 Birth 1-6 months 7-12 months 1-4 years Older Children and Adults Age at Infection
  • 184. Possible Outcomes of HBV Infection Acute hepatitis B 95% of infection 3-5% of infant- Chronic HBV adult- acquiredinfection acquired infectionsChronic infections 12-25% in hepatitis 6-15% in 5 Cirrhosi years 5 20-23% in years Hepatocell s 5 years Liver ular failureDeath carcinoma Liver Death
  • 185. Acute Hepatitis B Virus Infection with Recovery Typical Serologic Course Symptoms HBeAg anti-HBe Total anti-HBcTiter HBsAg IgM anti-HBc anti-HBs 0 4 8 12 16 20 24 28 32 36 52 100 Weeks after Exposure
  • 186. Progression to Chronic Hepatitis B Virus Infection Typical Serologic Course Acute Chronic (6 months) (Years) HBeAg anti-HBe HBsAg Total anti- HBcTiter IgM anti- HBc 0 4 8 1 1 2 2 2 3 3 5 Years Weeks 6 0 4 8 2 6 2 after Exposure 2
  • 187. INTERPRETATION OF THE HEPATITIS B PANELTests Results InterpretationHBsAg Negative SusceptibleAnti-HBc NegativeAnti-HBs NegativeHBsAg Negative ImmuneAnti-HBc Negative or PositiveAnti-HBs PositiveHBsAg PositiveAnti-HBc Positive Acute InfectionIgM Anti-HBc PositiveAnti-HBs NegativeHBsAg Positive Chronic InfectionAnti-HBc PositiveIgM Anti-HBc NegativeAnti-HBs NegativeHBsAg Negative Four possible interpretationsAnti-HBc PositiveAnti-HBs Negative
  • 188. Interpretation HBsAg negative HBcAb positive HBsAb negative1. May be recovering from acute infection.2. May be distantly immune and test is not sensitive enough to detect very low level of HBsAb in serum.3. May be susceptible with a false positive HBcAb.4. May be undetectable level of HBsAg present in the serum and the person is actually a carrier.
  • 189. Current Treatment Options for HBV Pegylated Interferon alfa (Intron A) Lamivudine (Epivir HBV) Adefovir dipivoxil (Hepsera)
  • 190. Elimination of Hepatitis B Virus Transmission United States Strategy• Prevent perinatal HBV transmission• Routine vaccination of all infants• Vaccination of children in high-risk groups• Vaccination of adolescents – all unvaccinated children at 11-12 years of age – “high-risk” adolescents at all ages
  • 191. Hepatitis B Vaccine Infants: several options that depend on status of the mother – If mother HepBsAg negative: birth, 1-2m,6- 18m – If mother HepBsAg positive: vaccine and Hep B immune globulin within 12 hours of birth, 1-2m, <6m Adults – 0, 1, 6 months Vaccine recommended in – All those aged 0-18 – Those at high risk
  • 192. Hepatitis B High Risk Groups Persons with multiple sex partners or diagnosis of a sexually transmitted disease Men who have sex with men Sex contacts of infected persons Injection drug users Household contacts of chronically infected persons Infants born to infected mothers Infants/children of immigrants from areas with high rates of HBV infection Health care and public safety workers Hemodialysis patients
  • 193. Estimated Incidence of Acute Hepatitis B United States, 1978-1995 80 HBsAg screening Infant Vaccine of pregnant immunization 70 licensed women recommende recommended d 60 OSHA Rule 50 enactedPopulationCases per Adolescent100,000 40 immunization recommende d 30 20 * Decline among Decline 10 among homosexual men & injecting 0 HCWs drug users 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95* Provisional date Year
  • 194. Hepatitis B: Passive Immunization Infants of surface antigen positive mothers Exposures to infected blood or infected body fluids in individuals who are unvaccinated, unknown vaccination, or known non- responders. – Ideally within 24 hours – Probably not effective >7days post exposure
  • 195. Hepatitis B Surveillance Acute Hepatitis B is an urgently reportable condition. It must be reported by phone to DHEC within 24 hours. Chronic Hepatitis B is a reportable condition and must be reported to DHEC within 7 days. Perinatal Hepatitis B is a reportable condition and must be reported to
  • 196. Hepatitis B Surveillance Acute,chronic, and perinatal hepatitis B must be reported to CDC. CDC and S.C. conducts enhanced surveillance on acute and perinatal hepatitis B cases.
  • 197. Hepatitis D (Delta) Virusantigen HBsAg RNA
  • 198. Hepatitis D Structure Defective virus that requires co- infection with hepatitis B for replication Enveloped with SS RNA genome Onlyantigen encoded in the delta antigen
  • 199. Hepatitis D virus genome
  • 200. Hepatitis D Virus Modes of Transmission• Percutaneous exposures – injecting drug use• Permucosal exposures – sex contact
  • 201. Geographic Distribution of HDV Infection Taiwan Pacific IslandsHDV Prevalence High Intermediat e Low Very Low No Data
  • 202. Hepatitis D:Pathogenesis Pathogenesis – Immune mediated – Co-infection- infection with B at the same time (more severe) – Superinfection: acquisition of Hep D in chronically Hep B
  • 203. Sequelae of Hepatitis D virus
  • 204. Hepatitis D - Clinical Features• Coinfection –severe acute disease –low risk of chronic infection• Superinfection –usually develop chronic HDV infection –high risk of severe chronic liver disease
  • 205. HBV - HDV Coinfection Typical Serologic Course Symptoms ALT Elevated anti-Titer IgM anti- HBs HDV HDV RNA HBs Ag Total anti-HDV Time after Exposure
  • 206. HBV - HDV Superinfection Typical Serologic Course Jaundice Symptoms Total anti-HDV ALTTiter HDV RNA HBsAg IgM anti-HDV Time after Exposure
  • 207. Hepatitis C Virus
  • 208. Hepatitis D - Prevention• HBV-HDV Coinfection Pre or postexposure prophylaxis to prevent HBV infection• HBV-HDV Superinfection Education to reduce risk behaviors among persons with chronic HBV infection• Alpha interferon may help reduce hepatocellular damage
  • 209. Hepatitis C viruses particles and genome
  • 210. Hepatitis C Structure and Classification Member of the flavivirus family (other members yellow fever and dengue) Enveloped single stranded RNA virus Humans and chimpanzees only known reservoirs 6 serotypes (genotypes) and multiple subtypes based on high variability of envelope glycoproteins
  • 211. Hepatitis C Virus Infection, United States New infections per year 1985-89 242,000 2001 25,000 Deaths from acute liver failure Rare Persons ever infected (1.8%) 3.9 million (3.1-4.8)* Persons with chronic infection 2.7 million (2.4-3.0)* HCV-related chronic liver disease 40% - 60% Deaths from chronic disease/year 8,000-10,000 *95% Confidence Interval
  • 212. Estimated Incidence of Acute HCV Infection United States, 1960-2001 140New Infections/100,000 120 100 Decline in injection 80 drug users 60 40 Decline in transfusion recipients 20 0 1960 1965 1970 1975 1980 1985 1989 1992 1995 1998 2001 Year Source: Hepatology 2000;31:777-82; Hepatology 1997;26:62S-65S; CDC, unpublished data
