measuring and monitoring foot and mouth disease occurrence melissa mclaws eufmd

Measuring and Monitoring FMD Occurrence Melissa McLaws EuFMD

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, Animal Health Research Institute, Cairo, Egypt

Soheir Hassan Abdel-Kader, Iman Ali Farag, Amaal Ibrahim Attya Mansour, 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 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?

Incidence (%)6.00 - 12.004.00 - 6.002.00 - 4.001.00 - 2.000.50 - 1.000.00 - 0.50No data

no. villages reporting in 2010 / ttl villages in province

2010 Village Incidence FMD reports

0

100

200

300

num

ber

of re

po

rts

Jan

2009

Apr

200

9

Jul 2

009

Oct 2

009

Jan

2010

Apr

201

0

Jul 2

010

Oct 2

010

month

Turkey:2009-2010

All FMD reports

Monitoring FMD Occurrence: Case Reports

Turkey

2009-2010

2010 Village level incidence

Monitoring FMD Occurrence: Case Reports

• Most are laboratory confirmed & serotyped

0

100

200

300

400

num

ber

of o

utb

reaks

Jan

2001

Jan

2002

Jan

2003

Jan

2004

Jan

2005

Jan

2006

Jan

2007

Jan

2008

Jan

2009

Jan

2010

Jan

2011

Jan

2012

Month

All Outbreaks

05

01

00

150

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of o

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reaks

Jan

2001

Jan

2002

Jan

2003

Jan

2004

Jan

2005

Jan

2006

Jan

2007

Jan

2008

Jan

2009

Jan

2010

Jan

2011

Jan

2012

Month

Serotype A

05

01

00

150

200

250

num

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of o

utb

reaks

Jan

2001

Jan

2002

Jan

2003

Jan

2004

Jan

2005

Jan

2006

Jan

2007

Jan

2008

Jan

2009

Jan

2010

Jan

2011

Jan

2012

Month

Serotype O

05

01

00

150

200

250

num

ber

of o

utb

reaks

Jan

2001

Jan

2002

Jan

2003

Jan

2004

Jan

2005

Jan

2006

Jan

2007

Jan

2008

Jan

2009

Jan

2010

Jan

2011

Jan

2012

Month

Serotype Asia1

O Asia-1 A

Turkey: 2001-2012

Monitoring FMD Occurrence: Active surveillance

• Clinical cases

• NSP serology

– Sampling young stock gives picture of FMD infection in recent months

Incidence80.00 - 100.0060.00 - 80.0040.00 - 60.0020.00 - 40.000.00 - 20.00No data

2010 Village Seroprevalence

Turkey: 2010

• 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

districts, 554 villages

74 provinces, 460

districts, 946 villages

1 province, 14 districts

281 epi-units

-60 samples /village -60 samples /village - 30 samples/epi unit

-cattle only

-mostly 4-18 months

50% cattle, 50% SR

-mostly 4-18 months

-cattle only

-6-24 months

How to relate reporting and serological data?

Incidence6.00 - 12.004.00 - 6.002.00 - 4.001.00 - 2.000.50 - 1.000.00 - 0.50No data

no. villages reporting in 2010/ttl villages in province







2010 2009

Serology

Reports

Incidence (%)6.00 - 12.004.00 - 6.002.00 - 4.001.00 - 2.000.50 - 1.000.00 - 0.50No data

no. villages reporting in 2010 / ttl villages in province


0

100

200

300

num

ber

of re

po

rts

Jan

2009

Apr

200

9

Jul 2

009

Oct 2

009

Jan

2010

Apr

201

0

Jul 2

010

Oct 2

010

month

Turkey:2009-2010

All FMD reports

Relative Incidence200.00 - 500.00100.00 - 200.0080.00 - 100.0060.00 - 80.0040.00 - 60.0020.00 - 40.000.00 - 20.00No data

Serological/Report Village Incidence 2009

Relative comparison (serological ÷ report incidence)

Relative Incidence200.00 - 500.00100.00 - 200.0080.00 - 100.0060.00 - 80.0040.00 - 60.0020.00 - 40.000.00 - 20.00No data

Serological/Report Village Incidence 2010

2009:

Median 30X

2010:

Median 11X

Absolute comparison (Serology minus Report incidence)

Incidence difference (%)80 - 10060 - 8040 - 6020 - 400 - 20-10 - 0No data

Serological and Report Village Incidence 2009: Absolute difference

Incidence difference (%)80 - 10060 - 8040 - 6020 - 400 - 20-10 - 0No data

Serological and Report Village Incidence 2010: Absolute difference

Median difference: 20% Median difference: 29%

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)

Incidence85.71 - 100.0080.71 - 85.7171.43 - 80.7166.67 - 71.4350.00 - 66.67

2011 Incidence FMD serosurvey

Incidence28.57 - 40.0027.27 - 28.5719.81 - 27.2716.67 - 19.818.57 - 16.670.00 - 8.57

Incidence FMD reports (sample)

Incidence13.77 - 32.769.97 - 13.779.18 - 9.977.81 - 9.187.37 - 7.811.52 - 7.37

16 mo prior to survey

Incidence FMD reports

District-level FMD Incidence:

Serosurvey Clinical signs: Survey Clinical signs: Offical reports

No significant correlation (Spearman’s)


Epi-unit level Turkey

2009

Turkey

2010

W. AZB

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%

50

60

70

80

90

100

se

rolo

gic

al in

cid

en

ce

0.00 10.00 20.00 30.00 40.00report incidence

W. Azerbaijan serosurvey

02

04

06

08

01

00

se

rolo

gic

al in

cid

en

ce

0 5 10 15report incidence

Turkey 2010

Differences: Serological and Report data

May 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 data

May 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

Egypt • Nationwide serosurvey in 2011

– 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

0

50

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350

0

10

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30

40

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70

80

Nile delta

Central Upper East West Total n

um

ber

villa

ges

sam

ple

d

% p

osit

ive

Egypt 2011: Large ruminant results in serosurvey

% 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

SEROPREVALENCE

VILLAGE

LEVEL

2009 2010 2009 2010

<4 mo 16.67%

(0-49%)

- 20% 33%

4-12

mo

8.9%

(8.4-9.3%)

12.9

(12.5-13.2)

13-18

mo

9.1%

(8.4-9.7%)

15.4

(14.9-15.9)

19-24

mo

19.1% (18.0-

20.1%)

17.3

(16.3-18.2)

>24 mo 16%

(2.8-28.4%)

21.3

(18.0-24.5) 0

100

200

300

num

ber

of re

po

rts

Jan

2009

Apr

200

9

Jul 2

009

Oct 2

009

Jan

2010

Apr

201

0

Jul 2

010

Oct 2

010

month

Turkey:2009-2010

All FMD reports

Serosurveys

0

100

200

300

400

num

ber

of o

utb

reaks

Jan

2001

Jan

2002

Jan

2003

Jan

2004

Jan

2005

Jan

2006

Jan

2007

Jan

2008

Jan

2009

Jan

2010

Jan

2011

Jan

2012

Month

All Outbreaks

measuring and monitoring foot and mouth disease occurrence melissa mclaws eufmd

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