Detection and Response to Infectious Disease Outbreaks H5N1 as a case-study

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Detection and Response to Infectious Disease
OutbreaksH5N1 as a case-study

• Daniel S. Miller MD, MPH
• International Influenza Unit
• U.S. Department of Health
• Human Services

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Detection

• Requires timely and quality information to be
  collected at local levels by trained personnel
  about possible occurrence of severe acute
  respiratory illness
• Requires rapid reporting to a more central
  authority for epidemiologic assessment,
  investigation, and possible response by
  specifically trained personnel
• Requires adequate laboratory capabilities to
  identify or confirm H5N1

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Case Investigation Objectives

• Confirm or exclude H5N1 virus infection
• Reduce morbidity and mortality through rapid
  identification, isolation, treatment, clinical
  management of cases and follow-up of contacts
• Reduce further spread of H5N1 virus infection
  through identification of exposure sources and
  implementation of control measures
• Determine if cases or cluster of cases represent
  the beginning of a potential pandemic

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Overview of the Steps of a Case Investigation

• Pre-Investigation
• Planning the Response
• Investigation
• Case definitions
• Specimen collection
• Case finding
• Interviewing
• Contact identification
• Post-Investigation
• Evaluate performance

• Data collection
• Data management
• Data analysis
• Assessing transmission
• Reporting
• Writing a summary report

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When to Initiate Investigations?

• Cases of severe acute respiratory infection with
  a possible link to AI
• Any case meeting WHO suspect, probable or
  confirmed case definition.
• SARI cases in workers in poultry industry
• Association with sick or dying poultry or wild
  birds
• History of travel within the last 10 days to an
  area or region known to have circulating avian
  influenza

Photo Tony Mounts, CDC
Photo Tony Mounts, CDC
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Triggers without H5N1 Link

• Cases in Health Care Workers who care for
  patients with SARI or pneumonia
• Clusters of 2 or more SARI cases in a 2 week
  period
• 2 people in a family
• Cases in a small geographic area
• Cases with social or occupational connection
• Increases in cases at a hospital compared
  to the same time in previous years
• Change in the epidemiology of cases

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Other Triggers for Investigation

• Poultry events excessive deaths
• Rumors from informal data sources
• news media
• information hotlines

Photo Diane Gross, CDC
Photo Diane Gross, CDC
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Pre-InvestigationPlan the Response

• Convene rapid response team (RRT)
• Possible roles and responsibilities
• Team leader
• Epidemiologists
• Medical officer
• Veterinary officer
• Laboratory scientist
• Communications specialist
• Logistician
• Data Manager

Photo Tim Uyeki, CDC
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An important resource for H5N1 case
investigations
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WHO Suspected Case Exposures

• Close contact (within 1 meter) with a person who
  is a suspected, probable, or confirmed H5N1 case
• caring for, speaking with, or touching
• Exposure to poultry or wild birds or their
  remains or to environments contaminated by their
  feces in an area where H5N1 infections in
  animals/humans have been suspected/confirmed in
  the last month
• handling, slaughtering, defeathering, butchering,
  preparation for consumption)
• Consumption of raw or undercooked poultry
  products
• Close contact with a confirmed H5N1 infected
  animal other than poultry or wild birds
• e.g. cat, dog, or pig
• Handling samples (animal or human) suspected of
  containing H5N1 virus in a laboratory or other
  setting.

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Why is Case Finding Important?

• Identify all possible cases in a community
• Treat affected persons, determine exposure
  sources, and prevent further transmission
• May provide information about potential
  human-to-human transmission
• Obtain information on cases related in time and
  location to other cases or clusters

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Active Case Finding

• Attempt to identify additional cases beyond known
  cases and close contacts
• Persons who may have been exposed to the same
  H5N1 source as the case
• Persons with bird/animal exposures or healthcare
  workers caring for H5N1 patients
• Persons with unexplained acute lower respiratory
  infection with fever or persons who died of an
  unexplained acute respiratory illness

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How to Find Cases

• Active case finding
• Refer/obtain respiratory specimens for H5N1
  testing from suspected cases
• Refer suspect cases for medical care
• Cases should be sought in the area where a case
  has occurred
• Consider house-to-house searches, visits to
  health care facilities, private practitioners,
  traditional healers, laboratories

Photo Diane Gross, CDC
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How to Find Cases

• Passive case finding
• Routine surveillance
• Rumor hotlinesPublic information messages in the
  affected communities
• Can be enhanced with refresher trainings etc

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Enhanced Surveillance

• Enhance routine surveillance in areas where H5N1
  cases live or where animal outbreaks are
  occurring
• Consider active surveillance in hospital
  in-patient units and emergency rooms traditional
  healers, private practitioners, private
  laboratories active surveillance of health care
  workers, persons exposed to birds/animals
• Duration of enhanced surveillance is a minimum of
  2 weeks after the last human H5N1 case is
  identified (2 incubation periods)
• Enhanced surveillance may need to be maintained
  for longer periods if H5N1 poultry outbreaks are
  not controlled

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What is Contact Tracing?