  • 213. Exposures Known to Be Associated With HCV Infection in the United States Injecting drug use Transfusion, transplant from infected donor Occupational exposure to blood – Mostly needle sticks Iatrogenic (unsafe injections) Birth to HCV-infected mother Sex with infected partner – Multiple sex partners
  • 214. Sources of Infection for Persons With Hepatitis C Injecting drug use 60% Sexual 15% Transfusion 10% (before screening) Occupational 4% Other 1%* Unknown 10% * Nosocomial; iatrogenic; perinatalSource: Centers for Disease Control and Prevention
  • 215. Posttransfusion Hepatitis C 30 All volunteer donors HBsAg % of Recipients Infected 25 20 15 Donor Screening for HIV Risk Factors Anti-HIV 10 ALT/Anti-HBc Anti-HCV 5 Improved HCV Tests 0 1965 1970 1975 1980 1985 1990 1995 2000 YearAdapted from HJ Alter and Tobler and Busch, Clin Chem 1997
  • 216. Injecting Drug Use and HCV Transmission Highly efficient – Contamination of drug paraphernalia, not just needles and syringes Rapidly acquired after initiation – 30% prevalence after 3 years – >50% after 5 years Four times more common than HIV
  • 217. Occupational Transmission of HCV Inefficient by occupational exposures Average incidence 1.8% following needle stick from HCV-positive source – Associated with hollow-bore needles Case reports of transmission from blood splash to eye; one from exposure to non-intact skin Prevalence 1-2% among health care workers – Lower than adults in the general population – 10 times lower than for HBV infection
  • 218. Perinatal Transmission of HCV Transmission only from women HCV- RNA positive at delivery – Average rate of infection 6% – Higher (17%) if woman co-infected with HIV – Role of viral titer unclear No association with – Delivery method – Breastfeeding Infected infants do well – Severe hepatitis is rare
  • 219. Sexual Transmission of HCV Occurs, but efficiency is low – Rare between long-term steady partners – Factors that facilitate transmission between partners unknown (e.g., viral titer) Accounts for 15-20% of acute and chronic infections in the United States Partner studies – Low prevalence (1.5%) among long-term partners  infections might be due to common percutaneous exposures (e.g., drug use), BUT – Male to female transmission more efficient  more indicative of sexual transmission
  • 220. Household Transmission of HCV Rare but not absent Could occur through percutaneous/mucosal exposures to blood – Contaminated equipment used for home therapies  IV therapy, injections – Theoretically through sharing of contaminated personal articles (razors, toothbrushes)
  • 221. Other Potential Exposures to Blood No or insufficient data showing increased risk – intranasal cocaine use, tattooing, body piercing, acupuncture, military service No associations in acute case-control or population-based studies Cross-sectional studies in highly selected groups with inconsistent results – Temporal relationship between exposure and infection usually unknown – Biologically plausible, but association or causal relationship not established
  • 222. Hep C: Pathogenesis Blood-borne pathogen that infects hepatocytes Much like Hep A and B, liver damage and clinical illness due more to elicited immune response as opposed to direct cytopathic effect of the virus Likely cytotoxic T cells that mediate most of the damage Like other chronic liver diseases (Hep B and chronic alcoholism), can cause hepatocellular ca (HCC) Some genotypes more amenable to therapy- i.e. 3a
  • 223. Features of Hepatitis C Virus InfectionIncubation period Average 6-7 weeks Range 2-26 weeksAcute illness (jaundice) Mild (<20%)Case fatality rate LowChronic infection 60%-85%Chronic hepatitis 10%-70% (most asx) Age-Cirrhosis related <5%-20%Mortality from CLD 1%-5%
  • 224. Hepatitis C: Clinical Features Acuteinfection asymptomatic in over 80% of patients, when present, acute illness usually mild – Acute symptoms include jaundice, nausea, abdominal pain, loss of appetite, dark urine
  • 225. Hepatitis C: Extrahepatic Manifestations  Seen with chronic infection  ? Due to immune complexes  Extrahepatic manifestations – Essential mixed cryoglobulinemia (vasculitis, skin rash, fatigue) – Porphyria cutanea tarda – Membranoproliferative glomerulonephritis – ?Diabetes mellitus – Other autoimmune disease – ?Lymphoma
  • 226. Porphyria cutanea tarda
  • 227. Chronic Hepatitis C Factors Promoting Progression or Severity Increased alcohol intake Age > 40 years at time of infection HIV co-infection Other – Male gender – Chronic HBV co-infection
  • 228. Serologic Pattern of Acute HCV Infection with Recovery anti- Symptoms +/- HCV HCV RNATiter ALT Norm 0 1 2 3 al 5 6 1 2 3 4 4 Mont Year Time after Exposure hs s
  • 229. Serologic Pattern of Acute HCV Infection with Progression to Chronic Infection anti- Symptoms +/- HCV HCV RNA Titer ALT Norm 0 1 2 3 4 al 6 1 2 3 4 5 Mont Year Time after Exposure hs s
  • 230. Hepatitis C: Diagnosis ELISA-a serological test which is usually. positive within 2-5 months after infection – 3rd generation assays now 99% specific and sensitive Confirmatory testing – PCR (positive 1-2 weeks post infection) both quantitative and qualitative (I.e. ye/no) available – RIBA (recombinant immunoblot assay)- looks for 2 or more antibodies to HCV viral antigens Genotype testing done when treatment anticipated
  • 231. HCV Testing Routinely RecommendedBased on increased risk for infection Ever injected illegal drugs Received clotting factors made before 1987 Received blood/organs before July 1992 Ever on chronic hemodialysis Evidence of for exposure managementBased on need liver disease Healthcare, emergency, public safety workers after needle stick/mucosal exposures to HCV-positive blood Children born to HCV-positive women
  • 232. HCV Infection Testing Algorithm for Diagnosis of Asymptomatic Persons Screening Test for Negative STOP Anti-HCV Positive OR RIBA for Negative NAT for HCV Anti-HCV RNA Negative Indeterminate Positive Positive Additional Laboratory Medical STOP Evaluation (e.g. PCR, ALT) Evaluation Negative PCR, Positive PCR, Normal ALT Abnormal ALTSource: MMWR 1998;47 (No. RR 19)
  • 233. Medical Evaluation and Management for Chronic HCV Infection Assess for biochemical evidence of CLD Assess for severity of disease and possible treatment, according to current practice guidelines – 40-50% sustained response to antiviral combination therapy (peg interferon, ribavirin) – Vaccinate against hepatitis A Counsel to reduce further harm to liver – Limit or abstain from alcohol
