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Influenza a h1 ni latest Influenza a h1 ni latest Presentation Transcript

  • Just-in-Time LectureInfluenza A(H1N1) (Swine Flu): A Global Outbreak (Version 11, first JIT lecture issued April 26)Tuesday, May 26, 2009 (01:30 AM EST)
    Rashid A. Chotani, MD, MPH, DTM
    Adjunct Assistant Professor
    Uniformed Services University of the Health Sciences (USUHS)
    240-367-5370
    chotani@gmail.com
    • RNA, enveloped
    • Viral family: Orthomyxoviridae
    • Size:
    80-200nm or .08 – 0.12 μm (micron) in diameter
    • Three types
    • A, B, C
    • Surface antigens
    • H (haemaglutinin)
    • N (neuraminidase)
    Virus
    Credit: L. Stammard, 1995
  • Structure of the influenza hemagglutinin monomer
    HA monomer. Sites A-E are immunodominant epitopes (From Fields Virology, 2nd ed, Fields & Knipe, eds, Raven Press, 1990, Fig.40-4)
  • Structure of the influenza hemagglutinin trimer
    HA trimer. (From Fields Virology, 2nd ed, Fields & Knipe, eds, Raven Press, 1990, Fig.39-6)
  • Influenza A reservoir
    Wild aquatic birds are the main reservoir of influenza A viruses. Virus transmission has been reported from weild waterfowl to poultry, sea mammals, pigs, horses, and humans. Viruses are also transmitted between pigs and humans, and from poultry to humans. Equine influenza viruses have recently been transmitted to dogs. (From Fields Vriology (2007) 5th edition, Knipe, DM & Howley, PM, eds, Wolters Kluwer/Lippincott Williams & Wilkins, Philadelphia, Fig 48.1)
  • Influenza replication
    Replication of influenza A virus. After binding (1) to sialic acid-containing receptors, influenza is endocytosed and fuses (2) with the vesicle membrane. Unlike for most other RNA viruses, transcription (3) and replication (5) of the genome occur in the nucleus. Viral proteins are synthesized (4), helical nucleocapsid segments form and associate (6) with the M1 protein-lined membranes containing M2 and the HA and NA glycoproteins. The virus buds (7) from the plasma membrane with 11 nucleocapsid segments. (-), Negative sense; (+), positive sense; ER, endoplasmic reticulum. (From Medical Microbiology, 5th ed., Murray, Rosenthal & Pfaller, Mosby Inc., 2005, Figure 60-2.)
  • Influenza pathogenesis
    Pathogenesis of influenza A virus. The symptoms of influenza are caused by viral pathologic and immunopathologic effects, but the infection may promote secondary bacterial infection. CNS, Central nervous system. (From Medical Microbiology, 5th ed., Murray, Rosenthal & Pfaller, Mosby Inc., 2005, Figure 60-3.)
  • Definitions
    General
    Epidemic – a located cluster of cases
    Pandemic – worldwide epidemic
    Antigenic drift
    Changes in proteins by genetic point mutation & selection
    Ongoing and basis for change in vaccine each year
    Antigenic shift
    Changes in proteins through genetic reassortment
    Produces different viruses not covered by annual vaccine
  • Survival of Influenza Virus Surfaces and Affect of Humidity & Temperature*
    Hard non-porous surfaces 24-48 hours
    Plastic, stainless steel
    Recoverable for > 24 hours
    Transferable to hands up to 24 hours
    Cloth, paper & tissue
    Recoverable for 8-12 hours
    Transferable to hands 15 minutes
    Viable on hands <5 minutes only at high viral titers
    Potential for indirect contact transmission
    *Humidity 35-40%, Temperature 28C (82F)
    Source: Bean B, et al. JID 1982;146:47-51
  • Influenza
    The Normal Burden of Disease
    Seasonal Influenza
    Globally: 250,000 to 500,000 deaths per year
    In the US (per year)
    ~35,000 deaths
    >200,000 Hospitalizations
    $37.5 billion in economic cost (influenza & pneumonia)
    >$10 billion in lost productivity
    Pandemic Influenza
    An ever present threat
  • Swine Influenza A(H1N1)Introduction
    Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza that regularly cause outbreaks of influenza among pigs
    Most commonly, human cases of swine flu happen in people who are around pigs
    Swine flu viruses do not normally infect humans, however, human infections with swine flu do occur, and cases of human-to-human spread of swine flu viruses have been documented
  • Swine Influenza A(H1N1) History in US
    A swine flu outbreak in Fort Dix, New Jersey, USA occurred in 1976 that caused more than 200 cases with serious illness in several people and one death
    More than 40 million people were vaccinated
    However, the program was stopped short after over 500 cases of Guillain-Barre syndrome, a severe paralyzing nerve disease, were reported
    30 people died as a direct result of the vaccination
    In September 1988, a previously healthy 32-year-old pregnant woman in Wisconsin was hospitalized for pneumonia after being infected with swine flu and died 8 days later.
