Báo cáo nghiên cứu khoa học " Development of an Improved Capability in support of National Bio-security for the Surveillance and Control of Foot & Mouth Disease in Cattle and Pigs - Milestone 6 " ppt

2006 Round 2 All cattle were vaccinated for serotypes O/A, 6months prior to sampling.. 2007 Round 3 Vaccination was 6 months prior to sampling with O/A vaccine.. 2007 Round 4 Vaccinat

Ministry of Agriculture & Rural Development

CARD Project Technical Report

Development of an Improved Capability in support of National Bio-security for the Surveillance and Control of

Foot & Mouth Disease in Cattle and Pigs

Milestone 6 Epidemiological and sero-surveillance programs operational

By Debbie Eagles & Chris Morrissy

Table of Contents

1 Institute Information _ 1

2 Project Abstract _ 3

3 Executive Summary 3

4 Introduction & Background _ 4

5 Epidemiological and Sero-surveillance programs 4

5.1 Implementation Highlights 4 5.2 Capacity Building _ 36 5.3 Publicity _ 36

6 Implementation & Sustainability Issues _ 37

6.1 Issues and Constraints _ 37 6.2 Options 37 6.3 Sustainability _ 37

7 Next Critical Steps 38

8 Conclusion 39

Project Name

Vietnamese Institution Regional Animal Health Centre, Ho

Chi Minh City (RAHO - 6 ), South Vietnam

Vietnamese Project Team Leader Dr Dong Manh Hoa

Australian Organisation Australian Animal Health Laboratory

(AAHL), PMB 24, Geelong, 3213, Australia

Australian Personnel Mr Chris Morrissy

Date commenced 01/06/2005

Completion date (original) 01/06/2008

Completion date (revised)

Reporting period

Contact Officer(s)

In Australia: Team Leader

Name: Mr Chris Morrissy Telephone: +61 3 5227 5000

Position: Diagnostic Virologist

Supervisor Mammalian Virology Fax: +61 3 5227 5555

Organisation Australian Animal Health

Laboratory (AAHL), PMB 24, Geelong, 3213,

Australia

Email: chris.morrissy@csiro.au

In Australia: Administrative contact

Name: Mr Chris Morrissy Telephone: +61 3 5227 5000

Position: Patents Contracts Officer Fax: +61 3 5227 5555

Organisation Australian Animal Health

Laboratory (AAHL), PMB

24, Geelong, 3213, Australia

Email: christopher.morrissy@csiro.au

In Vietnam

Name: Dr Dong Manh Hoa Telephone: + 84 8 8568220

Position: Director Fax: + 84 8 8569050

Organisation Regional Animal Health Centre,

Ho Chi Minh City (RAHO - 6 ), South Vietnam

Email: rahchcmc@hcm.vnn.vn

2 Project Abstract

The project’s purpose was twofold - to develop capacity for FMD (and other disease) surveillance and diagnosis at both a laboratory and field level, and to investigate the serotypes of FMDV circulating in Vietnam and the reason for vaccine failures Regional laboratories were set up with the reagents and methods to allow a diagnostic capability for FMDV diagnosis and serology Control strategies for understanding of FMD epidemiology have been implemented through veterinary and laboratory training workshops The project has highlighted the importance of having a laboratory network to identify what is happening

in the field and how to prevent and control disease outbreaks The pilot zones were established in provinces near the borders of Vietnam to study serotypes circulating in Vietnam and to determine their origin The number and quality of samples increased with each round of the project giving more data on the FMD situation in Vietnam Virus isolation and molecular studies can now be carried out on FMD samples from the field and molecular epidemiological studies of the FMDV isolates in these provinces has provided insights into the effectiveness of border control and origin of circulating FMDV Improved diagnostic capacity for FMD allows for the early detection and identification of disease enabling better control of disease and helps reduce loss of livestock and therefore increases productivity

3 Executive Summary

The CARD FMD project was ambitious in that it had 2 very broad and diverse aims The first objective was capacity building – at the laboratory, epidemiological and field levels The second major aim was to investigate possible causes of vaccination failure by evaluating isolates of circulating strains and sero-surveillance data

The project was very successful at achieving its objective in relation to capacity building As documented in the final report, the four collaborating Vietnamese laboratories improved their FMD diagnostic capacity and have been able to apply their new skills to disease investigations and surveillance projects