  • 234. Hepatitis C Therapy Standard of care is pegylated interferon alpha and ribavirin Many barriers to treatment as the above regimen is difficult to take and has many systemic side effects (fatigue, myalgias, depression, anemia to name a few) Overall response rate to treatment
  • 235. Postexposure Management for HCV IG, antivirals not recommended for prophylaxis Follow-up after needlesticks, sharps, or mucosal exposures to HCV-positive blood – Test source for anti-HCV – Test worker if source anti-HCV positive  Anti-HCV and ALT at baseline and 4-6 months later  For earlier diagnosis, HCV RNA at 4-6 weeks – Confirm all anti-HCV results with RIBA Refer infected worker to specialist for medical evaluation and management
  • 236. Hepatitis E Virus
  • 237. Hepatitis E Non-enveloped single stranded RNA virus Resembles calicivirus or Norwalk agent Similarillness to Hep A except high mortality in pregnant women
  • 238. Geographic Distribution of Hepatitis EOutbreaks or Confirmed Infection in >25% of Sporadic Non-ABC Hepatitis
  • 239. Hepatitis E - Epidemiologic Features• Most outbreaks associated with fecally contaminated drinking water• Minimal person-to-person transmission• U.S. cases usually have history of travel to HEV-endemic areas
  • 240. Hepatitis E - Clinical Features• Incubation period: Average 40 days Range 15-60 days• Case-fatality rate: Overall, 1%-3% Pregnant women, 15%-25%• Illness severity: Increased with age• Chronic sequelae: None identified
  • 241. Hepatitis E Virus Infection Typical Serologic Course Symptoms ALT IgG anti- HEV IgM anti-Titer HEV Virus in stool 0 1 2 3 4 5 6 7 8 9 1 1 1 1 Weeks after Exposure 0 1 2 3
  • 242. Prevention and Control Measures for Travelers to HEV-Endemic Regions• Avoid drinking water (and beverages with ice) of unknown purity, uncooked shellfish, and uncooked fruit/vegetables not peeled or prepared by traveler• IG prepared from donors in Western countries does not prevent infection• Unknown efficacy of IG prepared from donors in endemic areas• Vaccine?
  • 243. INFLUENZA VIRUS
  • 244. „FLU‟ True influenza – influenza virus A or influenza virus B (or influenza virus C infections - much milder) Febrilerespiratory disease with systemic symptoms caused by a variety of other organisms often inaccurately called „flu‟
  • 245. South Carolina 1996-1997 DHEC bulletin malathia influenzae per le stel no virus CULTURE RESULTS influenza A influenza Bhttp://www.state.sc.us/dhec/LAB/labbu017.htm
  • 246. THE IMPACT OF INFLUENZA PANDEMICSDeaths: 1918-19 Spanish flu 500,000 US 20,000,000 world 1957-58 Asian flu 70,000 US
  • 247. THE IMPACT OF INFLUENZA  In the United States, on average:  36,000 deaths per year  114,000 hospitalizations per yearCDC: MMWR 53:8-11, 2004
  • 248. THE IMPACT OF INFLUENZA recently some increase in morbidity and mortality - possible factors? – more elderly people – CF patients live longer – more high risk neonates – more immunosuppressed patients
  • 249. ORTHOMYXOVIRUSESpleomorphicinfluenza types A,B,Cfebrile, respiratory illness with systemic symptoms http://www.uct.ac.za/depts/mmi/stannard/fluvirus.ht
  • 250. ORTHOMYXOVIRUSES HA - hemagglutinin NA - neuraminidase helical nucleocapsid (RNA plu NP protein) lipid bilayer membrane polymerase complex M1 proteintype A, B, C : NP, M1 proteinsub-types: HA or NA protein
  • 251. TRANSMISSION AEROSOL – 100,000 TO 1,000,000 VIRIONS PER DROPLET 18-72 HR INCUBATION SHEDDING
  • 252. NORMAL TRACHEAL MUCOSA 3 DAYS POST-INFECTION 7 DAYS POST-INFECTIONLycke and Norrby Textbook of Medical Virology 1983
  • 253.  DECREASED CLEARANCE RISK BACTERIAL INFECTION VIREMIA RARE Lycke and Norrby Textbook of Medical Virology 1983
  • 254. RECOVERY INTERFERON - SIDE EFFECTS INCLUDE: – FEVER, MYALGIA, FATIGUE, MALAISE CELL-MEDIATED IMMUNE RESPONSE TISSUE REPAIR – CAN TAKE SOME TIME
  • 255. An immunological diversion INTERFERON
  • 256. INTERFERONtimecourse of virus production will vary fro
  • 257. INTERFERON
  • 258. INTERFERON antiviral stateantiviral state antiviral state antiviral state
  • 259. INTERFERON antiviral stateantiviral state antiviral state antiviral state
  • 260. INTERFERON antiviral stateantiviral state antiviral state antiviral state
  • 261. INTERFERONTHE VIRUSES ARE COMIN PAUL REVERE http://www.mfa.org/collections/one_hour/6.htm http://www.paulreverehouse.org/midnight.html
  • 262. TYPES OF INTERFERONTYPE I Interferon-alpha (leukocyte interferon, about 20 related proteins) - leukocytes, etc Interferon-beta (fibroblast interferon) - fibroblasts, epithelial cells, etc
  • 263. INDUCTION OF INTERFERONinterferon-alpha and interferon-beta - viral infection (especially RNA viruses), double stranded RNA, certain bacterial components - strong anti-viral propertiesinterferon-gamma - antigens, mitogenic stimulation lymphocytes
  • 264. INTERFERON induces variety of proteins in target cells manyconsequences, not all fully understood
  • 265. INTERFERON-ALPHA AND INTERFERON-BETA
  • 266. interferon-alpha, interferon-beta interferon receptor induction of induction of induction of2’5’oligo A synthase ribonuclease L protein kinase R (PKR) ds RNA 2’5’oligo A ds RNA activated activated activated2’5’oligo A synthase ribonuclease L protein kinase R ATP ATP phosphorylated 2’5’oligo A initiation factor (eIF- 2) mRNA degraded inhibition of protein synthesi
  • 267. interferons only made when needed
  • 268. OTHER EFFECTS OF INTERFERONS ALL TYPES – INCREASE MHC I EXPRESSION  CYTOTOXIC T-CELLS – ACTIVATE NK CELLS  CAN KILL VIRALLY INFECTED CELLS
  • 269. OTHER EFFECTS OF INTERFERONS INTERFERON-GAMMA – INCREASES MHC II EXPRESSION ON APC  HELPER T-CELLS – INCREASES ANTIVIRAL POTENTIAL OF MACROPHAGES  INTRINSIC  EXTRINSIC
  • 270. THERAPEUTIC USES OF INTERFERONS ANTI-VIRAL – e.g. interferon-alpha is currently approved for certain cases of acute and chronic HCV and chronic HBV MACROPHAGE ACTIVATION – interferon-gamma has been tried for e.g. lepromatous leprosy, leishmaniasis, toxoplasmosis ANTI-TUMOR – have been used in e.g. melanoma, Kaposi‟s sarcoma, CML MULTIPLE SCLEROSIS
  • 271. Viral response to host immune systemViruses may : block interferon binding inhibit function of interferon-induced proteins inhibit NK function interfere with MHC I or MHC II expression block complement activation inhibit apoptosis etc!
