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Arboviral outbreak


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Arboviral outbreak

Arboviral outbreak

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  • 1. ARBOVIRAL OUTBREAK A DEADLY SCOURGE Role of the Microbiologists in the investigation of an outbreak Dr K.Prasanthi , MD Department of Microbiology, Gandhi Medical College , Secunderabad INDIA Dr.K.Prasanthi MD
  • 2. Introduction
    • Arboviruses contributing to a large proportion of total burden of infections
    • Viruses are entering into new territories , are more virulent than earlier and becoming endemic in new regions
      • Ex :Chikungunya ,Dengue , West nile, JE , KFD, Chandipura which were almost not existing in India , but now reported from all parts of the country
    • Severity of these illnesses is totally depends on the efficacy of the surveillance system
    Dr.K.Prasanthi MD
  • 3. Perspectives
    • Arboviruses :
      • large group (more than 400) of enveloped RNA viruses which are transmitted primarily (but not exclusively) by Arthropod vectors (mosquitoes, sand-flies, fleas, ticks, lice, etc)
    • Humans are infected only if they get in the way of the viral natural cycle by entering areas where the viruses are prevalent and being bitten by an infected arthropod
    • Infection is often in apparent or trivial
      • but some of these viruses can cause very severe , even fatal illnesses including febrile illnesses often with rashes and arthritis, infections of the nervous system and hemorrhagic fevers
    Dr.K.Prasanthi MD
  • 4. What is an Outbreak
    • Appearance of an unusual number of cases of a disease or condition in a population in a given period of time and place
      • Outbreaks of Japanese Encephalitis were reported largely from India and Nepal
      • There were also several outbreaks of Dengue, Chikungunya and JE in recent years
        • Resulted in considerable morbidity and mortality
    Dr.K.Prasanthi MD
    • An epidemic of viral encephalitis was reported in 2005 in India. Where 5,737 persons were affected and 1,344 persons died.
    • More than 60 outbreaks of Dengue have occurred since 1956
    • There was a huge outbreak of Dengue in 2003 with 12,754 cases and 215 deaths
    • In 2006 outbreak it was estimated that 10,344 cases and 162 deaths due to severe forms of Dengue (DSS/DHF) had taken place.
    • Chikungunya fever , which is responsible for significant human morbidity for several years, was first reported in 1963 in Calcutta followed by epidemics in Tamilnadu, Andhra Pradesh ,ending in Maharashtra in 1973 after 8 years of quiescence
    • After 32 years in 2005 the disease has reemerged causing 1.3 million cases in 13 states of India including Andhra Pradesh
    Dr.K.Prasanthi MD
  • 6. Preparedness: An Essential Element
    • Because widespread epizootic activity , larger outbreaks of arboviral infections and human illness are possible if adequate surveillance, prevention activities and mosquito control measures are not established and maintained
    • Private practitioners , the major service providers in India and a frontline to control many diseases are failing to guide people to take preventive measures
    Dr.K.Prasanthi MD
  • 7. Preparedness Is Essential
    • Integrated and accelerated action to reduce mortality by these threatening diseases is done by strong interaction, commitment , knowledge, training of various health departments in the investigation of any disease outbreak
    • The involvement and expertise of infectious disease physicians, microbiologists, and public health practitioners are essential to the early detection and management of epidemics
    Dr.K.Prasanthi MD
  • 8.
    • Although clinical diagnosis is useful, Laboratory confirmation will be more meaningful .
    • Rapid alert to outbreak situations may be accelerated with microbiology laboratories integrated into national and supra-national global surveillance programmes
    Dr.K.Prasanthi MD
  • 9. Causes of Arboviral epidemics
    • Travel of susceptible individuals into an endemic area where the infectious disease exists
    • Introduction of a new arbovirus by humans or animals traveling from an endemic area into a susceptible human population in whom the disease is not endemic, or
    • When host susceptibility and response are modified by immunosuppression
    Dr.K.Prasanthi MD
  • 10. Objectives of an outbreak investigation
    • Identify the responsible etiologic agent .
    • Find the source of infection by studying the occurrence of the disease among persons or in a place or time, as well as determining specific attack rates.
