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Bovine babesiosis and anaplasmosis in the Philippines: developing a research and diagnostic capability
Project ID
AS2/2000/098
Project Country
Commissioned Organisation
Queensland Department of Primary Industries and Fisheries, Animal Research Institute, Australia
Project Leader
Dr John Molloy
molloyj@dpi.qld.gov.au
Phone:
07 3362 9413
Fax:
07 3362 9429
Project Budget
$279,749.00
Start Date
01/01/2001
Finish Date
31/12/2002
Extension Start Date
01/01/2003
Extension Finish Date
30/06/2004
ACIAR Research Program Manager
Dr Bill Winter
Overview Objectives
The principal aim of this project was to build a strong diagnostic and epidemiological capability for tick fever in the Philippines, at strategically located laboratories in Manila and Davao. Secondary aims were to improve existing diagnostic tests for tick fever to make them more user-friendly and therefore more suitable for use in developing countries, to conduct epidemiological surveys to determine the prevalence and distribution of tick fever in the major cattle-producing areas in the Philippines and to establish the technology to culture Anaplasma (one of the causes of tick fever) in tick cell culture at the DPI&F laboratories in Brisbane.
Project Background and Objectives
Global losses due to tick-borne diseases (TBDs) have been estimated to be as high as US$18,000 million per annum. Fortunately, in the Philippines and Australia the TBD situation is less complex than in many other countries, with only babesiosis and anaplasmosis, collectively referred to as tick fever, being of economic importance. But an urgent need in the Philippines for reliable, international standard diagnostic capabilities for tick-borne diseases became apparent in recent times. Because their extent within the Philippines was unknown, there were trade disputes over the inferred importation of these diseases in live cattle.
The value of Australia's live cattle trade with the Philippines has been as high as $128 million per annum. But there have been disruptions to that trade, largely due to TBD outbreaks in imported cattle and exacerbated by uncertainties about the disease and the acknowledged lack of diagnostic expertise for TBDs in the Philippines.
This project assisted the regulatory and diagnostic authority, the Philippines Animal Health Bureau (AHB) to acquire technologies that had been developed in other ACIAR-supported projects, in order to understand and deal with tick fever
Progress Reports (Year 1, 2, 3 etc)
Year 1:
1.1 Purpose of Project
The major objective of AS2/2000/098 is to transfer Australian expertise in the diagnosis and control of bovine babesiosis and anaplasmosis to the BAI in the Philippines. At the same time we are adapting new immunoassays (ELISAs) developed in previous ACIAR projects between DPI and Zimbabwe (AS2/91/18 and AS2/96/90) to a more user-friendly kit format suitable for use in the Philippines and elsewhere. By the end of the project we will have provided BAI with sufficient diagnostic reagents and the necessary epidemiological expertise to conduct a nation-wide tick-borne disease survey.
Specific objectives of the project are:
Adapt existing ELISA technology to a more user-friendly kit format suitable for use in developing countries.
Upgrade TBD diagnostic capability in the Philippines.
Determine the distribution, prevalence and impact of TBD in a selected region of the Philippines.
Year 2:
Progress on all project objectives in 2002 is on or ahead of schedule.
Objective 1: Adapt existing ELISA technology to a more user-friendly kit format suitable for use in developing countries.
The ELISAs for B. bovis and B. bigemina assays have been adapted to the most user-friendly format possible. Kits containing pre-coated plates in sealed sachets, enzyme labelled anti-bovine IgG conjugate, colour development and stop solutions, control sera and a full set of instructions for conducting and interpreting the ELISA have been assembled and validated against our bank of known positive and negative sera. The B. bigemina assay uses a recombinant antigen fragment that was developed to improve the sensitivity and specificity of the assay. The B. bovis assay uses a whole merozoite antigen prepared from infected bovine blood.
Objective 2: Upgrade tick-borne disease diagnostic capability in the Philippines.
Transfer of diagnostic tests and reagents
The ELISA kits for B. bovis and B. bigemina and detailed instruction for their assembly have been transferred to the Philippines Animal Health Centre (PAHC) in Manila. The commercially available card agglutination test (CAT) for detecting antibodies to A. marginale and a stockpile of reagents has also been transferred to PAHC. An evaluation of the CAT in comparison with the ELISA marketed by VMRD was undertaken at PAHC and demonstrated better than 90% agreement between the two tests.
The boost in technical support provided by the project allowed us to put additional resources into production of diagnostic reagents. As a result sufficient reagents (antigens and monoclonal antibodies) to test at least 20,000 sera were produced and transferred to PAHC in Manila were they will be used to complete the proposed national serological survey and to assemble ELISA kits as required. The culture system purchased by the project has been invaluable in producing large quantities of monoclonal antibodies for the competitive B. bigemina and A. centrale ELISAs.
Evaluation of PCR based tests for differentiating between Australian and Philippine strains of B. bigemina and A. marginale has been completed. The tests were evaluated with DNA from field strains collected in the Philippines during a project visit in 2001 and our bank of Australian vaccine and field strains. Both tests effectively discriminate between Australian and Philippines strains and will be important tools for investigating the cause of any disease outbreaks in imported cattle.
Training activities
There have been three major training events during the year:
Glenn Anderson conducted a national training course on "The application of the polymerase chain reaction (PCR) and CAT for the diagnosis and surveillance of tick fever and other blood parasites" that was timed to coincide with his scheduled project visit. Representatives of the 13 regional laboratories, the National Dairy Authority and the Philippine Carabao Centre attended the course. Participants gained an appreciation of the potential of molecular techniques for disease diagnosis and strain typing and were able to get some hands on experience with the CAT. The molecular training was particularly relevant given the intention of the Bureau of Animal Industry (BAI) to establish a molecular biology unit at PAHC.