  • 272. SIDE EFFECTS OF INTERFERONS FEVER MALAISE FATIGUE MUSCLE PAINS
  • 273. BACK TO INFLUENZA
  • 274. PROTECTION AGAINST RE-INFECTION IgG and IgA – IgG less efficient but lasts longer antibodies to both HA and NA important – antibody to HA more important (can neutralize)
  • 275. SYMPTOMS FEVER HEADACHE MYALGIA COUGH RHINITIS OCULAR SYMPTOMS
  • 276. CLINICAL FINDINGS SEVERITY – VERY YOUNG – ELDERLY – IMMUNO- COMPROMISED – HEART OR LUNG DISEASE
  • 277. PULMONARY COMPLICATIONS CROUP (YOUNG CHILDREN) PRIMARY INFLUENZA VIRUS PNEUMONIA SECONDARY BACTERIAL INFECTION – Streptococcus pneumoniae – Staphlyococcus aureus – Hemophilus influenzae
  • 278. NON-PULMONARY COMPLICATIONS myositis (rare, > in children, > with type B) cardiac complications recent studies report encephalopathy – 2002/2003 season studies of patients younger than 21 yrs in Michigan - 8 cases (2 deaths) liver and CNS – Reye‟s syndrome peripheral nervous system – Guillian-Barré syndrome
  • 279. Reye‟s syndrome liver - fatty deposits brain - edema vomiting, lethargy, coma risk factors – youth – certain viral infections (influenza, chicken pox) – aspirin
  • 280. Guillian-Barré syndrome 1976/77 swine flu vaccine – 35,000,000 doses  354 cases of GBS  28 GBS-associated deaths  recent vaccines much lower risk
  • 281. MORTALITY MAJORCAUSES OF INFLUENZA VIRUS- ASSOCIATED DEATH – BACTERIAL PNEUMONIA – CARDIAC FAILURE 90%OF DEATHS IN THOSE OVER 65 YEARS OF AGE
  • 282. DIAGNOSIS ISOLATION – NOSE, THROAT SWAB – TISSUE CULTURE OR EGGS SEROLOGY PCR RAPID TESTS provisional - clinical picture + outbreak
  • 283. ANTIGENIC DRIFT HA and NA accumulate mutations – RNA virus immune response no longer protects fully sporadic outbreaks, limited epidemics
  • 284. ANTIGENIC SHIFT “new” HA or NA proteins pre-existing antibodies do not protect may get pandemics
  • 285. INFLUENZA A PANDEMICSRyan et al., in Sherris MedicalMicrobiology
  • 286. where do “new” HA and NA come from?13 types HA 9 types NA – all circulate in birds pigs – avian and human
  • 287. Where do “new” HA and NA come from?
  • 288. Where do “new” HA and NA come from- can „new‟ bird flu directly infect humans? Bird flu H5N1?
  • 289. why do we not have influenza B pandemics? so far no shifts have been recorded no animal reservoir known
  • 290. SURVEILLANCECDC/Katherine Lord
  • 291. actual percentage of deaths(CDC MMWR July 1, 2005 / 54(25);631-634)
  • 292. % typed cases100 90 80 70 60 H1N1 50 H3N2 40 B 30 20 10 0 00/01 01/02 02/03 03/04 04/05 influenza
  • 293. VACCINE „BEST GUESS‟ OF MAIN ANTIGENIC TYPES – CURRENTLY  type A - H1N1  type A - H3N2  type B  each year choose which variant of each subtype is the best to use for optimal protection
  • 294. VACCINE inactivated egg grown some formulations licensed for children reassortant live vaccine approved 2003 – for healthy persons (those not at risk for complications from influenza infection) ages 5-49 years
  • 295. CDC
  • 296. OTHER TREATMENT REST, LIQUIDS, ANTI-FEBRILE AGENTS (NO ASPIRIN FOR AGES 6MTHS-18YRS) BEAWARE OF COMPLICATIONS AND TREAT APPROPRIATELY
  • 297. VIRAL AGENTS CAUSINGGASTROENTERITIS
  • 298. VIRAL AGENTS CAUSING GASTROENTERITIS1. Rotavirus2. Enteric adenoviruses3. Calicivirus4. Astrovirus
  • 299. ROTAVIRUSFamily ReoviridaeGenus Rotavirus
  • 300. ROTAVIRUS First isolated in 1973 from children with diarrhea EM identification from duodenal biopsies Human and animal strains
  • 301. ROTAVIRUS STRUCTURE
  • 302. ROTAVIRUS - STRUCTURE
  • 303. STRUCTURAL FEATURES OF ROTAVIRUS 60-80nm in size Non-enveloped virus EM appearance of a wheel with radiating spokes Icosahedral symmetry Double capsid Double stranded (ds) RNA in 11 segments
  • 304. STRUCTURE Double capsid (outer and innercapsid) Core with genome Capsid is cleaved by trypsin toform ISVP- infective sub-viral particle
  • 305. ROTAVIRUS- 3D STRUCTURE
  • 306. ROTAVIRUS- ultrastructure
  • 307. ROTAVIRUSEM STRUCTURE
  • 308. VIRAL STRUCTURAL PROTEINS (VP)  Outer structural proteins - VP7 and VP4 VP7 - Glycoprotein VP4 - protease-cleaved, P protein, viral hemagglutinin; forms spikes from the surface  Inner core structural proteins VP 1, 2, 3, 6  VP6 is an important antigenic
  • 309. STRUCTURE
  • 310. CLASSIFICATION Groups- 7 Groups (A through G) based on VP6 differences Group A is the most common and has 2subgroups
  • 311. CLASSIFICATION (contd.) Serotypes based on viral capsid proteins 14 G serotypes based on G protein (VP 7) differences 20 P serotypes based on P protein (VP4) Common PG combinations are:- P8G1, P8G2, P4G2, P8G4
  • 312. CLASSIFICATION (contd.) Electropherotypes are based on the mobility of RNA segments by PAGE Useful in epidemiologic studies
  • 313. ROTAVIRUS- PROPERTIES Virus is stable in the environment Relatively resistant to handwashing agents Susceptible to disinfection with 95% ethanol, „Lysol‟, formalin
  • 314. PATHOGENESIS Targeted host cells - mature enterocytes lining the tips of intestinal villi Intermediate/infective sub-viral particle (ISVP) produced through proteolysis Enter host cell by endocytosis Virus replicates in the host cell cytoplasm
  • 315. REPLICATION mRNA transcription with viral RNA polymerase Capsid proteins formed mRNA segments formed, assembled into immature capsid mRNA replicated to form double stranded RNA genome
  • 316. HISTOPATHOLOGY Mature enterocytes lining the tips of intestinal villi are affected Villous atrophy and blunting Death of the mature enterocytes
  • 317. HISTOPATHOLOGY Infiltration of lamina propria with mononuclear cells Repopulation of the villous tips with immature secretory cells [crypt hyperplasia]
  • 318. HISTOPATHOLOGY
  • 319. EPIDEMIOLOGYA major cause of diarrhea- associated hospitalizations and deaths Seroprevalence studies show that antibody is present in most by age 3y.
