Enhanced Surveillance for Avian Enhanced Surveillance for Avian Influenza and Other Disease Risks Influenza and Other Disease Risks

Professor Roger Morris and colleaguesProfessor Roger Morris and colleaguesMassey University EpiCentreMassey University EpiCentre

Palmerston North Palmerston North New ZealandNew Zealand

Why do surveillance?Why do surveillance?

• To provide evidence that a disease is absentTo provide evidence that a disease is absent• To reduce the risk of taking the wrong To reduce the risk of taking the wrong

disease control actiondisease control action• And the risk of failing to act when necessary And the risk of failing to act when necessary

to do soto do so• We are developing economic methods to We are developing economic methods to

decide how to invest each dollar of decide how to invest each dollar of surveillance money most wiselysurveillance money most wisely

Adapting surveillance to new needsAdapting surveillance to new needs• Surveillance systems have not adapted fast Surveillance systems have not adapted fast

enough to changing requirementsenough to changing requirements• Need to make surveillance more “risk-based”Need to make surveillance more “risk-based”• Diseases form a limited number of Diseases form a limited number of epitypesepitypes – –

require similar surveillance strategiesrequire similar surveillance strategies• ScanningScanning and and targetedtargeted surveillance surveillance• Design better systems to collect and analyse Design better systems to collect and analyse

surveillance data so that it is used effectively for surveillance data so that it is used effectively for making wise decisions making wise decisions

• Make outputs more current and targeted to the Make outputs more current and targeted to the various users of the datavarious users of the data

Risk-based surveillanceRisk-based surveillance

• Develop Develop surveillance portfoliosurveillance portfolio• Balanced combination of techniques Balanced combination of techniques • Scanning surveillanceScanning surveillance – broad assessment – broad assessment• Targeted surveillanceTargeted surveillance – answer specific – answer specific

questions about a diseasequestions about a disease• Use information on risk factors for a disease Use information on risk factors for a disease

to help allocate effort to help allocate effort • Develop Develop risk landscaperisk landscape to guide decisions to guide decisions

on surveillance strategy – surveillance data on surveillance strategy – surveillance data lowers the risk mountains to a flat plainlowers the risk mountains to a flat plain

Surveillance Development Steps

Targeted Surveillance Template

PMStrategyTemplate

Clinical Surveillance

Template

Serological Surveillance

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PM Handling Template

Population Scan Profile

Targeted DiseaseProfile

Surveillance Protection Analysis

Scanning SurveillanceTemplate

On-farmProcedureTemplate

Sampling ProcedureTemplate

The epidemiological toolboxThe epidemiological toolbox

• Data gathering which can yield a Data gathering which can yield a validvalid and and insightfulinsightful assessment of field disease situation assessment of field disease situation

• AnalyticalAnalytical tools which can achieve this tools which can achieve this• ModellingModelling tools to evaluate and predict tools to evaluate and predict• Surveillance portfolioSurveillance portfolio to guide decisions to guide decisions• Integrating information systemIntegrating information system to make it to make it

happenhappen

Disease mapping for survDisease mapping for surveillanceeillance

• GIS software now very important to interpret GIS software now very important to interpret patterns of diseasepatterns of disease

• Especially if used jointly with other Especially if used jointly with other epidemiological methods epidemiological methods

• Allows more cost-effective selection of Allows more cost-effective selection of samples to include in surveillance systemsamples to include in surveillance system

• Now have powerful analytical techniques to Now have powerful analytical techniques to interpret spatial patterns and relate to risk interpret spatial patterns and relate to risk factorsfactors

Prevalence of brucellosis in ArmeniaPrevalence of brucellosis in Armenia

Data gathering methods Data gathering methods • Expanding range of methods usedExpanding range of methods used• Participatory methodsParticipatory methods• Syndromic surveillanceSyndromic surveillance• Field investigation strategies Field investigation strategies • Molecular epidemiology linked with other toolsMolecular epidemiology linked with other tools• Laboratory data should be tightly targetedLaboratory data should be tightly targeted• Integrate laboratory and field methods Integrate laboratory and field methods • Multiple imperfect methods better than single Multiple imperfect methods better than single

perfect sourceperfect source

Participatory Disease SurveillanceParticipatory Disease Surveillance

HPAI detections by PDSHPAI detections by PDS

Terrestrial poultry epidemic curve

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Farmer surveys – simple but effectiveFarmer surveys – simple but effective

300 duck farmers in southern Vietnam interviewed in two weeks

Are ducks really the problem here? – 98% have more than 80% of ducks vaccinated

But 60% of these people have less than 80% of chickens vaccinated

Ducks are not moved nearly as far as senior vets thought

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AI investigation in villages and marketsAI investigation in villages and markets