    From December 2005 through February 2009, a total of 12 human infections with swine influenza were reported from 10 states in the United States
  • Swine Influenza A(H1N1) Transmission to Humans
    Through contact with infected pigs or environments contaminated with swine flu viruses
    Through contact with a person with swine flu
    Human-to-human spread of swine flu has been documented also and is thought to occur in the same way as seasonal flu, through coughing or sneezing of infected people
  • Swine Influenza A(H1N1) Transmission Through Species
    Human Virus
    Avian Virus
    Avian/Human
    Reassorted Virus
    Swine Virus
    Reassortment in Pigs
  • Swine Influenza A(H1N1) March 2009Timeline
    In March and early April 2009, Mexico experienced outbreaks of respiratory illness and increased reports of patients with influenza-like illness (ILI) in several areas of the country
    April 12, the General Directorate of Epidemiology (DGE) reported an outbreak of ILI in a small community in the state of Veracruz to the Pan American Health Organization (PAHO) in accordance with International Health Regulations
    April 17, a case of atypical pneumonia in Oaxaca State prompted enhanced surveillance throughout Mexico
    April 23, several cases of severe respiratory illness laboratory confirmed as influenza A(H1N1) virus infection were communicated to the PAHO
    Sequence analysis revealed that the patients were infected with the same strain detected in 2 children residing in California
    Samples from the Mexico outbreak match swine influenza isolates from patients in the United States
    Source: CDC
  • Swine Influenza A(H1N1) March 2009Facts
    Virus described as a new subtype of A/H1N1 not previously detected in swine or humans
    CDC determines that this virus is contagious and is spreading from human to human
    The virus contains gene segments from 4 different influenza types:
    North American swine
    North American avian
    North American human and
    Eurasian swine
  • Swine Influenza A(H1N1) US Response
    The Strategic National Stockpile (SNS) is releasing one-quarter of its
    Anti-viral drugs
    Personal protective equipment and
    Reparatory protection devices
    President Obama today asked Congress for an additional $1.5 billion to fight the swine flu
    On April 27, 2009, the CDC issued a travel advisory that recommends against all non-essential travel to Mexico
    Source: CDC
  • Swine Influenza A(H1N1) Global Response
    The WHO raised the alert level to Phase 5
    WHO’s alert system was revised after Avian influenza began to spread in 2004, and April 27 was the first time it was raised above Phase 3 and on April 29 to Phase 5.