  • 320. ROTAVIRAL DISEASE BURDEN- World
  • 321. WORLDWIDE DISTRIBUTION OF ROTAVIRUS (Source- Centers for Disease Control and Prevention)
  • 322. EPIDEMIOLOGY - USA 2.7- 3.5 million affected each year Physician visits ~ 500,000/year 50,000-70,000 hospitalizations/year 20-40 deaths/year Cases with dehydration ~ 1-2.5% Economic impact
  • 323. EPIDEMIOLOGY Age- 4mo - 2 years Protection of younger infants through through transplacental antibody transfer Asymptomatic infections are common, especially in adults Nosocomial infections Outbreaks Severe Disease young, immunocompromised
  • 324. Epidemiology (contd.) Seasonality Winter months (Nov. through May in US) Gradual spread W to E Year-round in the tropics Incubation period - thought to be <4 days
  • 325. EPIDEMIOLOGY(Source- Centers for Disease Control and Prevention)
  • 326. SEASONAL SPREAD - U.S. (Source- CDC)
  • 327. TRANSMISSION Mainly person to person via fecal-oral route Fomites Foodand water-borne spread is possible Spreadvia respiratory route is speculated
  • 328. EPIDEMIOLOGY - spread Contagious from before onset of diarrhea to a few days after end of diarrhea Large amounts of viral particles are shed in diarrheal stools Infective dose is only 10-100 pfu
  • 329. EPIDEMIOLOGY Differences in Groups Group A infections are most common Group B has been associated with outbreaks in adults in China Group C is responsible for sporadic cases of diarrhea in infants around the world
  • 330. CLINICAL CASE A 22 month old female is admitted to the pediatric ward for cough and fever up to 103 F. Chest X ray shows left lower lobe pneumonia. She is being treated with intravenous Ceftriaxone and her fever is gradually improving. On hospital day #5, she develops diarrhea with 4 watery stools and a fever of 102 F. Stool studies showed no traces of blood and no fecal leukocytes. Further studies are pending.
  • 331. CLINICAL FEATURES Incubation period - thought to be <4 days Fever- can be high grade (>102 F in 30%) Vomiting, nausea precede diarrhea Diarrhea • usually watery (no blood or leukocytes) • lasts 3-9 days • longer in malnourished and immune deficient individuals. • NEC and hemorrhagic GE seen in neonates
  • 332. MECHANISM OF DIARRHEA Watery diarrhea due to net secretion of intestinal fluid Activation of the enteric nervous system Role of NSP4 peptide regions as an enterotoxin
  • 333. CLINICAL FEATURES (contd.) Dehydration is the main contributor to mortality. Secondary malabsorption of lactose and fat, and chronic diarrhea are possible
  • 334. DIAGNOSIS Antigen detection in stool by ELISA, LA (for Group A rotavirus) EM- non-Group A viruses also Culture- Group A rotaviruses can be cultured in monkey kidney cells Serology for epidemiologic studies
  • 335. TREATMENT AND PREVENTION Treatment Supportive- oral, IV rehydration Prevention Handwashing and disinfection of surfaces
  • 336. VACCINE Live tetravalent rhesus-human reassortant vaccine (Rotashield) Licensed for use in August 1998 Removed from the market in October 1999 due to risk of intussusception Cases were seen 3-20 days after vaccination Approx. 15 cases/1.5 million doses
  • 337. NEWER VACCINES Rotarix Rota Teq Monovalent G1P8 oral  Pentavalent Human- vaccine bovine reassortant vaccine Efficacy for prevention  Efficacy for prevention of severe disease = of severe disease = 85% 100%
  • 338. GASTROENTERITIS DUETO ENTERIC ADENOVIRUS
  • 339. GASTROENTERITIS DUE TO ADENOVIRUS  Types 40, 41  Belong to serogroup F
  • 340. Diarrhea due toEnteric Adenovirus Age <4 years Year round Spread via fecal-oral route
  • 341. CLINICAL FEATURES- Adenovirus gastroenteritis Incubation period 3 -10 days Diarrhea lasts for 10 -14 days Can also cause intussusception, mesenteric adenitis, appendicitis
  • 342. DIAGNOSIS Enteric adenoviruses Isolation requires special media- Graham 293 ELISA for rapid detection is available
  • 343. HUMANCALICIVIRUSES
  • 344. HUMAN CALICIVIRUSES (HuCV)• Family Caliciviridae• Non-enveloped RNA viruses with ss RNA• 27-35 nm in size• Contain a single capsid protein
  • 345. HUMAN CALICIVIRUSES Genomic analysis divides it into 4groupsHuman caliciviruses belong to 2genera
  • 346. CLASSIFICATION OF HuCVNLV (Norovirus) SLV (Sapovirus)Norwalk virus Sapporo virusHawaii virus Manchester virusSnow Mountain virus Houston/86Montgomery county London/92virusTaunton (England)
  • 347. MORPHOLOGY- typical• 32 cup-like depressions• EM appearance of “Star ofDavid”• 31-35 nm size• E.g.- Sapporo-like viruses
  • 348. HUMAN CALICIVIRUSES - SLV
  • 349. Morphology of HuCV- atypical• Smaller size- approx. 27 nm• Rough, feathery surface butno internal pattern• Small Round Structuredviruses• E.g.- Norwalk-like viruses
  • 350. SRSV- NORWALK VIRUS
  • 351. CLINICAL FEATURES Usual incubation Period is <24 hours (ranges from 12hrs. to 4 days) Short duration of illness <3 days Nausea, vomiting, fever, headache Abdominal cramping Watery diarrhea
  • 352. EPIDEMIOLOGY - Noroviruses Worldwide distribution >23 million cases/year in the U.S. Major cause of foodborne outbreaks of GE (>50%) Most people have had infections by age 4 years (by seroprevalence studies)
  • 353. SPREAD Person-to-person Fecal-oral spread (stool/vomitus) Fecal contamination of food or water Spread through fomites (stool/vomitus)
  • 354. SPREAD- Viability of Caliciviruses Survive in water chlorinated at routine levels (up to 10 ppm) Survive freezing, heating up to 60 C Evidently survive in steamed shellfish
  • 355. EPIDEMIOLOGY• Asymptomatic infections-seroconversion but asymptomatic shedding of virus• Low infective dose (~10 pfu)• Viral excretion during convalesence (~2 wk.)