• Investigating low path viruses as well as H5N1 Investigating low path viruses as well as H5N1 can help give a better understanding of methods can help give a better understanding of methods of spread of AI viruses, and how to control themof spread of AI viruses, and how to control them

• In Hong Kong markets, spread involved drinking In Hong Kong markets, spread involved drinking water, minor poultry species (quail), pet roosterwater, minor poultry species (quail), pet rooster

• Spread of H5N1 to local farms was from Spread of H5N1 to local farms was from markets, not the other waymarkets, not the other way

• Molecular epidemiology showed that there were Molecular epidemiology showed that there were four incursions not one, with different spreadfour incursions not one, with different spread

Studies in VietnamStudies in Vietnam

• Vietnam has had a lot of outbreaks, has made Vietnam has had a lot of outbreaks, has made good progress in reducing the number per yeargood progress in reducing the number per year

• Analysed spatial and temporal pattern of poultry Analysed spatial and temporal pattern of poultry outbreaks 2004-7, especially in two deltasoutbreaks 2004-7, especially in two deltas

• Association between human and poultry casesAssociation between human and poultry cases• Role of ducks and other birds in AI spread, Role of ducks and other birds in AI spread,

factors influencing disease occurrencefactors influencing disease occurrence• Will use this information to develop a targeted Will use this information to develop a targeted

surveillance system, with computer tools to surveillance system, with computer tools to support itsupport it

Poisson regression of risk areasPoisson regression of risk areas

• Examined pattern of outbreaks 2003-4 using a Examined pattern of outbreaks 2003-4 using a grid overlaid on countrygrid overlaid on country

• Areas with over 66% of land irrigated at much Areas with over 66% of land irrigated at much higher risk of outbreakshigher risk of outbreaks

• Areas below 250m altitude at increased riskAreas below 250m altitude at increased risk• Other factors examined were not influentialOther factors examined were not influential• Potential use of satellite imaging to guide Potential use of satellite imaging to guide

surveillance investmentsurveillance investment

Red River deltaRed River delta

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Main vaccination campaigns

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Mekong River deltaMekong River delta

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Main vaccination campaigns

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Spatial SatScan of clusters in RR deltaSpatial SatScan of clusters in RR delta

Spatial autocorrelation in RR deltaSpatial autocorrelation in RR delta

Spatial pattern repeats over yearsSpatial pattern repeats over years

Human and poultry cases in VietnamHuman and poultry cases in Vietnama)b)

Temporal pattern of human and poultry casesTemporal pattern of human and poultry cases

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How should we investigate AI?How should we investigate AI?

• Sero-monitoring has only limited value in a Sero-monitoring has only limited value in a vaccinated populationvaccinated population

• Is NOT a disease surveillance method in this Is NOT a disease surveillance method in this situation, only checks vaccine coveragesituation, only checks vaccine coverage

• Want 80%+ birds protected for AIWant 80%+ birds protected for AI• To test whether protection level adequate, test To test whether protection level adequate, test

250 animals – for any size population250 animals – for any size population• So design sampling plan to test that vaccination So design sampling plan to test that vaccination

program is working in different sectors (3, 4), program is working in different sectors (3, 4), production systems and regions of the countryproduction systems and regions of the country

Disease surveillanceDisease surveillance

• Want to determine distribution of infection and Want to determine distribution of infection and transmission patternstransmission patterns

• PCR is a valuable technique, but only useful if PCR is a valuable technique, but only useful if use virus isolation as well, to confirm that virus is use virus isolation as well, to confirm that virus is circulating and check PCR accuracycirculating and check PCR accuracy

• PCR should always give some positives, even if PCR should always give some positives, even if no infection present!no infection present!

• Virus isolation and molecular strain investigation Virus isolation and molecular strain investigation most useful investigation method to understand most useful investigation method to understand virus transmissionvirus transmission

Investigating AIInvestigating AI

• Focus should be on understanding how infection Focus should be on understanding how infection is transmitted and maintained, then monitoring itis transmitted and maintained, then monitoring it

• Main emphasis should be on investigating sector Main emphasis should be on investigating sector 3 and sector 4 flocks, live bird markets3 and sector 4 flocks, live bird markets

• Need epidemiological investigation strategy to Need epidemiological investigation strategy to answer key questions through good designanswer key questions through good design

• If you ask the right questions, spend far less on If you ask the right questions, spend far less on testing, but get more useful resultstesting, but get more useful results

• Use modern analytical methodsUse modern analytical methods

Data AnalysisData Analysis

• Many powerful analytical methods now availableMany powerful analytical methods now available• Do not need perfect data provided that study Do not need perfect data provided that study

design is sounddesign is sound• Carefully designed intensive epidemiological Carefully designed intensive epidemiological

investigations to examine risk factors are far investigations to examine risk factors are far more useful than large-scale sampling done more useful than large-scale sampling done without collecting risk factor datawithout collecting risk factor data

• Then can use modelling and other techniques to Then can use modelling and other techniques to test various explanations of the disease pattern test various explanations of the disease pattern

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Number of cattle moved OUT of departments for finishing: Jan - Mar

Grey lines indicate movement of > 1000 head for 3-month period. Symbols proportional to number of cattle moved.

