Foot and Mouth Disese control strategies

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FOOT-AND-MOUTH DISEASE

IMPLEMENTING EFFECTIVE DISEASE CONTROL PROGRAMS AND ROLE OF NSP ANTIBODY TESTING

V I Bishor & Faisal Siyavudeenubio Biotechnology Systems Pvt. Ltd

Biotechnology Incubation center, Kinfra Hitech Park, Kalamassery, Kochi


Proportions of FMD Virus Serotypes Isolated by the

WRLFMD

64%

7%

23%

4% 2%O

A

C

SAT1

SAT2

SAT3

ASIA1

(n=311)


Foot and Mouth Disease Control in Kerala

• Kerala’s Animal Disease Control Project (ADCP) is lauded as the model for the entire country.

• The vaccination program of ADCP has led to significant reduction in the occurrence of FMD in the state.

• Continuous monitoring and re vaccinations have kept the disease away ‑from the state for years altogether.

• Recent our breaks : factors – Increased movement of slaughter animals into the state – Introduction of new dairy animals from infected areas into the state,– Lack of continuous disease monitoring among livestock populations in the

state that slows down outbreak detection, emergency response and epidemic prevention.

The FMD control program has to be refined by incorporating control measures that consider these new factors, so that we sustain and improve the FMD disease status across the state.


FMD Disease control in Kerala: Proposed measures.

1. Clinical Surveillance2. Migration Control and Monitoring3. Control of cross-border livestock trade4. Early detection measures and epidemic control


Clinical surveillance

1. Regular random sampling of serum from across the state

2. Testing the sample for the presence of infection3. Identification of infected carriers or new

infections4. Quarantine and control measures including

emergency vaccination


Migration Control and Monitoring

• Purchase of new livestock animals under various schemes from other states – While this is a welcome development from a

demographical point of view, it has a serious negative impact on disease control programs.

– Most areas adjoining our state have higher incidence of FMD with less developed disease control systems, there is a high chance that FMD carriers may be imported through inter-state purchase of new dairy animals.

• A program where every new dairy animal imported into the state under government schemes has to be tested and certified free of FMD before the purchase is made has to be considered.


Control of Cross-Border livestock trade.

• Slaughter animals imported into the state through our border check-posts is huge.

• spend just a few hours in the state before they are slaughtered: so risk of infections from these animals lesser in a general sense.

• However, this does not hold for FMD, as the disease is so contagious that even animals that live near the road through which infected animals are transported are at risk of infection.

• A screening program at border check-posts to screen and exclude infected animals has to be implemented

• Ideally, every animal should be checked for infection and the physical or financial responsibility to dispose of the infected animal should be fixed on the importer.

• The tagging system at the check-posts should be extended to retain test data and associate it with individual animals.

• A good vigilance program that randomly screens animals at slaughter-houses can then ensure accountability and assure efficacy of the screening program by cross-checking results from the check-post.


Early detection measures and epidemic control

• The most important step in FMD epidemic control is to quickly establish an infection perimeter.

• All susceptible animals in infected and adjoining areas and areas with high risk of contagion be screened to identify early infections whenever an epidemic is reported.

• This data should be used to establish the infection perimeter quickly and accurately.

• This perimeter should then be used to implement quarantine measures in the infected area, and emergency vaccination should be performed around the perimeter to block spread, as is done today.

• Once the epidemic is over, all the animals in the area should be screened again for the presence of carriers so that follow-up outbreaks do not occur.


FMD control measures: Implementation Challenges.

• A clinical surveillance scheme that aims to detect silent FMD carriers cannot rely on clinical examination, and would require laboratory diagnosis.

– Laboratory facility is limited .– Difficulty in sample management: need additional infrastructure and manpower

• Migration control and monitoring programs that require ‘FMD-free’ certification of dairy animals before purchase would need a testing method, which would allow the veterinary doctor to test the animal at the point of purchase.

• Similar challenges also exist for check-post screening. – A typical animal carriage vehicle will spend 30-45 minutes at the check-post for animal

tagging and clearance. It is impossible to screen all the animals in the carriage within this time using conventional methods. Serum collection and off-site lab diagnosis is not an option here, as infected animals would have carried the infection into the state by the time the results are available.

• In the case of disease screening to establish infection perimeters, quick results are very important

• In all these measures, it is important to make sure that vaccinated, non-infected animals


Rapid FMD NSP Testing

All the FMD control measures outlined above involve fast, reliable, de-centralized screening of the disease.

Requirements for the ideal diagnostic technique

– Quick results should available in just a few minutes.– Should require no instrumentation, instruments should be portable if present.– Should be easy to use.– Should allow decentralized implementation (should not require serum transport)– Should require no, or low, capital expenditure.– Should be able to execute the test and read result in the field itself.– Should not require refrigerated storage.– Should differentiate between vaccinated and infected animals.

The only diagnostic technique available today that satisfies these requirements for FMD diagnosis is the FMD Non-structural-protein (NSP) rapid lateral flow assay.


Practical issues of NSP testing

•The 3ABC polyprotein is concluded to be the single most reliable indicator of infection (Concerted Action CT93 0909, 1998).

