Issues in syndromic surveillance and influenza preparedness and response

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Issues in syndromic surveillance and influenza
preparedness and response

• A. Tarantola
• 5th Regional Workshop of the SEE Project
• Sofia, Bulgaria
• 27 feb 1 march 2006

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Acknowledgements

• IPH and ALERT Albania
• Isabelle Bonmarin, InVS

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Pandemic risks

• January 2004, Thailand Viet Nam first human
  cases of A(H5N1)
• A(H5N1) virus now endemic in parts of Asia in
  poultry
• The risk of human cases and opportunities for a
  pandemic virus to emerge will continue
• Changes in the ecology of the disease and
  behaviour of the virus have created multiple
  opportunities for a pandemic virus to emerge
• after a reassortment event (genetic material
  exchange between human and avian viruses during
  coinfection of a human being or pig)
• or through a more gradual process of adaptive
  mutation.

Strengthening pandemic influenza preparedness and
response, WHO Report 7 April 2005
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A(H5N1) in birds (as of 27/02/2006)

• 70 countries or territories are affected

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A(H5N1) in humans

• As of 21 Feb 2006
• 170 human cases
• 92 deaths
• In 7 countries
• Exposure to birds
• Clusters
• WHO Phase 3

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WHO phases

• Interpandemic period
• Phase 1 No new influenza virus subtypes have
  been detected in humans.
• Phase 2 ibid., but animal variant threatens
  human disease.
• Pandemic alert period
• Phase 3 Human infection(s) with new subtype but
  no H2H spread.
• Phase 4 Small cluster(s) with limited localized
  H2H transmission
• Phase 5 Larger cluster(s) but H2H spread still
  localized.
• Pandemic period
• Phase 6 Pandemic increased and sustained
  transmission in general population.

WHO global influenza preparedness plan, 2005
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Pandemic risks, vaccines and antivirals

• Vaccines the most important intervention for
  preventing influenza and limiting consequences
  during a pandemic.
• There are three opportunities for using antiviral
  medications
• treat H5N1-infected patients and prevent
  infection in contacts
• to members of community in case of clusters if
  transmissibility ?
• reducing morbidity and mortality during pandemic

Strengthening pandemic influenza preparedness and
response, WHO Report 7 April 2005
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WHO  Countries, prepare! 

• All countries need to undertake preparedness
  activities.
• In affected countries, a high level of vigilance
  for clusters of cases of respiratory disease
  provides an early warning mechanism important for
  all countries.
• Success will depend on several factors, including
  surveillance to provide global early warning of
  human infections with new influenza subtypes.

WHO global influenza preparedness plan, 2005
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Confusion
?

• Early warning (for avian or pandemic influenza
  in humans)

Early warning and response systems
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Influenza surveillance

• Goals detect events indicating unusually large
  or severe outbreaks of influenza as early as
  possible, and to determine the intensity and
  impact of influenza on populations
• At best, influenza surveillance must be
• Stable
• Ongoing
• Representative of populations on the basis of
• Geography
• Demography
• Severity of disease

http//fermat.nap.edu/execsumm_pdf/11150.pdf
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Syndromic surveillance?
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Syndromic surveillance

• Syndromic surveillance is the surveillance of
  disease syndromes (groups of signs and symptoms),
  rather than specific, clinical, or
  laboratory-defined diseases.

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Syndromic surveillance

• Often the only tool at primary level when
  laboratory confirmation is not possible
• Detection of potential outbreaks of targeted
  diseases earlier than with the diagnosis based
  routine surveillance system
• Leads to field investigations for confirmation
  and control.
• IHR
• Implemented in
• Albania
• Serbia

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Avian flu A(H5N1) in humans, Vietnam

• Referral patients
• In 10 pts
• Cough
• Dyspnea
• Polypnea
• High fever
• Digestive signs in 7
• The extent of mildly symptomatic disease in the
  community remains unknown

Hien et al. NEJM 2004 350 (12) 1179
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ALERT Albania

• Use the existing ALERT system?
• Adapt the existing ALERT system?
• Build another function of the surveillance
  system?