    European Union (EU) issued a travel advisory to the 27 EU member countries recommending that “non-essential” travel to affected parts of the U.S. and Mexico be suspended
    Source: WHO
  • Swine Influenza A(H1N1) May 25, 2009Status Update
    MEXICO: March 01-May 22, a total of
    4,174 Laboratory confirmed cases, with 80 deaths and 1311 hospitalizations (for pneumonia) reported in 32 of 32 States
    UNITED STATES: March 28-May 25, a total of 
    6,764 Laboratory confirmed cases, with 10 deaths (Arizona 3; Missouri 1; New York 1; Texas 3; Utah 1 and; Washington 1) from 48 States (including District of Columbia)
    Over 100 Hospitalizations
    Most cases mild
    CANADA: As of May 25, a total of
    921 Laboratory confirmed cases, with one deaths (1 Alberta) from 10 of 13 States
    116 new Laboratory confirmed cases May 25
    Most cases mild
    Source: Secretaria de Salud, Mexico, CDC, Public Health Agency of Canada, European CDC, WHO
  • Swine Influenza A(H1N1) May 25, 2009Status Update
    EUROPEAN UNION & EFTA COUNTRIES: April 27- May 25, a total of
    360 Laboratory confirmed cases, with no deaths from 19 countries
    11 confirmed cases reported on May 24
    130 in-country transmissions
    Vast majority of cases reported between 20-49 years of age
    Most cases (except 1) report mild disease
    GLOBALLY: March 1-May 25, a total of
    12,727 Laboratory confirmed cases, from 46 countries
    92 Deaths among laboratory confirmed cases from 4 countries
    Mexico: 80 deaths
    US: 10 deaths
    Canada: 01 death
    Costa Rica: 01 death
    Source: Secretaria de Salud, Mexico, CDC, Public Health Agency of Canada, European CDC, WHO
  • Swine Influenza A(H1N1)MMRW Report, April 28
    MMWR, April 28, 2009 / 58(Dispatch);1-3
    47 patients reported to CDC with known ages (out of 64) the median age was 16 years (range: 3-81 years)
    38 (81%) were aged <18 years
    51% of cases were in males
    Of the 25 cases with known dates of illness onset, onset ranged from March 28 to April 25
    Five patients hospitalized
    Of 14 patients with known travel histories
    3 had traveled to Mexico
    40 of 47 patients (85%) had not been linked to travel or to another confirmed case
    Source: CDC. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm58d0428a2.htm
  • Swine Influenza A(H1N1)MMRW Report, April 30
    MMWR, April 30, 2009 / 58(Dispatch);1-3
    NYC school (high school A)
    2,686 students and 228 staff members
    April 23-24, 222 students visited the school nursing office and left school because of illness
    DOHMH collect nasopharyngeal swabs from any symptomatic students
    April 24 (Friday), DOHMH collected nasopharyngeal swabs from five newly symptomatic students identified by the school nurse and four newly symptomatic students identified at a nearby physician's office
    April 27, School closed
    DOHMH also provided nasopharyngeal test kits to selected physicians' offices in the vicinity of high school A
    April 26, 7 of 9 specimens collected on April 24 were positive for the new strain of influenza
    April 26-28, 37 (88%) of 42 specimens collected tested positive, bringing the total number of confirmed cases to 44
    April 27 DOHMH conducted telephone interviews with the 44 patients
    Median age was 15 years (range: 14-21 years)
    All were students, with the exception of one student teacher aged 21 years
    Thirty-one (70%) of the 44 were female
    Thirty (68%) were non-Hispanic white; seven (16%) were Hispanic; two (5%) were non-Hispanic black; and five (11%) were other races
    Four patients reported travel outside NYC within the United States in the week before symptom onset, and an additional patient traveled to Aruba in the 7 days before symptom onset. None of the 44 patients reported recent travel to California, Texas, or Mexico
    Source: CDC. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm58d0428a2.htm
  • Swine Influenza A(H1N1) MMRW Report, April 30
    MMWR, April 30, 2009 / 58(Dispatch);1-3
    Illness onset dates ranged from April 20 to April 24
    10 (23%) of the patients had illness onset on April 22, and 28 (64%) had illness onset on April 23 (Figure).