Social network analysis can be used to investigate disease spread pathways

Spatial modelling of diseaseSpatial modelling of disease

• Valuable method of assessing possible causesValuable method of assessing possible causes• Valuable for evaluating control optionsValuable for evaluating control options• We use generic spatial models which can be We use generic spatial models which can be

given the “profile” of any known (or new) diseasegiven the “profile” of any known (or new) disease• Modelled foot and mouth disease epidemic in Modelled foot and mouth disease epidemic in

2001 for Britain, modelling avian influenza with 2001 for Britain, modelling avian influenza with same modelsame model

10% High Risk MovementsActual epidemic vs each iteration

Simulation started on 1st June

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Iteration1 - 1787 ips

Iteration2 - 1716 ips

Iteration3 - 1726 ips

Iteration4 - 1717 ips

Iteration5 - 1749 ips

Actual

Monitoring control program resultsMonitoring control program results

• Need baseline data on the situation before Need baseline data on the situation before control activities are startedcontrol activities are started

• Need to use a monitoring system which Need to use a monitoring system which accurately measures change in prevalence of accurately measures change in prevalence of disease and/or infectiondisease and/or infection

• Need to gather information which will allow you Need to gather information which will allow you to detect and respond to weaknesses in the to detect and respond to weaknesses in the programprogram

Brucellosis control in TajikstanBrucellosis control in Tajikstan

Comparison of seroprevalence in 2003 and 2007 in Rasht valley (based on RBT positives)

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Rogun Jirgital Tavildara Nurek Faizobod Tajikabad Rasht Nurabad

Prevalence % in 2003 Prevalence % in 2007

Animal health information systemAnimal health information system

• Use an approach which suits the needs of the Use an approach which suits the needs of the country, start simple but with development plancountry, start simple but with development plan

• It must allow data analysis from the start, and be It must allow data analysis from the start, and be able to advance as the country’s needs changeable to advance as the country’s needs change

• Should include both disease control and Should include both disease control and surveillancesurveillance

• Ability to map disease data should be seen as Ability to map disease data should be seen as an important feature which must be available, an important feature which must be available, though it may not be used at firstthough it may not be used at first

• Retirement planning:Retirement planning:– Invest in multiple assets to spread your riskInvest in multiple assets to spread your risk– Evaluate performance by expected $$ returnEvaluate performance by expected $$ return– Consider variation around $$ returnConsider variation around $$ return

• Surveillance assets:Surveillance assets:Invest in multiple surveillance techniques to give balanced pictureInvest in multiple surveillance techniques to give balanced picture

Can use points per sample or investigation, instead of $$ Can use points per sample or investigation, instead of $$

Each component of surveillance program has a different cost and Each component of surveillance program has a different cost and different number of points achieved by particular test or different number of points achieved by particular test or investigationinvestigation

Applied to BSE and Trichinella, adapting to other diseasesApplied to BSE and Trichinella, adapting to other diseases

Risk-based sampling can give better assurance of disease state Risk-based sampling can give better assurance of disease state

Developing a surveillance portfolio Developing a surveillance portfolio

Comparison of the number of tests allocated per SA and the maximum possible disease prevalence in ewe flocks (α = 0.05) when distributing samples using portfolio theory (PT) and proportional allocation (PA)

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Risk-based sampling for exotic diseaseRisk-based sampling for exotic disease

Risk assessmentRisk assessmentEmerging Infectious Diseases Risk Profile

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Feedback to participantsFeedback to participants

• A major issue in achieving effective surveillance A major issue in achieving effective surveillance is getting cooperation from data providersis getting cooperation from data providers

• Essential for completeness, and to minimise biasEssential for completeness, and to minimise bias• Feedback is most important stimulus to Feedback is most important stimulus to

continuing cooperationcontinuing cooperation

ConclusionConclusion

• We need to be ready to face and solve new We need to be ready to face and solve new disease challengesdisease challenges

• Effective surveillance is the key to quick Effective surveillance is the key to quick detection and effective controldetection and effective control

• Surveillance needs multiple sources of Surveillance needs multiple sources of information, and smart tools for interpretationinformation, and smart tools for interpretation

• Need integrated surveillance and response Need integrated surveillance and response strategy if we are to control future diseases strategy if we are to control future diseases successfully, and a toolbox of techniques to successfully, and a toolbox of techniques to quickly determine what is going onquickly determine what is going on