Ivy Cacho, a recent recruit to the project team at PAHC, visited the Animal Research Institute (ARI) and the Tick Fever Research Centre (TFRC) for a 1 month training course in tick fever diagnostics, epidemiology and control practices.
John Molloy, Wayne Jorgensen and Filipino project staff presented a one week "Hands-on workshop on laboratory diagnosis of bovine babesiosis and anaplasmosis: ELISA and microscopy" sponsored by the Philippines Bureau of Animal Industry (BAI) and the ATSE Crawford Fund. Thirty participants from the 13 regional laboratories, city and regional veterinary quarantine offices and the National Dairy Authority attended what was a very successful workshop. Many participants benefited from their first exposure to ELISA and all gained invaluable practice in the microscopic identification of parasites.
Objective 3: Determine the distribution, prevalence and impact of TBD in a selected region of the Philippines.
The serological survey of smallholder owned cattle in the Batangas province south of Manila has been completed. This survey was undertaken as a pilot for the proposed national survey of babesiosis and anaplasmosis to be undertaken by BAI and for the larger surveys proposed for the final year of the project. Indications are that 20.1% of animals have been exposed to B. bovis, 17.4% to B. bigemina and 20.5% to A. marginale. The prevalence of infection varies greatly between regions and between villages within regions. Cattle movement is the most likely factor influencing exposure, the area with the highest exposure being close to a large cattle market and close to commercial livestock enterprises. Despite variable but widespread exposure to both babesiosis and anaplasmosis, cases of clinical disease in smallholder owned cattle are rare, suggesting a high degree of innate resistance in local breeds.
Project Outcomes
The project resulted in the development of centres of expertise in the diagnosis and control of tick fever in the key laboratories in Manila and Davao that service the major cattle producing and cattle importing areas in the north and south of the Philippines. These laboratories are now recognised reference centres for the rest of the country and models for establishing similar expertise in Regional Animal Disease Diagnostic Laboratories (RADDL) throughout the Philippines. Staff from 13 RADDL has already been trained to accurately diagnosis babesiosis and anaplasmosis by microscopic examination of blood smears from sick cattle.
The completion of serological surveys established the distribution of babesiosis and anaplasmosis in the Philippines, with both diseases present virtually throughout the country. DNA based strain-typing tests, developed in the project are now capable of differentiating between Australian and Philippine strains of A. marginale and B. bigemina. These tests will prove invaluable for determining the origin of outbreaks of tick fever that occur periodically in cattle imported from Australia.
Improved diagnostic tests for tick fever are now in routine use in both the Philippines and Australia. As a result of the project the Philippines has been left with a stockpile of diagnostic reagents sufficient to meet foreseeable needs and to conduct further serological surveys as required.
The project facilitated collaboration between the Australian project team and recognized world experts in the USA, that resulted in the capacity to culture A. marginale in tick cells being established in DPI&F laboratories in Brisbane. The ability to culture Anaplasma is critical to ongoing DPI&F research to produce safer and more efficacious vaccines to protect cattle against tick fever.
The project has made a significant contribution toward creating the disease diagnosis and surveillance capability that will underpin the success Philippines government initiatives to build profitable livestock industries. The Philippines government is committed to improving animal health and nutrition and to a programme of importation of breeder cattle to improve the productivity of local beef breeds and to build a viable local dairy industry. A rapid and accurate service for the diagnosis and treatment of tick fever outbreaks in both local and imported cattle is now available. The epidemiological surveys conducted within the project have provided livestock owners and government policy makers with up to date data on the distribution and economic impact of TBD that will allow them to make informed decisions about the future of breeder importation programmes, breed selection and the implementation of tick and TBD control strategies.
The project has benefited both the Philippines and Australia by contributing to the development of a more stable trading relationship based on up to date and clear knowledge. As an example, a recent outbreak of tick fever in cattle imported to the island of Masbate from northern Australia was quickly resolved without any disruption to trade, through rapid and accurate diagnosis of the problem and the ability to demonstrate that the outbreak was due to tick-borne exposure to a local parasite strain after arrival in the Philippines. Demonstration that babesiosis and anaplasmosis already occur throughout the Philippines has largely overcome concerns about the risks associated with the introduction of Australian parasite strains in imported cattle.
The project has also provided a boost to the Philippines government initiative to establish a viable local dairy industry. Cooperation between the project team in Manila and the Philippines National Dairy Authority has identified tick fever as the major cause of disease outbreaks that occur regularly in imported cattle and result in substantial loss of valuable breeding stock. Strategies have now been put in place to minimise tick-borne exposure and vaccinate imported animals on arrival.
The most important impact of the project on rural communities in the Philippines is indirect, and depends largely on the overall success of the government's initiative to improve animal health and nutrition. Should they succeed the long term impact will undoubtedly positive with an increase in rural wealth as a consequence of the increased profitability of livestock industries. A more immediate impact may be and the creation of employment opportunities in rural areas as a result of the growth of feedlots and related industries that rely to a large extent on the smooth operation of the live cattle trade with Australia
Positive benefits to Australia include the availability of improved diagnostic tests and stimulation of ongoing DPI&F research programmes to improve the control of tick fever. In particular, the ability to grow A. marginale in tick cell culture has been a catalyst for the development of several new projects aimed at improving the current tick fever vaccines. The development of an advanced disease diagnosis and surveillance capability in strategic laboratories in Southeast Asia is another positive benefit for Australia in that it contributes to regional biosecurity and acts as an early warning system for Australia's exotic disease surveillance programmes.
Location
There are no project locations defined for this project.
