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Measuring and Monitoring Foot and Mouth Disease Occurrence Melissa McLaws EuFMD
 

Measuring and Monitoring Foot and Mouth Disease Occurrence Melissa McLaws EuFMD

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Monitoring FMD is key principle of PCP ...

Monitoring FMD is key principle of PCP
Measuring FMD occurrence to:
1. Assess FMD risk
– Within country:
oSpecies, sector, husbandry system, area
oTo target control and inform FMD impact
assessment
2. Monitor changes over time
– Detect ‘events’ (epidemics)
– Efficacy of control strategy
But what is the best way to do it?

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    Measuring and Monitoring Foot and Mouth Disease Occurrence Melissa McLaws EuFMD Measuring and Monitoring Foot and Mouth Disease Occurrence Melissa McLaws EuFMD Presentation Transcript

    • Measuring and MonitoringFMD OccurrenceMelissa McLawsEuFMD
    • Acknowledgements•Chris Bartels: EuFMD•Naci Bulut: FMD Institute, Ankara, Turkey•Theo Knight Jones: Institute for Animal Health, Pirbright, UK•Shams Amin Abo Gabal, Rehab Abdel-Kader El Bassal, AnimalHealth Research Institute, Cairo, Egypt Soheir Hassan Abdel-Kader, Iman Ali Farag, Amaal Ibrahim AttyaMansour, General Organization for Veterinary Services, Cairo,Egypt•General Directorate for Food and Control, Ankara, Turkey•Iranian Veterinary Organization, Tehran, Iran
    • Key points• Data from Turkey and Iran show: – Yearly incidence rate 10-30 X higher when measured using NSP serosurveys compared to reports of suspected cases – Provincial (or district) level FMD incidence measured by 1) reports and 2) serological data were poorly correlated• FMD reporting should be encouraged and reports analysed continuously (monthly) to detect ‘events’• Carefully designed serosurveys should be conducted regularly (annually if possible) – Unbiased measure of FMD infection, best information about risk factors
    • Monitoring FMD is key principle of PCPMeasuring FMD occurrence to:1. Assess FMD risk – Within country: o Species, sector, husbandry system, area o To target control and inform FMD impact assessment2. Monitor changes over time – Detect ‘events’ (epidemics) – Efficacy of control strategyBut what is the best way to do it?
    • Monitoring FMD Occurrence: Case Reports 2009-2010 All FMD reports Turkey Turkey:2009-2010 300 number of reports 200 1002010 Village level incidence 0 9 09 0 10 9 0 09 10 00 01 00 01 20 20 20 20 r2 r2 l2 l2 ct ct n n Ju Ju Ap Ap Ja Ja O O 2010 Village Incidence FMD reports month no. villages reporting in 2010 / ttl villages in province Incidence (%) 6.00 - 12.00 4.00 - 6.00 2.00 - 4.00 1.00 - 2.00 0.50 - 1.00 0.00 - 0.50 No data
    • Ja 100 150 200 250 n 50 20 0 100 200 300 400 01 Ja Ja n n 0 20 20 02 Ja 01 n Ja 20 O Ja 03 n n 20 20 02 04 Ja Ja n n 20 05 20 Ja n 03 20 Ja 06 Ja n n 20 20 07 04 JaMonth n Ja 20 n Serotype O 08 Ja n 20 20 05 Turkey: 2001-2012 09 Ja Ja n n 20 10 20 Ja n 06 20 Ja 11 n Ja n 20 20 12 07 number of outbreaks Ja Month n 20 08 All Outbreaks Ja n 20 09 Ja 100 150 200 250 n Ja 50 n 20 20 0 10 01 Ja Ja n n 20 02 20 Ja n 11 A 20 Ja 03 Ja n n 20 20 04 12 Ja n 20 05 Ja n 20 06 Ja n 20 07 JaMonth n 20 Serotype A 08 Ja n 20 09 Ja n 20 10 Ja n 20 11 Ja n 20 12 number of outbreaks Ja 100 150 200 250 n 50 20 0 01 Ja n 20 02 Ja n 20 03 Ja n 20 04 Ja n 20 Asia-1 05 Ja n 20 06 Ja n 20 07 JaMonth n 20 08 Ja n Serotype Asia1 20 09 Ja n 20 10 Ja n 20 11 • Most are laboratory Ja n 20 Monitoring FMD Occurrence: Case Reports 12 confirmed & serotyped
