Đề tài Development of an Improved Capability in support Milestone

1 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 1 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 1 1. Institute Information 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 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 in southern Vietnam. Through implementation of this project one of the lessons learnt has been the importance of complete and accurate field information. Whereas the laboratories were already accustomed to recording results, the recording of information such as vaccination and infection data in the field was not commonplace. Data collection and management has improved dramatically throughout the project. The only downside of this is that data quantity and quality for the initial rounds is difficult to analyze for the purpose of investigation of vaccine failure. In addition to this the accuracy of some of the data is questionable, as is discussed throughout this report. 3 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. 4 An Giang Cattle Year (Round) Vaccination % 3ABC + % O ELISA + % A ELISA + % Asia 1 + Previous Infection date in province (species, serotype) Comment Type Vaccination- sampling interval August 2005 (pigs, O) 2008 (6) O,A 2mths 36 89 100 51 August 2005 (pigs, O) 2008 (5) O,A 5mths 10 10 22 9 August 2005 (pigs, O) 2007 (4) O,A 1mth 21 61 58 0 August 2005 (pigs, O) 2007 (3) O,A 6-7mth 37 66 47 31 August 2005 (pigs, O) Higher proportion Asia 1 +ves amongst 3ABC+ group 2006 (2) O,A 6mth 38 19 56 34 August 2005 (pigs, O) Proportions across the 3ABC- /3ABC+ similar 2005 (1) O,A Unknown 76 63 70 56 August 2005 (pigs, O) Unknown history of infection 0 10 20 30 40 50 60 70 80 90 100 Percentage 1 2 3 4 5 6 Round Percent cattle O/A positive when vaccinated for that serotype O A 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 positive for all 3 serotypes. This suggests that these cattle have been vaccinated with either a 5 bivalent or trivalent vaccine, given that infection with more than one serotype simultaneously 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). 6 Conclusions The % of cattle 3ABC was > 1/3 in 4 of the 6 rounds. In the absence of outbreak history or isolates from this province since 2005 this suggests that: ™ There has been movement (transboundary or between provinces) of infected (diseased or carrier) animals ™ 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 2008 (6) No samples 2008 (5) No samples 2007 (4) O 1mth 0 5 0 0 August 2005 (pigs, O) 2007 (3) O 6mths 0 5 0 0 August 2005 (pigs, O) 2006 (2) O 6 mths 0 0 0 0 August 2005 (pigs, O) 2005 (1) No samples 7 0 10 20 30 40 50 60 70 80 90 100 Percent 2 3 4 Round Percent pigs O/A positive when vaccinated for that serotype O Samples were collected from vaccinated pigs in 2006 and both rounds of 2007. The highest serological response for serotype O was 5% despite the fact that on one occasion vaccination was administered just one month prior to sampling. In rounds 2 and 3 all sampled piglets were >6 months. In the remaining rounds some piglets were as young as 2.5 months, so could not have been vaccinated on the date recorded. Binh Phuoc Cattle Year Vaccination % 3ABC + % O ELISA + % A ELISA + % Asia 1 + Previous Infection date in province (species, serotype) Comment Type Vaccination- sampling interval 2008 (6) O,A,Asia1 1mth 24 94 93 93 2006 (Cattle, pig; O) Last infection Aug 05 2008 (5) O,A,Asia1 5 mths 28 34 51 18 2006 (Cattle, pig; O) ½ that have been infected are Asia + 2007 (4) O, A 1 mth 14 89 88 38 2006 (Cattle, pig; O) 2007 (3) O,A 5-6mths 9 41 81 55 2006 (Cattle, pig; O) 2006 (2) O,A,Asia1 9 mths 11 50 35 35 2006 (Cattle, pig; O) Previous infection (O/A?) 2005 (1) O, A 4 mths 10 20 5 24 April, Aug, Oct 2005 (Cattle, O/A; pigs, O) 8 0 10 20 30 40 50 60 70 80 90 100 Percentage 1 3 4 5 6 Round Percent of cattle O/A/Asia1 positive when vaccinated for that serotype O A Asia1 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. Sub- 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 variation in % positive for each serotype. 9 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. 10 Pigs Year Vaccination % 3ABC + % O ELISA + % A ELISA + % Asia 1 + Previous Infection date in province (species, serotype) Comment Type Vaccination- sampling interval 2008 (6) O 1mth 0 0 0 0 2006 (Cattle, pig; O) Most piglets 2-3 mths 2008 (5) None None 14 0 0 0 2006 (Cattle, pig; O) 2007 (4) O 1mth 0 0 0 0 2006 (Cattle, pig; O) Age unknown 2007 (3) O 1mth 0 0 0 0 2006 (Cattle, pig; O) Age unknown 2006 (2) None None 0 17.5 0 0 2006 (Cattle, pig; O) 2005 (1) None None 0 0 0 0 April,