    Among 35 patients who reported a maximum temperature, the mean was 102.2°F (39.0°C) (range: 99.0-104.0°F [37.2--40.0°C])
    In total, 42 (95%) patients reported subjective fever plus cough and/or sore throat, meeting the CDC definition for influenza-like illness (ILI)
    At the time of interview on April 27, 37 patients (84%) reported that their symptoms were stable or improving, three (7%) reported worsening symptoms (two of whom later reported improvement), and four (9%) reported complete resolution of symptoms
    Only one reported having been hospitalized for syncope and released after overnight observation
    Source: CDC. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm58d0428a2.htm
  • Laboratory-Confirmed Cases of New Influenza A(H1N1) by Countries, May 25, 2009
    12,727 Cases & 92 Deaths
    10
    80
    1
    1
    Chinese Taipei has reported 1 confirmed case of influenza A (H1N1) with 0 deaths. Cases from Chinese Taipei are included in the cumulative totals provided in the table above.
  • Global Distribution of Reported Cumulative & Probable Cases of Swine Influenza A(H1N1) by Countries, May 25, 2009 (08:00 GMT)
    US
    6,767 cases
    10 deaths
    Total
    12,727 Cases
    92 deaths
    12,727 Cases & 92 Deaths
    Source: WHO
  • Swine Influenza A(H1N1) USCase Definitions
    A confirmed case of swine influenza A (H1N1) virus infection is defined as a person with an acute febrile respiratory illness with laboratory confirmed swine influenza A (H1N1) virus infection at CDC by one or more of the following tests:
    real-time RT-PCR
    viral culture
    A probable case of swine influenza A (H1N1) virus infection is defined as a person with an acute febrile respiratory illness who is:
    positive for influenza A, but negative for H1 and H3 by influenza RT-PCR, or
    positive for influenza A by an influenza rapid test or an influenza immunofluorescence assay (IFA) plus meets criteria for a suspected case
    A suspected case of swine influenza A (H1N1) virus infection is defined as a person with acute febrile respiratory illness with onset
    within 7 days of close contact with a person who is a confirmed case of swine influenza A (H1N1) virus infection, or
    within 7 days of travel to community either within the United States or internationally where there are one or more confirmed swine influenza A(H1N1) cases, or
    resides in a community where there are one or more confirmed swine influenza cases.
    Source: CDC
  • Swine Influenza A(H1N1) USCase Definitions
    Infectious period for a confirmed case of swine influenza A(H1N1) virus infection is defined as 1 day prior to the case’s illness onset to 7 days after onset
    Close contact is defined as: within about 6 feet of an ill person who is a confirmed or suspected case of swine influenza A(H1N1) virus infection during the case’s infectious period
    Acute respiratory illness is defined as recent onset of at least two of the following: rhinorrhea or nasal congestion, sore throat, cough (with or without fever or feverishness)
    High-risk groups: A person who is at high-risk for complications of swine influenza A(H1N1) virus infection is defined as the same for seasonal influenza (see Reference)
    Source: CDC
  • Swine Influenza A(H1N1) Guidelines for Clinicians
    Clinicians should consider the possibility of swine influenza virus infections in patients presenting with febrile respiratory illness who
    live in areas where human cases of swine influenza A(H1N1) have been identified or
    have traveled to an area where human cases of swine influenza A(H1N1) has been identified or
    have been in contact with ill persons from these areas in the 7 days prior to their illness onset
    If swine flu is suspected, clinicians should obtain a respiratory swab for swine influenza testing and place it in a refrigerator (not a freezer)
    once collected, the clinician should contact their state or local health department to facilitate transport and timely diagnosis at a state public health laboratory
    Source: CDC
  • Swine Influenza A(H1N1) Guidelines for Clinicians
    Signs and Symptoms
    Influenza-like-illness (ILI)
    Fever, cough, sore throat, runny nose, headache, muscle aches. In some cases vomiting and diarrhea. (These cases had illness onset during late March to mid-April 2009)
    Cases of severe respiratory disease, requiring hospitalization including fatal outcomes, have been reported in Mexico
    The potential for exacerbation of underlying chronic medical conditions or invasive bacterial infection with swine influenza virus infection should be considered
    Non-hospitalized ill persons who are a confirmed or suspected case of swine influenza A (H1N1) virus infection are recommended to stay at home (voluntary isolation) for at least the first 7 days after illness onset except to seek medical care
    Source: CDC
  • Swine Influenza A(H1N1) Guidelines for Clinicians
    FDA Issues Authorizations for Emergency Use (EUAs) of Antivirals
    On April 27, 2009, the U.S. Food and Drug Administration (FDA) issued EUAs in response to requests by the Centers for Disease Control and Prevention (CDC) for the swine flu outbreak
    One of the reasons the EUAs could be issued was because the U.S. Department of Health and Human Services (HHS) declared a public health emergency on April 26, 2009
    The swine influenza EUAs aid in the current response:
    Tamiflu:Allow for Tamiflu to be used to treat and prevent influenza in children under 1 year of age, and to provide alternate dosing recommendations for children older than 1 year. Tamiflu is currently approved by the FDA for the treatment and prevention of influenza in patients 1 year and older.
