Transcript Detection and Response to Infectious Disease Outbreaks

Detection and Response to Infectious
Disease Outbreaks
H5N1 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
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the beginning of a potential pandemic
Overview of the Steps of a
Case Investigation
 Pre-Investigation
 Planning the Response
 Investigation
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Case definitions
Specimen collection
Case finding
Interviewing
Contact identification
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Data collection
Data management
Data analysis
Assessing transmission
Reporting
Writing a summary report
 Post-Investigation
 Evaluate performance
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When to Initiate Investigations?
Cases of severe acute respiratory
infection with a possible link to AI
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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:
Mounts,
Photo:Tony
Tony Mounts,
CDCCDC
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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-Investigation:
Plan the Response
• Convene rapid response team (RRT)
• Possible roles and
responsibilities
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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:
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Close contact (within 1 meter) with a person who is a
suspected, probable, or confirmed H5N1 case;
– caring for, speaking with, or touching
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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)
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Consumption of raw or undercooked poultry products
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Close contact with a confirmed H5N1 infected animal other
than poultry or wild birds
– e.g. cat, dog, or pig
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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
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respiratory illness
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 hotlines
Public 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/guidelines/pharmamanagement/en/index.html
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Why Use Risk Stratification?
• Helps prioritize limited human and nonhuman resources
• Provides a rational a priori
explanation for who will, and will not,
receive limited resources.
• Is used in the World Health
organization’s 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
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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
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Animal health: implementation of culling,
disinfection, surveillance, poultry
vaccination
Infection control
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Treatment of ill patients
Contact tracing
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Isolation of suspected and confirmed cases
PPE, proper infection control precautions
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?
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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
Reduce spread within
national/local populations
Travel screening and
entry/exit restrictions
Social distancing;
quarantine of exposed;
isolation
Personal protective
measures (e.g., masks)
Public health
communication campaign
Reduce an individual
person's risk
Communicate risk to the
public
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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
#1
#2
Daily
Cases
Pandemic outbreak
With intervention
#3
Days since First Case
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