• The identification and diagnosis of persons who
  may have been in close contact with an infected
  individual during the infectious period

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Risk Stratification Based on Exposures

• High risk exposure
• (e.g. household or close family contacts)
• Moderate risk exposure
• (e.g. other exposed persons who were not wearing
  appropriate PPE)
• Low risk exposure
• (e.g. unexposed persons or those wearing
  appropriate PPE)
• WHO Rapid Advice Guidelines on pharmacological
  management of humans infected with avian
  influenza A (H5N1) virus
• http//www.who.int/csr/disease/avian_influenza/gui
  delines/pharmamanagement/en/index.html

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Why Use Risk Stratification?

• Helps prioritize limited human and non-human
  resources
• Provides a rational a priori explanation for who
  will, and will not, receive limited resources.
• Is used in the World Health organizations
  recommendations on post-exposure antiviral
  chemoprophylaxis

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Monitoring and Managing Contacts

• Actively monitor (daily) contacts for signs of
  illness for 7 days after exposure to a case or to
  infected birds
• Encourage self-health monitoring
• Instruct to report onset of symptoms
• Visit or phone daily to monitor for illness
• Refer contacts with fever and respiratory illness
  to medical care, isolation, treatment obtain
  respiratory specimens for H5N1 testing
• Request voluntary home quarantine of all contacts
  for 7 days post exposure
• Consider antiviral chemoprophylaxis, if available

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Prioritize Contact Identification

• If number of contacts is large, focus on
• Contacts of probable and laboratory confirmed
  H5N1 cases
• Contacts with prolonged close exposures to a
  suspected H5N1 case (e.g. household contacts
  sharing the same sleeping and eating space,
  persons providing bedside care)

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Inform Those who Need to Know

• Local Level who is responsible for submitting
  H5N1 case reports? When should this be done?
• National Level who needs to be updated on the
  progress of the investigation and receive the
  final report on number of H5N1 cases? Who is
  responsible for assuring that this occurs?
• International Level Probable, and confirmed H5N1
  cases should be reported immediately to WHO. The
  Ministry of Health will be responsible for
  notifying WHO.

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Prevention and Control Activities

• Animal health implementation of culling,
  disinfection, surveillance, poultry vaccination
• Infection control
• Isolation of suspected and confirmed cases
• PPE, proper infection control precautions
• Treatment of ill patients
• Contact tracing
• Antiviral chemoprophylaxis of high-risk groups
• Active surveillance of contacts for illness
• Voluntary quarantine of well contacts
• Implementation of active surveillance and
  enhanced case finding

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Why communicate the findings?

• A document for action
• Control and prevention measures
• To share new insights
• To obtain national and international resources
• Documents the investigation
• To assist other nations districts or countries
  with investigation
• Inform the public
• Prevents future outbreaks

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Infection Control Measures

• All interventions should be used in combination
  with infection control measures including
• Hand hygiene
• Cough etiquette
• Environmental cleaning
• Personal protective equipment such as face masks

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What are NPIs?

• Non-pharmaceutical interventions (NPIs)
• Measures other than vaccines and antivirals that
  may reduce the risk of transmission of influenza
  to individuals and communities
• NPIs can be implemented at borders, or at the
  level of the community and the individual

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Examples of NPIs
Purpose Potential NPI
Limit spread across borders Travel screening and entry/exit restrictions
Reduce spread within national/local populations Social distancing quarantine of exposed isolation
Reduce an individual person's risk Personal protective measures (e.g., masks)
Communicate risk to the public Public health communication campaign
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Other Definitions I

• Isolation
• Separation or restriction of movement of persons
  ill with an infectious disease in order to
  prevent transmission to others
• Quarantine
• Restriction of persons who are not ill but
  presumed exposed, usually in the home or a
  designated facility
• Social Distancing
• Measures to increase the space between people and
  decrease the frequency of contact among people

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Other Definitions II

• Infection Control
• Hygiene and personal measures to reduce the risk
  of transmission of an infectious agent from an
  infected person to uninfected persons
• Containment
• Efforts undertaken to confine early cases of
  pandemic influenza to a geographic area or
  population
• Mitigation
• Efforts undertake to lessen the impact of
  pandemic influenza on the community
• Cluster
• A laboratory confirmed index case and at least
  one laboratory confirmed epidemiologically-linked
  case

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Why are NPIs being considered?

• During the first few months after a pandemic
  begins
• Vaccine made from a pandemic strain will probably
  not to be available
• Antivirals may be insufficient in quantity,
  ineffective and/or difficult to distribute in a
  timely way
• In many countries of the world, it may be some
  time before either vaccine or antivirals are
  available in sufficient quantity

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What are the Goals of Community-based NPIs?
1. Delay disease transmission and outbreak
peak 2. Decompress peak burden on healthcare
infrastructure 3. Diminish overall cases and
health impacts
Pandemic outbreak with no intervention
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2
Daily Cases
Pandemic outbreak With intervention
3
Days since First Case