    Tamiflu and Relenza: Allow for both antivirals to be distributed to large segments of the population without complying with federal label requirements that would otherwise apply to dispensed drugs and to be accompanied by written information about the emergency use of the medicines.
    Source: FDA
  • Swine Influenza A(H1N1) Biosafety Guidelines for Laboratory Workers
    Diagnostic work on clinical samples from patients who are suspected cases of swine influenza A (H1N1) virus infection should be conducted in a BSL-2 laboratory
    All sample manipulations should be done inside a biosafety cabinet (BSC)
    Viral isolation on clinical specimens from patients who are suspected cases of swine influenza A (H1N1) virus infection should be performed in a BSL-2 laboratory with BSL-3 practices (enhanced BSL-2 conditions)
    Additional precautions include:
    recommended personal protective equipment (based on site specific risk assessment)
    respiratory protection - fit-tested N95 respirator or higher level of protection
    shoe covers
    closed-front gown
    double gloves
    eye protection (goggles or face shields)
    Waste
    all waste disposal procedures should be followed as outlined
    in your facility standard laboratory operating procedures
    Source: CDC
  • Swine Influenza A(H1N1) Biosafety Guidelines for Laboratory Workers
    Appropriate disinfectants
    70 per cent ethanol
    5 per cent Lysol
    10 per cent bleach
    All personnel should self monitor for fever and any symptoms. Symptoms of swine influenza infection include diarrhea, headache, runny nose, and muscle aches
    Any illness should be reported to your supervisor immediately
    For personnel who had unprotected exposure or a known breach in personal protective equipment to clinical material or live virus from a confirmed case of swine influenza A (H1N1), antiviral chemoprophylaxis with zanamivir or oseltamivir for 7 days after exposure can be considered
    Source: CDC
  • Swine Influenza A(H1N1) Biosafety Guidelines for Laboratory Workers
    FDA Issues Authorizations for Emergency Use (EUAs) of Diagnostic
    Tests
    On April 27, 2009, the U.S. Food and Drug Administration (FDA) issued EUAs in response to requests by the Centers for Disease Control and Prevention (CDC) for the swine flu outbreak
    One of the reasons the EUAs could be issued was because the U.S. Department of Health and Human Services (HHS) declared a public health emergency on April 26, 2009
    The swine influenza EUAs aid in the current response:
    Diagnostic Test: Allow CDC to distribute the rRT-PCR Swine Flu Panel diagnostic test to public health and other qualified laboratories that have the equipment and personnel to perform and interpret the results.
    Source: CDC
  • Swine Influenza A(H1N1) Guidelines for General Population
    Covering nose and mouth with a tissue when coughing or sneezing
    Dispose the tissue in the trash after use.
    Handwashing with soap and water
    Especially after coughing or sneezing.