?
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Actual structure of the ALERT and 14/Sh
surveillance systems

• ALERT is a syndromic, GP/ER-based EWARS
• 14/Sh is a disease-based system built around ID
  departments

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ALERT items and case definitions
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ALERT Surveillance dataAlbania, 1999-2003
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ALERT Surveillance dataAlbania, 1999-2003
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ALERT Albania

• Usefulness of computers !
• ALERT does not include ID wards (14/Sh)
• Overrepresentation of LRI (why?)
• Cases of VHF were not detected through ALERT
  because based around GPs, not hospitals
• Two successive outbreaks of CCHF in 1999/2000
  were not detected by ALERT at one week.
• Cases were notified by telephone to the district
  epidemiologist within 24 hours.
• Performance of the ALERT system for this syndrome
  was low
• but the PH system performed extremely well.
• ALERT created a fruitful settingfor enhanced
  notification

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ALERT in Serbia

• Outbreak detection
• Increase in cases of ARI meant the influenza
  season could be identified, and a public health
  response triggered
• Individual case detection
• Three cases of VHF reported in the same week
  cluster of hantavirus infection among women
  collecting fruit in a forest.

http//www.eurosurveillance.org/eq/2004/02-04/pdf/
eq_5_2004_24-26.pdf
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Syndromic surveillance and rare events

• Finding true Sars or Avian / Pandemic flu cases
  in the mass of reported ILI syndrome cases is
  like

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Dedicated surveillance systems?
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The French getting ready

• Strengthening of influenza surveillance
• 2 GP surveillance networks
• National Influenza Reference centers
• Surveillance of mortality (influenza, other)
• Surveillance of ER referrals for severe
  repiratory disease (syndromic)
• Epidemiologic intelligence to keep track of
  infected areas
• Detection and investigation of suspected
  imported cases
• and surveillance in animals

Source I. Bonmarin, InVS
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ER visits for influenza, Île de France, 2004-05
season
Source I. Bonmarin, InVS
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Influenza deaths and ILI (Sentinelles), Ile de
France (IDF), 2004-2005 season
Source I. Bonmarin, InVS
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B (VIC) H3N2 H1N1 H1N2
2002/2003
H3N2 H1N1 H1N2 B (YAM)
2003/2004
H3N2 H1N1 B (YAM) B (VIC)
2004/2005
Source I. Bonmarin, InVS
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ER visits/hospital admissions for Influenza
OSCOUR network, 2004-05 season
IDF ER22 N1765
Out of IDF ER12 N620
Source I. Bonmarin, InVS
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Possible imported cases

• Possible cases are investigated if
• Patient with ILI presents ARDS within 7 days of
  returning from a country with A(H5N1) epizootic
• Patient returning from country with epizootic and
  human cases presents acute respiratory disorder
  with fever (gt38) and cough/dyspnea and who had
  within 7 days of symptom onset
• Either an occupational exposure to
• Poultry in a zone with A(H5N1) epizootic
• Animal or human biological samples, presumed or
  proven to be infected
• Animals or humans, presumed or proven to be
  infected
• Or one or more of the following factors
• Prolonged, repeated and close exposure to live or
  dead poultry or their droppings
• Very close and repeated exposure in these zones
  to a confirmed or highly suspected case of H5
  influenza (ARDS or unexplained deaths).

Source I. Bonmarin, InVS
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Source I. Bonmarin, InVS
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Surveillance of potentially imported cases
13/08/04 to 06/02/06
Source I. Bonmarin, InVS
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Discussion
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Surveillance for pandemic preparedness
principles (WHO)

• Integrate disease data with clinical /
  virological data
• Aim
• detect first human cases / H2H transmission
  (phase 3-4)
• detect large clusters/sustained H2H transmission
  (phase 5)
• assess transmission patterns and control efforts
  (phase 6)
• Changing attributes over time
• Pre-pandemic phase
• Early warning
• Most important
• Pandemic phase
• identify priority groups for interventions
• Monitor the burden of disease
• Assess impact on health and other services

http//www.who.int/csr/disease/avian_influenza/fin
al.pdf
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Finding human cases of A/P flu

• Exhaustive (sensitive) esp. pre-pandemic
• Time/cost-effective (specific)
• Rapid
• Leading to specific action

Miss none but dont drown
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Surveillance and A/P influenza

• Syndromic surveillance
• Particularly sensitive
• Useful for early detection of epidemics, not
  cases
• Monitor epidemic trends
• To guide PH decisionmakers
• To adjust resources

• Dedicated system
• Particularly specific
• Useful for detection of all cases and contact
  tracing
• Well-articulated with lab
• Also to detect trends during pandemic

• Also consider Feasability, Costs
• Add specific item for severe respiratory syndrome?

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Surveillance for pandemic preparedness method
(WHO)

• Base system on enhanced hospital-based
  surveillance
• Mobilize communities to report unusual events
  (cluster surveillance)
• Intensive case/cluster investigations
• Well-defined protocols
• If no money, reinforce existing systems to
  detect/investigate clusters of acute febrile and
  severe respiratory disease

http//www.who.int/csr/disease/avian_influenza/fin
al.pdf
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If based solely on EWARS

• Second choice
• Make sure hospitals are included/integrated
• Add a case definition
• Highly sensitive
• Highly specific
• Procedures and protocols
• Add a circuit for virological testing

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• Thank you for your attention
• a.tarantola_at_invs.sante.fr