In addition, there have been important and measurable improvements in both epidemiological and field areas When this project began there was no epidemiology department at any of the laboratories There is now a fully functional epidemiology department, with 3 full-time staff,

at RAHO – 6 This group has been instrumental in supporting this and other international projects and has provided advice and training to field and provincial veterinarians They have also been crucial to investigation of disease outbreaks such as HPAI and PRRS, particularly

With the laboratory and epidemiological capacity now available in the collaborating laboratories, particularly HCMC, there is now the potential for a smaller, more focused study

on vaccination failure This would be best limited to a smaller number of provinces in southern Vietnam, with a study protocol aimed specifically at investigating vaccination effectiveness

4 Introduction & Background

Serum samples and information were initially to be collected from 10 provinces – An Giang, Binh Phuoc, Dong Thap, Kien Giang, Kom Tum, Lang Son, Long An, Quang Nam, Quang Ninh and Tay Ninh No samples were ever collected from Lang Son Samples were also only collected intermittently from the other northern province in the project, Quang Ninh The central provinces of Kom Tum and Quang Nam provided samples for all but the 3rd round

In the southern provinces samples were not available from Long An in the final round and

An Giang did not provide pig samples in round 1, 5 or 6 The epidemiological support and interest at RAHO - 6 is almost certainly a contributing factor to the better provision of samples from the southern provinces A combination of fewer specialized staff in the northern provinces and laboratories and the required allocation of resources to outbreak response is likely to have reduced their ability to collect samples NCVD did not have a epidemiology section

In 2005, the field data collection and the use of forms was not well developed As a result, for most provinces the only information collected was species, sampling location (district/commune/village) and in some instances vaccination information, sampling date and animal age

In 2006 the data collection form was further developed and standardised with the following fields – district, commune, village, species, age, sex, sampling date, vaccination date, vaccine name/manufacturer/serotypes, last date of infection, last serotype of infection and field sample number This form improved data collection dramatically although not all fields were completed in every round for each province

5 Epidemiological and Sero-surveillance programs

5.1 Implementation Highlights

Analysis by Province

The analysis for the information in each province is divided into cattle and pigs For each species there are tabular results and a graph followed by a description of the results for each round The graph only displays information for rounds and serotypes for which animals have been vaccinated ≤ 6 months prior to sampling

% O ELISA +

% A ELISA +

% Asia

1 +

Previous Infection date in province (species, serotype)

Comment

Type Vaccination-

sampling interval

2005 (Round 1)

Without vaccination or infection information available no judgment can be made on vaccination response 75% cattle were NSP ELISA positive, and more than half of these are

is rare Further testing of the sera is necessary to determine the serotypes present, ie titration

of the sera to a endpoint against each sera type

There was a reported outbreak of serotype O infection in pigs in 2005

2006 (Round 2)

All cattle were vaccinated for serotypes O/A, 6months prior to sampling The greatest serological response was to serotype A at 50% It is likely that there was a problem with the sensitivity of the O ELISA for this batch of samples, as it would be unlikely for animals to have been vaccinated for serotype A and not serotype O It is almost certain that some animals were also vaccinated for Asia 1, given the serological response to this serotype, absence of outbreak history and the negative 3ABC result in the majority of those that were Asia 1 positive

2007 (Round 3)

Vaccination was 6 months prior to sampling with O/A vaccine Despite lack of infection history, 37% were 3ABC ELISA positive In general the serological response to serotype O was better than in the previous round which may be more indicative of changes to the assay

as opposed to differences in vaccine response

Close to a third of cattle were also positive on the Asia 1 ELISA and of these 2/3 were also 3ABC positive This is suggestive of both unrecorded vaccination and/or unreported infection (which may be related to animal movement)

2007 (Round 4)

Vaccination occurred one month prior to sampling with an approximately 60% response rate

to both serotype O and A (bivalent vaccine administered) A smaller % were positive on the

3ABC ELISA in this round than in round 3

2008 (Round 5)

The serological response to the O/A vaccine is very poor, regardless of the 5 month interval between vaccination and sampling Following the protocol listed below in Appendix 1 (Investigating Vaccination Failure Checklist) may assist in determining the reasons for

vaccine failure Records suggest that the same vaccine was used in each round

2008 (Round 6)

There was an excellent serological response to vaccine in this round, in which the vaccination-sampling interval was 1 month Over 50% of cattle also seroconverted to Asia 1 despite no history of recent vaccination for this serotype Half of these were also 3ABC

positive, despite no infection history in the sampled animals or the province (see below)