    Cleaning hands with alcohol-based hand cleaners
    Avoiding close contact with sick people
    Avoiding touching eyes, nose or mouth with unwashed hands
    If sick with influenza, staying home from work or school and limit contact with others to keep from infecting them
  • Swine Influenza A(H1N1) Treatment
    No vaccine available
    Antivirals for the treatment and/or prevention of infection:
    Oseltamivir (Tamiflu) or
    Zanamivir (Relenza)
    Use of anti-virals can make illness milder and recovery faster
    They may also prevent serious flu complications
    For treatment, antiviral drugs work best if started soon after getting sick (within 2 days of symptoms)
    Warning! Do NOT give aspirin (acetylsalicylic acid) or aspirin-containing products (e.g. bismuth subsalicylate – Pepto Bismol) to children or teenagers (up to 18 years old) who are confirmed or suspected ill case of swine influenza A (H1N1) virus infection; this can cause a rare but serious illness called Reye’s syndrome. For relief of fever, other anti-pyretic medicationsare recommended such as acetaminophen or non steroidal anti-inflammatory drugs.
    Source: CDC
  • Swine Influenza A(H1N1) Treatment
    Dosing recommendations for antiviral treatment of children younger than 1 year using oseltamivir. Recommended treatment dose for 5 days. <3 months: 12 mg twice daily; 3-5 months: 20 mg twice daily; 6-11 months: 25 mg twice daily
    Dosing recommendations for antiviral chemoprophylaxis of children younger than 1 year using oseltamivir. Recommended prophylaxis dose for 10 days. <3 months: Not recommended unless situation judged critical due to limited data on use in this age group; 3-5 months: 20 mg once daily; 6-11 months: 25 mg once daily
    Source: CDC
  • Swine Influenza A(H1N1) Other Protective Measures
    Defining Quarantine vs. Isolation vs. Social-Distancing
    Isolation: Refers only to the sequestration of symptomatic patents either in the home or hospital so that they will not infect others
    Quarantine: Defined as the separation from circulation in the community of asymptomatic persons that may have been exposed to infection
    Social-Distancing: Has been used to refer to a range of non-quarantine measures that might serve to reduce contact between persons, such as, closing of schools or prohibiting large gatherings
    Source: CDC
  • Swine Influenza A(H1N1) Other Protective Measures
    Personnel Engaged in Aerosol Generating Activities
    CDC Interim recommendations:
    Personnel engaged in aerosol generating activities (e.g., collection of clinical specimens, endotracheal intubation, nebulizer treatment, bronchoscopy, and resuscitation involving emergency intubation or cardiac pulmonary resuscitation) for suspected or confirmed swine influenza A (H1N1) cases should wear a fit-tested disposable N95 respirator
    Pending clarification of transmission patterns for this virus, personnel providing direct patient care for suspected or confirmed swine influenza A (H1N1) cases should wear a fit-tested disposable N95 respirator when entering the patient room
    Respirator use should be in the context of a complete respiratory protection program in accordance with Occupational Safety and Health Administration (OSHA) regulations.
    Source: CDC
  • Swine Influenza A(H1N1) Other Protective Measures
    Infection Control of Ill Persons in a Healthcare Setting
    Patients with suspected or confirmed case-status should be placed in a single-patient room with the door kept closed.  If available, an airborne infection isolation room (AIIR) with negative pressure air handling with 6 to 12 air changes per hour can be used. Air can be exhausted directly outside or be recirculated after filtration by a high efficiency particulate air (HEPA) filter. For suctioning, bronchoscopy, or intubation, use a procedure room with negative pressure air handling.
    The ill person should wear a surgical mask when outside of the patient room, and should be encouraged to wash hands frequently and follow respiratory hygiene practices. Cups and other utensils used by the ill person should be washed with soap and water before use by other persons. Routine cleaning and disinfection strategies used during influenza seasons can be applied to the environmental management of swine influenza.