    • Formulate recommendations to prevent further transmission
    Dr.K.Prasanthi MD
  • 11. Responsibilities of Microbiology lab
    • Rapid identification of the cause of outbreaks
    • Confirming the diagnosis of disease outbreak
    • Characterization of the infectious agents responsible
    • Tracing the source of infection
    • Detecting the Carriers and
    • Treatment monitoring
    Dr.K.Prasanthi MD
  • 12. An integrated disease surveillance system
    • Surveillance involves the scrutiny of all aspects of the occurrence and spread of a disease so that one can bring about effective control
    • Laboratory confirmation :
      • Provides scientific answers to basic epidemiological questions
    Dr.K.Prasanthi MD
  • 13. Role of Microbiologist
    • Ongoing process
    • Passive surveillance
      • of routine diseases and give early confirmation or
    • Active surveillance
      • in the case of out breaks and
    • Epidemiological disease surveillance
    Dr.K.Prasanthi MD
  • 14. Planning an investigation
    • The primary step for a microbiologist in planning an investigation of an outbreak is
      • to establish a goal
      • to identify the causative agent as in arboviral outbreaks
    • The entire investigation, planning, gathering of data and sample collection must be designed to minimize economic burden
    Dr.K.Prasanthi MD
  • 15. Syndromic approach
    • Syndromic approach is followed for screening the cases for investigation of an arboviral outbreak
    • Tests has to be done to identify the pathogen for :
      • Acute hemorrhagic fever syndromes by screening for Dengue, hanta virus, KFD, West Nile, malaria,
      • Acute neurological syndrome for AFP, JE, Rabies, and
      • Acute systemic syndrome for Typhoid ,malaria, viral hepatitis, dengue, leptospirosis ,Chikungunya etc
    Dr.K.Prasanthi MD
  • 16. Broad categories of presentation
    • fever Less than seven days duration without any localizing signs ,With rash , With altered sensorium, Bleeding from skin or mucous membrane or
    • fever for more than seven days with or without localizing signs, rash, arthritis or any unusual events causing death or hospitalization
    Dr.K.Prasanthi MD
  • 17. Critical elements of Laboratory support
    • Communication
    • Specimen collection and transport and
    • Specimen processing
    Dr.K.Prasanthi MD
  • 19. Communication
    • A two way communication must be established between the outbreak investigation team and the laboratory
    Dr.K.Prasanthi MD
  • 20. Communication
    • The laboratory must be informed when there is a suspected outbreak and the nature of that outbreak
    • There must be effective inter sectorial communications between different laboratories where veterinary / entomology investigations are handled , which provides the information about nature of the vector and the possible virus isolated from the vector body
    • In turn the lab must communicate the results of the investigation promptly and accurately to the out break investigation team
    Dr.K.Prasanthi MD
  • 21. Collection “ quality begins with the specimen ”
    • Laboratory must be provided with
      • The right specimen
      • Taken at right time
      • Stored & transported in the right way
    • Arrange for an outbreak investigation kit with all the required material
    • Follow the operational guide lines provided during collection of clinical samples
    • Ensure that attending medical staff is knowledgeable / communicated about various aspects of sample collection
    Dr.K.Prasanthi MD
  • 22. Outbreak investigation kit
    • Disposable storage vials (5ml)
    • Disposable sample collection vials
    • Stool culture bottle
    • Throat swabs
    • blood culture bottles
    • viral transport medium
    • Cary Blair medium
    • Stuart's transport medium
    • Tourniquet , Gloves , Masks
    • Disposable gowns
    • Puncture proof discarding bags (disposable)
    • Vacutainer (plain and EDTA)
    • Syringes and needles
    • Spirit swabs , alcohol swabs
    • Band-aid
    • Vaccine carrier with ice-packs
    • Spirit lamp, Match-box
    • Test tube rack, Centrifuge tubes
    • Lancets
    • Slides and cover slips
    • Rubber bands
    • Ziploc plastic bags
    • Absorbent material (tissue paper, cotton wool, newspaper)
    Dr.K.Prasanthi MD
  • 23. Required Specimens
    • Specimens usually required in a suspected Arboviral outbreak are :
      • Whole Blood
      • Serum
      • CSF
      • Post mortem samples like tissues
    Dr.K.Prasanthi MD
  • 24. CSF
    • Collected following all aseptic precautions
    • Divide into 3-4 portions
      • 1 st Bottle : Biochemical Analysis
      • 2 nd bottle : Gram staining and culture
      • 3 rd Bottle : cell count etc
      • 4 th Bottle : Serology and virus isolation
    • Do not dilute CSF in VTM
    • Transport with out delay
      • Sent on ice or cold pack insulated containers
    Dr.K.Prasanthi MD
  • 25. Serum
    • Collected in a sterile test tube
    • Allowed to clot
    • Centrifuged and serum separated
    • Transported at 4-8 0 C ( upto 10 days)
    • Paired sera are better
      • 1st sample to be collected during acute stage
      • 2nd sample - After 2-3 weeks
    Dr.K.Prasanthi MD
  • 26. Blood samples
    • For Isolation of virus from blood
    • Lymphocytes & PMN’s are the Commonest intracellular sites for virus multiplication
    • Collected following universal precautions
    • Discard the needles in sharp containers
    • Decontaminate the used syringes
    Dr.K.Prasanthi MD
  • 27. Post mortem samples
    • Biopsy material for relevant tissues
      • Placed in formalin for : HPE
      • Transport medium for microbiological testing
        • sterile saline or viral transport media
    • Specimens in transport media may be transported within 24 hrs at ambient temp
    • Specimens in saline must be transported at 4 - 8 0 C in 48 hours.