™ There have been unreported or undetected (due to mild clinical signs) infections in

the surveyed communes

™ There is a large number of animals previously exposed to FMD or carriers that remain – at least intermittently – NSP ELISA positive

Some variation in the results between years may also be due to the inclusion of 4 communes (An Phu, Tinh Bien, An Nong and Nhon Hung) which were variably sampled in the different rounds

Vaccination response was only – in the final around - above the required herd protected level

of 80%

Pigs

Year Vaccination %

3ABC +

% O ELISA +

% A ELISA +

% Asia

1 +

Previous Infection date in province (species, serotype)

Comment

Type Vaccination-

sampling interval

Binh Phuoc

Cattle

Year Vaccination %

3ABC +

% O ELISA +

% A ELISA +

% Asia

1 +

Previous Infection date in province (species, serotype)

Comment

sampling interval

0 10 20 30 40 50 60 70 80 90 100

2005 (Round 1)

There is little field information available for this year, as the forms for information collection had not been developed Cattle were vaccinated 6 months prior to the sampling date with O/A vaccine, which is just at the extent of the expected vaccination protective period The vaccination response rate in this year was very poor (20% positive for serotype O and 5% positive for serotype A), however it is difficult to pass judgment on first year results from either field or laboratory perspective

2006 (Round 2)

In this year the recorded information shows that vaccination was with a serotype A vaccine called Trivale However discussions at sub-DAH confirm that, as the vaccine name would suggest, this is more likely a trivalent vaccine The manufacturer is unknown The vaccination date was 9 months prior to sampling date, so it is not surprising that the seropositives were relatively low at 50%, 35% and 35% for serotypes O, A and Asia 1 respectively

2007 (Round 3)

In this year records suggest that all cattle were vaccinated with serotypes O/A vaccine DAH staff again suggested that cattle may have been vaccinated for Asia1 This would fit the ELISA results, with 41%, 81% and 55% positive for O, A and Asia1 serotypes respectively The vaccine was administered 5 months prior to sampling, which may contribute to the

Sub-2007 (Round 4)

In this year cattle were vaccinated with serotype O/A vaccine one month prior to sampling The seropositivity for both these serotypes was around 90% suggesting excellent vaccination response 38% of cattle were also positive to serotype Asia1 (see round 3) A relatively small

% of animals were 3ABC positive

2008 (Round 5)

In this year cattle were vaccinated with a trivalent vaccine The seropositives were 34%, 51% and 18% again for O, A, and Asia 1 serotypes respectively The vaccine was administered 5 months prior to sampling, which may partly account for the lower seropositivity than seen in rounds 4 and 6 However, this time interval is still within the expected protective period of the vaccine Staff at Sub-DAH suggest that of the cattle presented for vaccination approximately 70% are re-presented for sampling, the remaining 30% may be different animals Although all cattle in the district should have been vaccinated at the same time, some of the animals presented for sampling may be new to the province and possibly unvaccinated

One quarter of cattle sampled were positive for 3ABC ELISA suggesting previous infection Most of these were positive for all 3 serotypes, and as vaccination in this year was also for all

3 serotypes it is not possible to determine the serotype of infection Titration of positive samples may have assisted, in there was clearly a 4-fold difference in titrations between one serotype and the remaining 2 serotypes

2008 (Round 6)

There was an excellent response to the O/A/Asia 1 vaccine (Aftopor) used in this round with 90% or more seropositivity for all serotypes As per the first round in 2008, one quarter of the cattle were also 3 ABC positive, indicating previous infection

Conclusions (cattle):

Vaccination response rates for cattle in Binh Phouc were generally very good and, with the exception of round 5, improved throughout the project As expected, the proportion of vaccinated animals seropositive was much higher in those sampled 1 month after vaccination, as opposed to those vaccinated 5 months previously However, this is a concern

as vaccination is meant to be protective for 6 months

Trans-boundary movement and movement of animal between provinces may also have contributed to some of the variation in results, particularly if these animals have previously been infected, and not recently vaccinated Interestingly, there was a spike in % positive on 3ABC ELISA in the 5th round despite no history of vaccination since 2006 This is the same round in which there was poor vaccination response, suggesting a possible influx of unvaccinated, previously infected animals to the district