    Source: CDC
  • Swine Influenza A(H1N1) Other Protective Measures
    Infection Control of Ill Persons in a Healthcare Setting
    Standard, Droplet and Contact precautions should be used for all patient care activities, and maintained for 7 days after illness onset or until symptoms have resolved.  Maintain adherence to hand hygiene by washing with soap and water or using hand sanitizer immediately after removing gloves and other equipment and after any contact with respiratory secretions.
    Personnel providing care to or collecting clinical specimens from suspected or confirmed cases should wear disposable non-sterile gloves, gowns, and eye protection (e.g., goggles) to prevent conjunctival exposure.
    Source: CDC
  • Types of Protective Masks
    Surgical masks
    Easily available and commonly used for routine surgical and examination procedures
    High-filtration respiratory mask
    Special microstructure filter disc to flush out particles bigger than 0.3 micron. These masks are further classified:• oil proof• oil resistant• not resistant to oil
    The more a mask is resistant to oil, the better it is
    The masks have numbers beside them that indicate their filtration efficiency. For example, a N95 mask has 95% efficiency in filtering out particles greater than 0.3 micron under normal rate of respiration.
    The next generation of masks use Nano-technologywhich are capable of blocking particles as small as 0.027 micron.
  • Summary
    WHO raised the alert level to Phase 5 on April 29, 2009
    There is a disparity between the % case-fatality-rate between Mexico (1.91%), Canada (0.11%) and USA (0.15%)
    The overall global case-fatality (12,727 cases and 92 deaths) is 0.72%
    ~ 1,500 cases worldwide (reported) needed hospitalization
    Majority in Mexico
    Epidemiological Data
    US
    Median Age 16 years (range: 1-81 years)
    Over 80% of the cases in <18 years
    60% female; 40% Male
    Mexico
    Majority of the cases reported in health young adults
    77.5% of the deaths were reported in healthy young adults, 20-54 years
    Individuals 60+ seem to be protected as the number of cases and have a lower case-fatality compared to the rest of the population
    56% female; 44% Male
    EU
    Majority of the cases reported in health young adults (20-29 years).
    In-country transmission (36%) has been documented
    No vaccine is available
    Anti-virals available
  • Timeline of Emergence
    Influenza A Viruses in Humans
    Reassorted Influenza virus (Swine Flu)
    H1
    1976 Swine Flu Outbreak, Ft. Dix
    Avian
    Influenza
    H7
    H9
    H5
    H5
    H1
    H3
    H2
    H1
    2009
    1918
    1957
    1968
    1977
    1997
    2003
    Asian
    Influenza
    H2N2
    Hong
    Kong
    Influenza
    H3N2
    Russian
    Influenza
    Spanish
    Influenza
    H1N1
    1998/9
  • Lessons Learned formPast Pandemics
    First outbreaks March 1918 in Europe, USA
    Highly contagious, but not deadly
    Virus traveled between Europe/USA on troop ships
    Land, sea travel to Africa, Asia
    Warning signal was missed
    August, 1918 simultaneous explosive outbreaks in in France, Sierra Leone, USA
    10-fold increase in death rate
    Highest death rate ages 15-35 years
    Cytokine Storm?