  • 356. EPIDEMIOLOGY : Outbreaks Cruise ships, schools, nursing homes, Can involve infants and school-age children Source usually is contaminated food and water (E.g. seafood-oyster and shellfish, salads, cake icing, raw fruit etc.) Rapid secondary spread
  • 357. DIAGNOSIS Specimen- stool, vomitus, environmental swabs (during outbreak investigations) RT-PCR in state public health labs. Serology for epidemiologic purposes Immune EM is less used
  • 358. HUMANASTROVIRUS
  • 359. ASTROVIRUS Described in relation to an outbreak of gastroenteritis in 1975 Detected by EM Immunologically distinct from Human Caliciviruses Belong to family Astroviridae 8 human serotypes are known
  • 360. ASTROVIRUS- structure Small ss RNA virus Non-enveloped 27-32nm in size Round with an unbroken, smooth surface EM appearance of a 5 or 6 pointed star within smooth edge Contain 3 structural proteins
  • 361. ASTROVIRUS- EM STRUCTURE
  • 362. ASTROVIRUS - Epidemiology Worldwide Mainly in children <7 years of age. Transmission person-to-person via fecal-oral route Outbreaks due to fecal contamination of sea-food or water
  • 363. ASTROVIRUS - Clinical Features Infants and children are most often affected Short incubation period 1-4 days Nausea, vomiting, abdominal cramping and watery diarrhea Constitutional symptoms-fever, malaise, headache
  • 364. ASTROVIRUS - Diagnosis EM (virus shed in stool in great numbers) EIA RT-PCR
  • 365. Respiratory Syncytial Virus (RSV)
  • 366. Respiratory Syncytial Virus (RSV) Discovered in 1956Morris, Blount and Savage described a Chimpanzee Coryza Virus Accidental human infection lead torecognition of role in human infections
  • 367. RSV- syncytium formation
  • 368. Respiratory Syncytial Virus Family Paramyxoviridae Genus Pneumovirus Subgroups A and B
  • 369. RSV- Structure 100-350nm enveloped virus Spherical or pleomorphic shape Single stranded negative sense RNA 2 non-structural and 8 structural proteins
  • 370. RSV- Structure
  • 371. RSV- Structure
  • 372. RSV- Structure (contd.) Envelope Glycoproteins:- F and GG protein lacks H/N activity Subgroups „A‟ and „B‟ based on variations in G protein
  • 373. Pathogenesis•Entry through mucosa of noseand eye•Cell to cell spread withinrespiratory tract
  • 374. Pathogenesis (contd.)• Attachment via G protein to respiratory epithelium• Fusion with cell membrane - F protein• Syncytium formation (tissue culture) with multinucleated giant cells
  • 375. Pathogenesis
  • 376. RSV- syncytium formation
  • 377. RSV- syncytium formation
  • 378. Pathology•Mucosal edema•Increased mucin secretion•Cell necrosis within mucosa sloughing•Obstruction of lumina-debris, mucin•Peribronchial lymphocytic infiltration
  • 379. Immunity-role in pathogenesis Host immune response contributes to pathology (T cells, cytokines) IgE response in some people is linked to airway hyper-reactivity Cell-mediated immunity limits infection
  • 380. Epidemiology Important cause of lower respiratory disease in young infants (bronchiolitis and pneumonia) Worldwide distribution Most children infected at least once by age 4 years
  • 381. Epidemiology 75,000-125,000 infants are hospitalized each year in U.S. Account for 50-90% of hospitalizations for bronchiolitis Seasonal- fall through spring
  • 382. Epidemiology- seasonality (Source- CDC, NCIDOD)
  • 383. Epidemiology- seasonality (Source- CDC, NCIDOD)
  • 384. Regional variations in seasonality (Source- CDC, NCIDOD)
  • 385. Epidemiology - transmission Incubation Period- 2-8 days Virus survives on surfaces for up to 6 h. Transmission via droplets, fingers, fomites Nosocomial spread is common
  • 386. Epidemiology (contd.)• Asymptomatic viral shedding• Viral shedding lasts for <1 to 3weeks• Infants show high titer nasalshedding, especially initially (107/mL)
  • 387. Clinical Features Upper Respiratory Lower Respiratory Infection Infection (Bronchiolitis, Pneumonia) Fever  Cough Rhinitis  Poor feeding, Pharyngitis lethargy  Hypoxemia  Respiratory Distress (tachypnea, retractions)
  • 388. RSV Bronchiolitis- clinical features
  • 389. Radiologic features of RSV bronchiolitis Atelectasis -patchy/lobar Hyperinflation Streaking Perihilar infiltrates
  • 390. Radiologic features of RSV bronchiolitis
  • 391. RSV- Severe Disease Preterm Infants Chronic Lung Disease, BPD Cyanotic congenital heart disease Congestive heart failure Immunocompromised patients Neurologic or metabolic diseaes
  • 392. Diagnosis - specimens Nasal and tracheo-bronchial secretions Swabs, or aspirates Transport in viral culture medium and on ice Process immediately
  • 393. Diagnosis- methods Viral isolation PRMK, LLLC-MK-2 CPE in 2-5 days Shell vial technique with immunofluoresence Antigen detection EIA (Binax NOW/Quick lab RSV) RIA, IF Antibody detection- not useful clinically
  • 394. Diagnosis- RSV in Hep-2 cell culture (immunofluoresent stain)
  • 395. Treatment Supportive Fluids, oxygen, respiratory support, bronchodilators Antiviral Agents Ribavirin (Virazole), a syntheticguanosine analogue, given as an aerosol
  • 396. Preventing Spread Handwashing Disinfection of surfaces Gloves, masks, goggles, gowns Isolation, and cohort nursing Immunization
  • 397. Prevention of Disease• Active Immunization Formalin inactivated vaccine resulted in enhanced disease Subunit vaccines being studied
  • 398. Prevention of Disease(contd.)• Passive immunization (immunoprophylaxis) Pooled hyperimmune globulin (RespiGam) Monoclonal antibody to F protein- Palivizumab (Synagis)
  • 399. SYNAGIS for immunoprophylaxis against RSV infection• Monthly, IM, from Oct.-May• Children at high risk for severe disease due to RSV are candidates• High cost• Reduction in hospitalization
  • 400. HUMANMETAPNEUMOVIRUS A newly recognized pathogen
  • 401. Subfamily PneumovirinaeGenus Genus Pneumovirus Metapneumovirus Human RSV  Human Metapneumovirus (hMPV)