Pigs

Year Vaccination %

3ABC +

% O ELISA +

% A ELISA +

% Asia

1 +

Previous Infection date in province (species, serotype)

Comment

Type Vaccination-

sampling interval

2007 (Round 4)

As for round 3, the results in pigs do not match the vaccination history with no seropositive pigs despite serotype O vaccination 1 month prior to sampling There may be a number of reasons for this, including specifics of the ELISA assay, sampling after only one vaccine (rather than the initial two required for complete vaccine response) or the vaccinating and

sampling of 2 different groups of pigs Again age records have not been kept for these pigs

this round were only 2-3 months old they are likely to have only had one vaccine, if any

Conclusions (pigs)

In pigs field and laboratory information did not concur Further investigations and trials would be necessary to determine the issues but it is likely a major contributing factor is the presentation of different pigs for vaccination and sampling, or sampling after just one vaccination

Dong Thap

Cattle

3ABC +

% O ELISA +

% A ELISA +

% Asia 1 +

Previous Infection date

in province (species, serotype)

Comment

sampling interval

2008 (6) O,A

O, A, Asia

1

1-3mth 4mth 24 20 61 60 70 90 10 5 2008 (pig, O) September

O,A,Asia1

None None

<6mths + I (O)

<6mths

>6mths 1mth + I (O) 1mth + I

0 10

2005 (Round 1)

There was no vaccination history for this round 40% show indication of previous infection Outbreaks of FMD in pigs were reported in 2004 and 2005 but no infection in cattle is recorded

2006 (Round 2)

The large variation in vaccination history and the resultant small group size for each category make this information difficult to analyse In general, the vaccine response appears to be reasonable

2007 (Round 3)

In this round cattle were vaccinated with trivalent vaccine 2, 3 or 6 months prior to sampling

or O/A vaccine 3 months prior to sampling The graph below compares the % cattle with antibodies to all 3 serotypes (and 3ABC) based on vaccination-sampling interval for those vaccinated with trivalent vaccines This clearly shows the drop over time of protective

antibodies

A large proportion of cattle reportedly only vaccinated with a bivalent vaccine were also

positive on the Asia 1 assay

0 20

2008 (Round 5)

In this round the vaccine type was unknown but likely to be either bivalent or trivalent, given the high seropositivity on all 3 ELISAs (80%, 90% and 60% for O, A and Asia 1 respectively)

2008 (Round 6)

Most of the cattle were vaccinated with bivalent (O/A) vaccine in this round, 1-3 months prior to sampling There were also 9 cows that reportedly received trivalent vaccine, yet there was a very low proportion of cattle seropositive on the Asia1 ELISA from this group, suggesting that they perhaps received a bivalent vaccine also It is possible that the O ELISA has a lower sensitivity than the A ELISA, as evidenced by the lower % positives when vaccinated against both serotypes

Conclusions

Dong Thap provided excellent vaccination history – it appears that vaccination history was recorded separately for each animal sampled as opposed to a generic vaccination history for all animals Despite this, vaccine responses were still variable but best in the final round Dong Thap experienced a number of outbreaks of FMD (both O & A serotype) during the project period and this, along with their commitment to data collection, would make this province ideal for any further studies

Pigs

3ABC +

% O ELISA +

% A ELISA +

% Asia 1 +

Previous Infection date in province (species, serotype)

Comment

sampling interval

2006 (2) O

O None

Kien Giang

Cattle

Year Vaccination %

3ABC +

% O ELISA +

% A ELISA +

% Asia

1 + Previous Infection

date in province (species, serotype)

Comment

Type Vaccination-

sampling interval

In this round the vaccination and infection history is unknown There are no known recorded outbreaks in this province from this or preceding years but there is a very high proportion of seropositives for the 3ABC ELISA Of those cattle that are 3ABC ELISA positive 81% are also O ELISA positive (Of the 3ABC negative group only 33% are O ELISA positive), suggesting a possible previous (recent) infection with that serotype

2006 (Round 2)

Although vaccination is known to have been with O/A vaccine in this round the date of vaccination is unknown If vaccination occurred within the 6 month protective period the % positives are very low, sitting just above 50% for both vaccinated serotypes

2007 (Round 3)

Vaccination occurred 5 months prior to sampling, which is within the protective period of the vaccination, the response rate on ELISAs is very poor All cattle were vaccinated with O/A vaccine yet there was only around ¼ seropositives on each of these ELISAs