    Dr.K.Prasanthi MD
  • 28. Lab form and Labeling samples
    • The lab form should be filled and accompany every sample collected
    • Each patient is given an unique ID number
    • Proper labeling of sample : very important
    Dr.K.Prasanthi MD
  • 29. Storage of the samples
    • Samples should reach the concern lab as early as possible
    • Storage is required when the Laboratory is not in accessible distance , till the collecting boy picks the samples
    • Before storing check again whether all the containers are labeled or not
    • Method of storage
      • for short term storage- refrigerate/ melting ice at 4 0 c
      • delay for more than 48hrs  Freeze at ‘ – 20 0 C’
    Dr.K.Prasanthi MD
  • 30. Transportation
    • Transported to identified laboratory
    • The samples should be labeled properly
    • Accompanied with lab form
      • With demographic and epidemiological data
    • Transport boxes tightly packed
      • Absorbent cotton pads in interior
    • Cold chain maintained
    • Avoid large number of samples in single bag
    Dr.K.Prasanthi MD
  • 31. Laboratory Workup
    • Lab form and specimen label verified on receipt
    • Ensure that in the laboratory :
      • Equipment and reagents required are available and functional
      • Appropriate safety precautions in place
      • Properly trained staff
      • Quality Control Programme in operation
      • Specimen log maintained
      • Communication abilities
    • Access to electronic communication networks for rapid transmission of results and/ or early warning signals
    Dr.K.Prasanthi MD
  • 32. Methods of viral diagnosis
    • Microscopy : Electron Microscope
    • Cell cultures for virus isolation
    • Serology
    • Molecular techniques
    Dr.K.Prasanthi MD
  • 33. Electron Microscope
    • Rapid identification of viruses especially for detection of fastidious & uncultivable viruses
    • Always exclude bacterial , fungal &parasitic etiology by wet mount, Gram’s stain, negative stain and acid fast stain
    • Immune Electron Microscopy : more Sensitivity and specificity
    • Drawbacks : expensive equipment , difficult to maintain , require experienced observer and sensitivity is often low
    Dr.K.Prasanthi MD
  • 34. Cell cultures
    • Gold standard for virus detection
    • Success of cell cultures depends on the
      • selection of cell lines
      • appropriate specimen
      • maintenance of viability & health of inoculated cells
      • expertness in testing for presence of CPE& haemagglutination activity
    Dr.K.Prasanthi MD
  • 35. Serology
    • Most widely used method for detection of arboviral infections
    • Criteria for diagnosing primary Infection include
      • presence of IgM
      • A single high titer of IgG (or total antibody) though helpful but very unreliable
      • A four fold or more increase in titer of IgG or total antibody between acute and convalescent sera is significant
    • False negatives are seen if the patient is in seroconversion period
    • False positives due to cross reactivity of the closely related species
    Dr.K.Prasanthi MD
  • 36. Serology
    • Criteria for diagnosing reinfection is
      • Four fold or more increase in titer of IgG or total antibody between acute and convalescent sera
      • but absence or slight increase in IgM makes the diagnosis difficult
    • Problems with Serology
      • The time between paired acute and convalescent sera
      • Presence of extensive antigenic cross-reactivity
      • Insignificant titers among Immuno compromised patients
      • Patients given blood or blood products : False Positive
    Dr.K.Prasanthi MD
  • 37. Serology
    • Rapid serologic assays such as IgM-capture ELISA (MAC-ELISA) and IgG ELISA can be employed soon after infection.
    • Early in infection, IgM antibody is more specific, while later in infection, IgG antibody is more reactive.
    • Inclusion of monoclonal antibodies (MAbs ) with defined virus specificities in these solid phase assays has allowed for a level of standardization of Molecular amplification techniques
    Dr.K.Prasanthi MD
  • 38. Molecular techniques : PCR
    • Direct impact on rapid response and infectious disease surveillance
    • Essential for the identification of emerging pathogens and for understanding their population structure
    • Useful for characterizing virulence determinants
    • Essential tools for tracking the spread of microbial pathogens
    • May not be possible at district level
      • Identify a nearby lab for doing these tests
    Dr.K.Prasanthi MD
  • 39. Interpretation The essence of reporting
    • Inform the physician of all the positive results
    • If preliminary tests are negative – discuss the diagnostic & therapeutic possibilities with the clinician
    • Discuss with the epidemiologist and veterinarians about the lab data of isolating similar virus from animals and mosquitoes
    • Printed preliminary report should be issued
    • Final report : a legal document ,should be accurate, legible with a definitive identification issued later
    • Reports should be informed immediately to the district health authorities and state health authorities through quick mode of communication
    Dr.K.Prasanthi MD
  • 40. Interpretation The essence of reporting
    • Analyze the locally generated data
    • Interact with other laboratories and epidemiologists
    • Microbiology labs provide an example of effective feedback, achieved by the participation and integration of professionals
    Dr.K.Prasanthi MD
  • 41. Conclusion
    • Infectious disease surveillance requires the active participation of microbiology laboratories, in which new methodologies and robust information technologies should be implemented in order to guarantee early detection of Arboviral outbreaks.
    • Early response strategies should be designed with the cooperation of microbiology laboratories, in which the efforts of clinical and research microbiologists should be coordinated
    Dr.K.Prasanthi MD
  • 42. Integrated Effort Can Work Wonders Dr.Prasanthi. K [email_address] Dr.K.Prasanthi MD