•The 3ABC protein is not serotype specific. A positive result of NSP test indicates an infection with the FMD virus, irrespective of the serotype.

• This not contain any infectious material and therefore does not, contrary to a VN test, have to be performed in high containment.

• In case of an outbreak large numbers of samples can be processed in the field.

• Waiting time for the test is minimal, since the test provides results within minutes.

• the test is tested and validated in local cattle .

• The NSP marker-test is recommended for herd diagnosis rather than for individual diagnosis.


EU FMD Committee Recommendation

• Using conventional diagnostic techniques – Not possible to distinguish FMD infected animals from purely vaccinated

animals– In vaccinated areas, have limited possibilities to monitor virus presence or

circulation

• NSP-free or NSP-reduced vaccines in combination with a NSP-test lead to a so-called marker-system– Polyprotein Nonstructural Protein(NSP) 3ABC is the single most reliable

indicator of infection– Modern, state of the art-vaccines are based upon highly purified antigens,

which are free from NSP of the FMD virus.– Animals, vaccinated with highly purified( NSP-free vaccines), produce

antibodies against the Structural Proteins (SP) but not against NSP


OIE Recommendation (2006)

Schematic representation of laboratory tests for determining evidence of FMDV infection through or following serological surveys


Vaccine Quality control

Ideal FMD vaccine….• Safe and efficient (FMD control)• Fast & long lasting clinical and virological protection• High potency (minimum number of dose to get protection)• DIVA test (distinction between vaccinated and infected animals): means vaccine

should be free from NSP• Storage (room temperature)• Economical issue (cheap)

OIE and EU recommends the implementation of additional purification steps in the manufacturing process to remove NSP.

EU allows only NSP free vaccines for effective screening and surveillance programs.(EMEA/CVMP/775/02-FINAL)

This week (5/3/10) IVRI has decided to modify their FMD vaccine as per this OIE standard with no/reduced NSP antigens. They are planning to modify the Bangalore vaccine plant for this

(http://www.ivri.nic.in/business/IVRI_Bangalore_FMD_Vaccine_EOI_Notice_050310.pdf )


Differentiation Infected and Vaccinated Animal

Results serology

Conventional test(LPB,VN)

FMDV NSP test

Vaccinated Infected + +

Vaccinated Not infected + -

Not vaccinated Infected + +

Not vaccinated Not infected - -


Immune response of infected and vaccinated animals (cattle)

+ve

-ve

Result

Days after vaccination or infection

4 8 12 16

SP antibodies ( Infected)

SP antibodies (Vaccinated)

NSP antibodies ( Infected )

NSP antibodies (Vaccinated)


Assay Overview and Usage

• Rapid FMD NSP test (available as ‘ubio quickVET FMD NSP’) uses recombinant FMD NSP antigens and monoclonal antibodies to detect the disease.

• FMD 3AB monoclonal antibody on test line• Anti-NSP antibody in serum react with recombinant

FMD antigen labelled with Colloidal gold • This labelled antigen-antibody complex is captured

by the test area forming a red line.


Test procedure

NEGATIVEOnly control

band visible

POSITIVEControl and test bands

visible

INVALIDNo control line, test is

invalid

Collect Blood / whole blood assays can be formatted

Separate serum

Take out the test card from the aluminium foil pouch and place it on a horizontal surface. Add 3 drops of the specimen into sample hole ‘S’

Take 3 drops serum


Ubio QUICKVET FMD NSP test

• Rapid, Immunochromatography based.• One step 10 minutes test.• Can be done directly on serum.• Easy to do in the field.

• Products– FMD-NSP for Bovines– FMD-NSP for Porcines


Recommendation of Kerala

• Post vaccination sero-surveillance for NSP antibodies.

• Border control of slaughter animals.• Screening of animals brought for dairy purpose.


Program flow chart for Screening Dairy

Animals

Veterinary Doctor receives FMD NSP test kits

The doctor visits out-of-the-state purchase site

The doctor examines animals and selects purchase candidates

The doctor collects blood serum from purchase candidates

Serum separation

FMD NSP test

Read test results

Exclude infected animals Finalize Purchase

minutes per animal

minutes

10

2

minutes

6

minute

1


Program Flow Chart for Screening Slaughter Animals

Vehicle arrives at border checkpost

Vet staff at checkpost collects blood serum from all animals. Animals and serum are tagged.

Serum separation

FMD NSP test execution

Read and record test results, issue certificate

minutes per animal per staff

minutes

10

2

minutes

10

minutes

10

Release vehicle

The practical screening scenario 40 animals/TruckWith 3 staff (veterinary doctor and/or livestock inspectors) the total time for one vehicle: 57 minutes. In addition to inspection, the check-post authority will also note animal identification numbers on the issued certificate and on individual animals.ubio can provide custom kits with paired random number identification stickers for this purpose


Vigilance programVigilance team intercepts carriage vehicle or visits

slaughterhouse

Blood serum collected from random animals, serum tagged

based on animal tag

Serum separation

FMD NSP test execution

Read and record test results

minutes per animal per staff

minutes

10

2

minutes

6

minutes

5

Result data compared against test data from checkpost (animal

tag info used as id)

Discrepancies reported, investigation if required


Thank you

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