    Deaths from primary viral pneumonia, secondary bacterial pneumonia
    Deaths within 48 hours of illness
    Coincident severe disease in pigs
    20-40 million killed in less than 1 year
    World War I –8.3 million military deaths over 4 years
    25-35% of the world infected
  • Lessons Learned formPast Pandemics
    Pandemics are unpredictable
    Mortality, severity of illness, pattern of spread
    A sudden, sharp increase in the need for medical care will always occur
    Capacity to cause severe disease in nontraditional groups is a major determinant of pandemic impact
    Epidemiology reveals waves of infection
    Ages/areas not initially infected likely vulnerable in future waves
    Subsequent waves may be more severe
    1918- virus mutated into more virulent form
    1957 schoolchildren spread initial wave, elderly died in second wave
    Public health interventions delay, but do not stop pandemic spread
    Quarantine, travel restriction show little effect
    Does not change population susceptibility
    Delay spread in Australia— later milder strain causes infection there
    Temporary banning of public gatherings, closing schools potentially effective in case of severe disease and high mortality
    Delaying spread is desirable
    Fewer people ill at one time improve capacity to cope with sharp increase in need for medical care
  • Conclusion/Recommendations
    Past experience with pandemics have taught us that the second wave is worse than the first causing more deaths due to:
    Primary viral pneumonia, Acute Respiratory Distress Syndrome (ARDS), & Secondary bacterial infections, particularly pneumonia
    Fortunately compared to the past now we have anti-virals and antibiotics (to treat secondary bacterial infections)
    Though difficult, there is likelihood that there will be a vaccine for this strain by the emergence of the second wave
    In the US each year ~35,000 deaths are attributed to influenza resulting in >200,000 hospitalizations, costing $37.5 billion in economic cost (influenza & pneumonia) and >$10 billion in lost productivity
    Based upon past experience and the way the current H1N1 outbreak is acting (current wave is contagious, spreading rapidly and in Mexico and Canada based upon preliminary data affecting the healthy), there is a likelihood that come fall there might be a second wave which could be more virulent
  • Conclusion/Recommendations
    At present four death due to H1N1 strain has been reported outside Mexico.
    • The disease, though spreading rapidly across the globe, is of a mild form (exception Mexico)
    • Most people do not have immunity to this virus and, as it continues to spread. More cases, more hospitalizations and some more deaths are expected in the coming days and weeks
    • Disease seems to be affecting the healthy strata of the population based upon epidemiological data from Mexico and EU
    • 60 years and above age group seems to show some protection against this strain suggesting past exposure and some immunity
    Each locality/jurisdiction needs to
    Have enhanced disease and virological surveillance capabilities
    Develop a plan to house large number of severely sick and provide care if needed to deal with mildly sick at home (voluntary quarantine)
    Healthcare facilities/hospitals need to focus on increasing surge capacity and stringent infection prevention/control
    General population needs to follow basic precautions
  • Conclusion/Recommendations
    In the Northern Hemisphere influenza viral transmission traditionally stops by the beginning of May but in pandemic years (1957) sporadic outbreaks occurred during summer among young adults
    Likelihood that
    This wave will fade in North America within the next 1-3 weeks (influenza virus cannot survive high humidity or temperature)
    Will reappear in autumn in North America with the likelihood of being a highly pathogenic second wave
    Will continue to circulate and cause disease in the Southern Hemisphere
    Border Closure and Travel Restrictions:
    The disease has already crossed borders and continents, thus, border closure or travel restrictions will not change the course of the spread of disease
    • Most recently, the 2003 experience with SARS demonstrated the ineffectiveness of such measures
    • In China, 14 million people were screened for fever at the airport, train stations, and roadside checkpoints, but only 12 were found to have probable SARS
    • Singapore reported that after screening nearly 500,000 air passengers, none were found to have SARS
    • Passive surveillance methods (in which symptomatic individuals report illness) can be important tools
  • Conclusion/Recommendations
    School Closures:
    Preemptive school closures will merely delay the spread of disease
    Once schools reopen (as they cannot be closed indefinitely), the disease will be transmitted and spread
    Furthermore, this would put unbearable pressure on single-working parents and would be devastating to the economy (as children cannot be left alone)
    Closure after identification of a large cluster would be appropriate as absenteeism rate among students and teachers would be high enough to justify this action
    High priority should be given to develop and include the present “North American” (swine) influenza A(H1N1) virus in next years vaccine. A critical look at manufacturing capacity is called for
    It is imperative to appreciate that “times-have-changed”
    • Though this strain has spread very quickly across the globe and seems to be highly infectious, today we are much better prepared than 1918. There is better surveillance, communication, understanding of infection control, anti-virals, antibiotics and advancement in science and resources to produce an affective vaccine