    • Monitoring FMD Occurrence: Active surveillance• Clinical cases• NSP serology – Sampling young stock gives picture of FMD infection in recent months 2010 Village Seroprevalence Incidence 80.00 - 100.00 60.00 - 80.00 40.00 - 60.00 20.00 - 40.00 0.00 - 20.00 No data Turkey: 2010
    • How to relate reporting and serological data?• Compare FMD incidence measured using survey data and reports in Turkey and Iran • Well developed passive reporting systems • Extensive serosurveys Turkey (spring 2009) Turkey (spring 2010) W. Azerbaijan, June 2011 -32,670 samples -64,765 samples -8349 samples 78 provinces, 334 74 provinces, 460 1 province, 14 districts districts, 554 villages districts, 946 villages 281 epi-units -60 samples /village -60 samples /village - 30 samples/epi unit -cattle only 50% cattle, 50% SR -cattle only -mostly 4-18 months -mostly 4-18 months -6-24 months
    • How to relate reporting and serological data? 2009 2010Serology 2009 Village Seroprevalence 2010 Village Seroprevalence Incidence Incidence 80.00 - 100.00 80.00 - 100.00 60.00 - 80.00 60.00 - 80.00 40.00 - 60.00 40.00 - 60.00 20.00 - 40.00 20.00 - 40.00 0.00 - 20.00 0.00 - 20.00 No data No dataReports 2010 Village Incidence FMD reports no. villages reporting in 2010 / ttl villages in province 2009 Village Incidence FMD reports no. villages reporting in 2010/ttl villages in province Incidence (%) 6.00 - 12.00 4.00 - 6.00 2.00 - 4.00 Incidence 1.00 - 2.00 6.00 - 12.00 0.50 - 1.00 4.00 - 6.00 0.00 - 0.50 2.00 - 4.00 No data 1.00 - 2.00 0.50 - 1.00 0.00 - 0.50 No data All FMD reports Turkey:2009-2010 300 number of reports 200 100 0 9 09 0 10 09 9 10 0 00 01 00 01 20 20 20 20 r2 r2 l2 l2 ct ct n n Ju Ju Ap Ap Ja Ja O O month
    • Relative comparison(serological ÷ report incidence) Serological/Report Village Incidence 2009 Relative Incidence 200.00 - 500.00 100.00 - 200.00 80.00 - 100.00 2009: 60.00 - 80.00 40.00 - 60.00 20.00 - 40.00 Median 30X 0.00 - 20.00 No data Serological/Report Village Incidence 2010 Relative Incidence 200.00 - 500.00 100.00 - 200.00 80.00 - 100.00 2010: 60.00 - 80.00 40.00 - 60.00 20.00 - 40.00 Median 11X 0.00 - 20.00 No data
    • Absolute comparison (Serology minus Report incidence) Serological and Report Village Incidence 2009: Absolute difference Incidence difference (%) Median 80 - 100 60 - 80 40 - 60 20 - 40 0 - 20 difference: 20% -10 - 0 No dataSerological and Report Village Incidence 2010: Absolute difference Incidence difference (%) 80 - 100 60 - 80 40 - 60 Median 20 - 40 0 - 20 difference: 29% -10 - 0 No data
    • W. Azerbaijan serosurvey• 80.2% of epi-units had at least 5 calves with a high titre (>70% inhibition)• 18% observed clinical signs in their stock in the previous 12 months (questionnaire) District-level FMD Incidence: Serosurvey Clinical signs: Survey Clinical signs: Offical reports 2011 Incidence FMD serosurvey Incidence FMD reports (sample) Incidence FMD reports 16 mo prior to survey Incidence Incidence 85.71 - 100.00 28.57 - 40.00 Incidence 80.71 - 85.71 27.27 - 28.57 13.77 - 32.76 19.81 - 27.27 9.97 - 13.77 71.43 - 80.71 9.18 - 9.97 66.67 - 71.43 16.67 - 19.81 8.57 - 16.67 7.81 - 9.18 50.00 - 66.67 7.37 - 7.81 0.00 - 8.57 1.52 - 7.37
    • How to relate reporting and serological data?Epi-unit level Turkey Turkey W. AZB 2009 2010 Median serological incidence 20% 33% 81% GISVet survey Median report incidence 0.22% 2.8% 9% 20% Median relative incidence 30.8 11.8 8.2 3.7 Median incidence difference 20% 29% 69% 65% Turkey 2010 W. Azerbaijan serosurvey 100 100 No significant 90 80 serological incidence serological incidence correlation 80 60 70 40 (Spearman’s) 60 20 50 0 0 5 10 15 0.00 10.00 20.00 30.00 40.00 report incidence report incidence
