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

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 province2010 Village Incidence FMD reports

010

020

030

0nu

mbe

r of r

epor

ts

Jan 2

009

Apr 20

09

Jul 2

009

Oct 20

09

Jan 2

010

Apr 20

10

Jul 2

010

Oct 20

10

month

Turkey:2009-2010All FMD reports

Monitoring FMD Occurrence: Passive Surveillance

Turkey Case Reports

2009-2010

2010 Village level incidence

Monitoring FMD Occurrence: Case Reports

• Most are laboratory confirmed & serotyped

010

020

030

040

0nu

mbe

r of o

utbr

eaks

Jan 2

001

Jan 2

002

Jan 2

003

Jan 2

004

Jan 2

005

Jan 2

006

Jan 2

007

Jan 2

008

Jan 2

009

Jan 2

010

Jan 2

011

Jan 2

012

Month

All Outbreaks

050

100

150

200

250

num

ber o

f out

brea

ks

Jan 2

001

Jan 2

002

Jan 2

003

Jan 2

004

Jan 2

005

Jan 2

006

Jan 2

007

Jan 2

008

Jan 2

009

Jan 2

010

Jan 2

011

Jan 2

012

Month

Serotype A

050

100

150

200

250

num

ber o

f out

brea

ks

Jan 2

001

Jan 2

002

Jan 2

003

Jan 2

004

Jan 2

005

Jan 2

006

Jan 2

007

Jan 2

008

Jan 2

009

Jan 2

010

Jan 2

011

Jan 2

012

Month

Serotype O

050

100

150

200

250

num

ber o

f out

brea

ks

Jan 2

001

Jan 2

002

Jan 2

003

Jan 2

004

Jan 2

005

Jan 2

006

Jan 2

007

Jan 2

008

Jan 2

009

Jan 2

010

Jan 2

011

Jan 2

012

Month

Serotype Asia1O 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 province2009 Village Incidence FMD reports

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

2009 Village Seroprevalence

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

2010 Village Seroprevalence

How to relate reporting and serological data? 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 province2010 Village Incidence FMD reports

010

020

030

0nu

mbe

r of r

epor

ts

Jan 2

009

Apr 20

09

Jul 2

009

Oct 20

09

Jan 2

010

Apr 20

10

Jul 2

010

Oct 20

10

month

Turkey:2009-2010All 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 surveyIncidence FMD reports

District-level FMD Incidence:

Serosurvey Clinical signs: Survey Clinical signs: Offical reports

No significant correlation (Spearman’s)

How to relate reporting and serological data? 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%

5060

7080

9010

0se

rolo

gica

l inc

iden

ce

0.00 10.00 20.00 30.00 40.00report incidence

W. Azerbaijan serosurvey

020

4060

8010

0se

rolo

gica

l inc

iden

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

100

150

200

250

300

350

0

10

20

30

40

50

60

70

80

Niledelta

Central Upper East West Totalnu

mbe

r vill

ages

sam

pled

% p

ositi

ve

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