2007 (Round 4)

In this round the % seropositives is relatively good, as would be expected for a sampling period of 1 month However it is still of some concern that if all cattle were definitely vaccinated with O/A vaccine that 1 month post vaccination only 64% were positive for serotype A There are two main possibilities for this – that there is an antigen “mismatch” between the vaccine and the ELISA, or that some animals have been vaccinated with a serotype O vaccine only

vaccination-2008 (Round 5)

All cattle were vaccinated 5 months prior to sampling with O/A vaccine In both this and round 6 there is a significantly lower proportion seropositive on the O ELISA than the A ELISA It would be extremely unlikely for cattle to be vaccinated for serotype A only, so this suggests a problem with the sensitivity of the O ELISA assay In addition to this the proportion of ELISA A+ is greater amongst the 3ABC +ve group than the 3ABC –ve group, which suggest there may also be some animals previously infected with this serotype

2008 (Round 6)

In this round the vaccine is the same as for round 5 but with a vaccination-sampling interval

of 1 month The proportions positive to the O and A serotypes are not dissimilar to round 5 Proportions of O and A ELISA positives are both roughly the same between infected and uninfected groups

Conclusions

Vaccine response to serotype A improved each round In contrast serotype O vaccine response declined from round 4 to rounds 5 and 6 As vaccination with serotype A alone is not common, this is suggestive of an issue with the sensitivity of the O ELISA

Pigs

Year Vaccination %

3ABC +

% O ELISA +

% A ELISA +

% Asia

1 +

Previous Infection date in province (species, serotype)

Comment

Type Vaccination-

sampling interval

O

either 1 or 5 months, or in some cases unknown The percentage seropositives for the O ELISA varied from 0% (when vaccination date 5 months previous, or unknown) to 35% when the vaccine was administered 1 month prior to sampling In all rounds were ages were recorded pigs were greater than 4 months of age

Kom Tum

Cattle

Year Vaccination %

3ABC +

% O ELISA +

% A ELISA +

% Asia 1 +

Previous Infection date in province (species, serotype)

Comment

Type Vaccination-

sampling interval

2006 (2) O,A,Asia1 7mth 0 60 10 23 None

2005 (1) O,A,Asia1 Unknown 0 31 4 12 None

0 10

2005 (Round 1)

Again, vaccination date and infection history are unknown for this round A large vaccination-sampling interval may explain the variation in proportion seropositive against each vaccinated serotype

2006 (Round 2)

The 7 month vaccination-sampling interval may partly explain the variation in seropositives between O, A and Asia1 serotypes for which these animals were vaccinated However, it is also possible that some animals were vaccinated with O vaccine only (due to the significantly higher % of positives on this ELISA) No animals had history of infection or reacted on the 3ABC ELISA

2007 (Round 3)

No samples collected or tested in this round

2007 (Round 4)

Given the short period between vaccination and sampling the % seropositives for each of the

3 vaccinated serotypes is very low In this round, as compared to others, there was a very high proportion of animals positive on the 3ABC ELISA These animals did not have a history of infection and there were no recorded outbreaks in the province As such, the high number of animals NSP ELISA positive may be due to any one or combination of the following:

™ Movement of infected animals (from other provinces or countries)

™ Unreported/undetected (mild clinical signs) infection

™ Large number of carriers that remain (at least intermittently) NSP ELISA positive

Interestingly the same communes and villages were used in rounds 2 (no samples collected in round 3) and round 5 Most of the 3ABC positive animals were from one commune (Dak Nong), only one animal was 3ABC positive from the other commune (Bo Y) Samples from this round were taken late (ie January 2008) and the samples in round 5 were taken in April

2008 With just 3 months between sampling, it would be expected that if the same animals were tested the proportion of those positive to 3ABC ELISA would be higher than the 5% seen in round 5 Titrating the positive samples for 3ABC and for each of the LP ELISAs in this round may have helped determine the serotype responsible for infection This may give some indication of the source of infection (if there were reported outbreaks in nearby provinces/countries) however questioning of farmers may also be required

2008 (Both rounds 5 and 6)

In both these rounds cattle were vaccinated for serotypes O and A In round 5 this was 5 months prior to sampling and in round 6 it was 2 months prior to sampling The vaccine response rate is extremely poor for all serotypes in both rounds This is suggestive of major

vaccine failure or, contrary to the recorded information, no vaccination