    • Differences: Serological and Report dataMay be due to: 1. Under-reporting 2. Subclinical infection • FMD signs observed by farmers on: – 17% NSP+ epi-units in W. Azerbaijan – 41% NSP+ calves (0-12 months) in Asia-1 outbreak investigation in Turkey – 86% NSP+ calves (0-12 months) in Asia-1 outbreak investigation in Turkey • Will vary by FMD strain, species infected, vaccination status
    • Differences: Serological and Report dataMay be due to: 3. NSP antibody induced by vaccine rather than infection • Especially if use unpurified vaccine • Less likely if youngstock targeted in survey (?) 4. Reflection of previous year’s cases? • Compared Turkish serosurvey results to previous year’s reports and correlation not improved
    • Both approaches contribute to assessing and monitoring FMD risk• Reports of suspect clinical cases – Essential for early detection & response (PCP Stage 3 and higher) – Real-time, linked to control – Laboratory confirmation including serotype – Cost-effective – Effectiveness dependent on favourable ‘attitude’ to reporting – Subject to bias, under-reporting
    • • Nationwide serosurvey in 2011Egypt – 5299 ruminant samples tested in 310 villages • NSP-Ab positive: – 17.6% samples (95%CI: 16.6 – 18.6%) – 78% villages (95% CI: 73-82%) • 2011: 15 reports of suspect disease Egypt 2011: Large ruminant results in serosurvey 80 350 number villages sampled 70 300 60 250% positive 50 200 40 150 30 20 100 10 50 0 0 Nile Central Upper East West Total delta % villages with >=2 seropositive % cattle % buffalo Nr villages tested
    • Both approaches contribute to assessing and monitoring FMD risk• NSP serology – Detects clinical and subclinical FMD (ie measures FMD infection) – Less biased (with careful design!) • Unit of analysis: what is a ‘case’? • Target young stock – Combine with questionnaire about risk factors – Resource intensive • Survey can be combined with post-vaccination monitoring (SP serosurvey)
    • Key points• Data from Turkey and Iran show: – Yearly incidence rate 10-30 X higher when measured using NSP serosurveys compared to reports of suspected cases – Provincial (or district) level FMD incidence measured by 1) reports and 2) serological data were poorly correlated• FMD reporting should be encouraged and reports analysed continuously (monthly) to detect ‘events’• Carefully designed serosurveys should be conducted regularly (annually if possible) – Unbiased measure of FMD infection, best information about risk factors
    • Thank you!•EuFMD•FMD Institute, Ankara, Turkey•Institute for Animal Health, Pirbright, UK•Animal Health Research Institute, Cairo, Egypt•General Organization for Veterinary Services, Cairo, Egypt•General Directorate for Food and Control, Ankara, Turkey•Iranian Veterinary Organization, Tehran, Iran
    • 2010 epidemic in Turkey: Use of reports to detect surge in cases ANIMAL LEVEL VILLAGE SEROPREVALENCE LEVEL Serosurveys 2009 2010 2009 2010<4 mo 16.67% - 20% 33% (0-49%)4-12 8.9% 12.9 All FMD reportsmo (8.4-9.3%) (12.5-13.2) Turkey:2009-2010 30013-18 9.1% 15.4mo (8.4-9.7%) (14.9-15.9) number of reports 20019-24 19.1% (18.0- 17.3mo 20.1%) (16.3-18.2) 100>24 mo 16% 21.3 (2.8-28.4%) (18.0-24.5) 0 9 09 0 10 9 0 09 10 00 01 00 01 20 20 20 20 r2 r2 l2 l2 ct ct n n Ju Ju Ap Ap Ja Ja O O month