  • 402. hMPV PARTICLESinfected tMK−cell culture supernatants: negative contrast EM with PTA staining
  • 403. Human Metapneumovirus Member of Subfamily Pneumovirinae, genus Metapneumoirus 2 different genetic lineages “Discovered” in 2001 in the Netherlands Several reports of association with respiratory illness in children Co-infection with RSV PCR technique used in research labs
  • 404. Slow viral or priondiseases of the central nervous system
  • 405. Slow viral diseases of the central nervous system tempo of clinical disease protracted incubation period protracted course of disease multiple neurological symptoms
  • 406. SLOW INFECTIONS IN HUMANS TYPICAL AGENTS – SV40-like viruses (PML) – measles virus (SSPE) – rubella virus (PRP) ATYPICAL AGENTS – Kuru, – Creutzfeld-Jakob disease (CJD) – new variant CJD disease (nvCJD, vCJD)
  • 407. Progressive multifocal leukoencephalopathy Polyoma virus family, SV40-like (JC virus etc) progressive, usually fatal – HAART may help in AIDS patients noninflammatory demyelination (oligodendrocytes)
  • 408. SYMPTOMS weakness speech problems cognitive problems headaches gait problems visual problems sensory loss seizures http://medstat.med.utah.edu/WebPath/TUTORIAL/AIDS/AIDS.htm
  • 409. Progressive multifocal leukoencephalopathy reactivationof latent infection 70-80% population are seropositive associated with immunosuppression – 1979:1.5 per 10,000,000 population – 2004: 1 in 20 AIDS patients
  • 410. MEASLES VIRUS paramyxovirus family (morbillivirus genus) sub-acute sclerosing panencephalitis – inflammatory disease – defective virus – ~1-10 yrs after initial infection early infection with measles is a risk factor rare complication of measles (7 in 1,000,000 patients) vaccine protects against SSPE
  • 411. RUBELLA VIRUS• togavirus family (rubrivirus genus)• progressive rubella panencephalitis – inflammatory disease – years after initial infection• congenital / very early infections• very very rare
  • 412. spongiformencephalopathiestransmissible cerebral amyloidoses prion diseases
  • 413. TRANSMISSIBLE SPONGIFORMENCEPHALOPATHIES (TSEs, TRANSMISSIBLECEREBRAL AMYLOIDOSES, PRION DISEASES)• human – Kuru – Creutzfeldt-Jakob disease (CJD) – Gerstmann-Straussler-Scheinker syndrome (GSS) – fatal familial insomnia (FFI) – variant CJD („human BSE‟)• animal – scrapie (sheep and goats) – bovine spongiform encephalopathy (BSE) – transmissible mink encephalopathy
  • 414. ATYPICAL AGENTS atypical viruses atypical agents prions
  • 415. ATYPICAL AGENTS SIMILAR TO  DIFFERENT FROM VIRUSES VIRUSES – small – no detectable – filterable virions in infected – need host cells tissues – no machinery for – no detectable energy generation virions in purified or protein synthesis infectious material – if nucleic acid is present, very small – very resistant
  • 416.  RESISTANT TO OR ONLY PARTIALLY INACTIVATED BY: – formaldehyde – ethanol – glutaraldehyde – ultraviolet and ionizing irradiation – non-ionic detergents INACTIVATED BY: – autoclaving (121C for one hour) (> standard) – 5% sodium hypochlorite – sodium hydroxide – proteases, urea, other protein denaturants
  • 417. purified infectious material protein present (PrP) proteases inactivate nucleic acid controversial
  • 418.  CNS PRION DISEASE LONG INCUBATION SLOW COURSE OF DISEASE (FATAL) SPONGIFORM ENCEPHALOPATHY VACUOLATION OF NEURONS FIBRILLAR AGGREGATES, AMYLOID-TYPE MATERIAL (form plaques) RARE IN MAN
  • 419. SCRAPIE sheep loss of muscular control wasting glial proliferation vacuolation of neurons amyloid plaques abnormal properties infectious material
  • 420. KURU human disease tremors, ataxia, weakness dementia, death amyloid plaques spongiform changes transmission – contact with infectious material
  • 421. CREUTZFELDT-JAKOB DISEASE appearance of brain at autopsy dementia, myoclonus, ataxia 16-80+, usually 50-70 10% familial sporadic form acquired form (eg. iatrogenic CJD) will discuss variant CJD (vCJD or nvCJD) separately
  • 422. CREUTZFELDT-JAKOB DISEASE classical form noevidence for direct person to person transmission – blood – milk – other body fluids – intimate social contact
  • 423. CREUTZFELDT-JAKOB DISEASE iatrogenic CJD – human cadaver growth hormone – human cadaver gonadotropin – dural mater grafts – corneal transplantation – neurosurgical instruments – stereotactic EEG electrodes
  • 424. variant CJD nvCJD, vCJD younger at presentation, more protracted course of disease often patients present with psychiatric symptoms BSE connection distinctive pathological appearance distinctive properties of the PrPres agent is in some peripheral tissues – lymphoid tissues – 2 probable cases where transmitted by blood
  • 425. Cases of vCJD in UK, Oct 4th 2005 definite/probable vCJD cases still alive in UK: 6 http://www.cjd.ed.ac.uk/figures.htm
  • 426. Amino acid 129 Met or Val? - both variants found in the human population Britain – 100% of clinical vCJD cases are MM  AreMV, VV immune to vCJD, or will they develop vCJD later on? – 83% of sporadic CJD cases are MM – however, only 37% of the UK population is MM Britain, France, Japan – excess of VV in growth hormone recipients with iatrogenic CJD does heterozygosity (M/V) offer some
  • 427. OTHER HUMAN PRION DISEASES Gerstmann-Sträussler-Scheinker syndrome (GSS) (familial) – motor – sometimes regarded as subclass of CJD fatal familial insomnia (FFI) – circadian rhythm problems – hypothalamus
  • 428. IMMUNE RESPONSE no inflammatory response no interferon induction no antibody response no cell-mediated response
  • 429. TREATMENT invariably fatal attemptsat drug therapy disappointing blood brain barrier
  • 430. DIAGNOSIS CLINICALPICTURE, EEG USUALLY CONFIRMED POST- MORTEM NOW HAVE ANTIBODIES RAISED IN RECOMBINANT MICE – can use on biopsy of brain (or peripheral lymphoid tissue in vCJD)
  • 431. PLAQUES PrP NOT THE SAME AS IN ALZHEIMERS
  • 432. VIRAL ZOONOSES ZOONOTIC VIRUSES – TRANSMISSIBLE FROM ANIMALS  ARTHROPODS – often via a blood sucking arthropod  VERTEBRATES – bites, body fluids, inhalation etc
  • 433. VIRAL ZOONOSES ARTHROPOD BORNE
  • 434. transmission arthropod vectors (blood sucking) Manyarboviral diseases world wide (hundreds)
  • 435.  ARBOVIRUSES – ENCEPHALITIS – FEBRILE DISEASES – HEMORRHAGIC FEVERS
  • 436. BirdsMammals
  • 437. ARTHROPOD Habitat VERTEBRATE  Migratory activity Diurnal activity  Persistence of Preferred host viremia Annual activity  Clinical Overwintering consequences ability  Reservoir ? Transovarial  Dead end host? transmission
  • 438. PREVENTION SURVEILLANCE VECTOR CONTROL REPELLENTS CLOTHING TIMING OF ACTIVITY (OR CANCELLATION) VACCINE
  • 439. SYLVATIC (JUNGLE) CYCLE vertebrate arthropod arthropod vertebrate man
  • 440. URBAN CYCLE manarthropod arthropod man
  • 441. OUTBREAKS TEND TO BE SUMMER/EARLY FALL SPORADIC UNPREDICTABLE
  • 442. ARBOVIRAL DISEASE MANY DIFFERENT ARBOVIRUSES CAUSE DISEASE OFTEN SUB-CLINICAL INITIAL VIRAL REPLICATION – ENDOTHELIAL CELLS – MACROPHAGES/MONOCYTE LINEAGE INTERFERON (RNA VIRUSES) VIREMIA
  • 443. RECOVERY INTERFERON CELL-MEDIATED IMMUNITY ANTIBODYMAY PLAY A ROLE DURING VIREMIC PHASE
  • 444. DIAGNOSIS SPECIALIZED LABS (Commercial labs now testing for West Nile Virus) – Immunological techniques – PCR
  • 445. RESISTANCE IgG
  • 446. ARBOVIRUSES – ENCEPHALITISFAMILY DISTRIBUTIONTOGAVIRIDAEEastern equine encephalitis East US, CanadaWestern equine encephalitis West US, Canada, Mexico, BrazilVenezuelan equine encephalitis Central and S America, Texas, FloridaFLAVIVIRIDAEWest Nile virus encephalitis North America, parts of Europe, parts of AfricaSt Louis encephalitis North AmericaBUNYAVIRIDAECalifornia serogroup (La Crosse etc) North America
  • 447. ARBOVIRUS ENCEPHALITIS SPORADIC LOW % INFECTIONS -> CLINICAL CASES NOT ALL CASES -> MAJOR DISEASE PROBABLY UNDERDIAGNOSED
  • 448. EASTERN EQUINE ENCEPALITIS Reservoir:birds Vector: mosquito Sentinels – horse,quail, turkey CDC <15, >50yrs at higher risk CFR ~35% ~5 cases/year av. togavirus
  • 449. EASTERN EQUINE ENCEPALITIS CDC togavirus
  • 450. WESTERN EQUINE ENCEPALITIS Reservoir:birds Vector: mosquito Sentinels – horse,quail, turkey Children at higher risk CFR 3-5% togavirus No human cases recently
  • 451. VENEZUELAN EQUINE ENCEPALITIS Reservoir: horse, small mammals Vector: mosquito Mild disease in man togavirus
  • 452. WEST NILE VIRUS Reservoir: birds Vector: mosquito flavivirus http://www.cdc.gov/ncidod/dvbid/westnile/
  • 453. WEST NILE VIRUS Symptoms: – Fever – Meningitis – Encephalitis More rarely: – Acute flaccid paralysis  poliomyelitis - inflammation spinal cord flavivirus http://www.cdc.gov/ncidod/dvbid/westnile/
  • 454. West Nile VirusFor every ~150 people infected – ~30 mild symptoms  mild fever headache, body ache, maybe rash – may never see physician, even if do, may not be diagnosed – ~1 severe illness  e.g. encepalitis, meningitis, high fever, stiff neck, stupor, disorientation, coma, tremors, convulsions, muscle weakness – frequency of flaccid paralysis unknown, but less than frequency of encephalitis
  • 455. WEST NILE VIRUSCase fatality ratio: Higher in elderly Most fatalities over 50 yrs age Peaks about Aug- Sept flavivirus
  • 456. ST. LOUIS ENCEPHALITIS Second commonest mosquito borne disease in US Reservoir: birds – Man usually dead end host Vector: mosquito <1% infections clinical Elderly at higher risk flavivirus CFR 3-25% ~120 cases/year av.
  • 457. CALIFORNIA SEROGROUP ENCEPHALITIS (includes La Crosse virus) Recently commoner in eastern US Reservoir: small mammals Vector: mosquitos Children at higher risk Low CFR ~80 cases/year av. bunyavirus
  • 458. 2000 - 2 cases in SC, Charleston area La Crosse life cycle
  • 459. ARBOVIRUSES – FEVER AND HEMORRHAGIC FEVERFAMILY MAIN DISTRIBUTIO DISEASES NFLAVIVIRIDAEDengue fever, hemorrhagic fever World wide,Yellow fever especially tropics hemorrhagic fever Africa, S. and C. AmericaREOVIRIDAEColorado tick fever fever North America
  • 460. COLORADO TICK FEVERVector: tick Mild disease in man Fever, rash, arthralgia RMSF important consideration in differential Reovirus fami diagnosis
  • 461. World Distribution of Dengue 1999Areas infested with Aedes aegyptiAreas with Aedes aegypti and recent epidemic dengue flaviviru
  • 462. DENGUE FEVER jungle cycle (monkeys-mosquitos) urban cycle (man-mosquitos) rapidly increasing disease in tropics approx. 100-200 cases/yr in US due to import – occasional indigenous transmission 50-100million cases per year worldwide flaviviru
  • 463. Reported Cases of DHF in the Americas, 1970 - 1999 60 50Reported Cases (Thousands) 40 30 20 10 0 1970s 1980s 1990s* * Provisional data through 1999
  • 464. Dengue virus Mosquito feeds / acquires virus Viremia 0 5 8 12 ILLNESS CDCHuman #1
  • 465. DENGUE FEVER fever headache retro-orbitalpain myalgia, arthralgia bone-ache „breakbone fever‟ sometimes rash may look like flu, measles, rubella more rarely encephalitis flaviviru
  • 466. DENGUE HEMORRHAGIC FEVER/DENGUE SHOCK SYNDROME hemorrhages plasma leakage hemoconcentration hypotension circulatory failure shock flavivirus
  • 467. DHF - petechiae CDC
  • 468. Dengue hemorrhagic fever - pleural ef CDCVaughn DW et al. J Infect Dis 1997; 176:322-30.
  • 469. DENGUE HEMORRHAGIC FEVER immunopathological4 serotypes (1, 2, 3, 4) maternal antibody flaviviru
  • 470. DENGUE HEMORRHAGIC FEVER Immune enhancement hypothesis – more mononuclear cells infected – infected monocytes release vasoactive mediators – increased vascular permeability – hemorrhagic symptoms flaviviru
  • 471. DENGUE HEMORRHAGIC FEVER children more severe disease do not give aspirin – because of anticoagulant affect CFR depends on rapid response – can be as low as 1% flaviviru
  • 472. YELLOW FEVER jungle and urban cycles hemorrhages degeneration liver, kidney, heart CFR 50% Vaccine CDC – important to consider in travel to areas with yellow fever flaviviru