The use of gamma irradiation for the inactivation of infectious bursal disease viruses.

The maximum dosage of gamma irradiation approved by the U.S. Food and Drug Administration (FDA) for poultry is 3.0 kiloGrays (kGy). This treatment is designed to reduce bacterial contamination on uncooked poultry carcasses and meat products. The possible presence of infectious bursal disease virus (IBDV) on poultry postharvest has prompted some countries to study the risk associated with introducing nonnative strains of the virus from imported commodities. The goal of this study was to determine if this risk could be reduced using gamma irradiation to inactivate IBDV. At the dosage approved by the FDA, the titers of IBDV vaccine strains were reduced between 0 and 1 log10. Titers of the pathogenic IBDV strains tested were not reduced after the 3.0 kGy exposure. Furthermore, titers of pathogenic viral strains were not reduced following exposure up to 5.0 kGy. As the exposure to gamma irradiation increased, the titers of the vaccine strains decreased. At the maximum dosage tested (10 kGy), the 89/03 variant virus vaccine was completely inactivated. Titers of the three classic IBDV vaccine strains were reduced between 1.6-2.0 logs after the 10 kGy exposure; however, these viruses remained viable after this treatment. Gamma irradiation is not an effective intervention to reduce the risk of IBDV introduction via processed poultry.

The impact of new epidemiological information on a risk analysis for the introduction of avian influenza viruses in imported poultry meat.

New Zealand has never experienced an outbreak of avian influenza, and the Ministry of Agriculture and Forestry has long been wary of the possibility of introducing high-pathogenicity avian influenza (HPAI) viruses in imported goods. Besides the potential threat posed to poultry, there are concerns that introduced viruses might have negative effects on already endangered native avian species. Under the framework of the World Trade Organization, the sanitary and phytosanitary (SPS) agreement requires member countries to base their sanitary measures for imported animal products on the Office International des Epizooties (OIE) standard or on a scientific assessment of risk. This paper presents the New Zealand experience with assessing the risk of avian influenza viruses in imported chicken meat and considers how the assessment of risk has changed in recent years as a result of the advances in understanding of the disease. The currently accepted view that low-pathogenicity avian influenza (LPAI) viruses are widespread and that they mutate to virulence after introduction into poultry has important implications concerning the appropriate definition for avian influenza viruses of regulatory concern and has possible implications concerning the significance of viruses present in this country.

Risk analysis: assessment, management and communication.

Import risk analysis is now a well-established discipline which aims to assist Veterinary Services to answer the following questions: 'What can go wrong?', 'How likely is it to go wrong?', 'What would be the consequences of it going wrong?' and 'What can be done to reduce either the likelihood or the consequences of it going wrong?'. Risk communication is that part of the overall process which, among other things, helps the decision-maker to determine whether a particular risk is acceptable or not. Good risk assessment and communication are dependent on clear formulation of the question to be answered. Scenario trees and influence diagrams are very useful tools in assessing and communicating risk. The authors outline the import risk analysis procedures adopted by the Veterinary Services of one Member Country of the OIE (World organisation for animal health).

Foot-and-mouth disease: an assessment of the risks facing New Zealand.

Although New Zealand has never had a case of foot-and-mouth disease (FMD), the threat that this disease poses to the economy of this country has long been recognised. The unprecedented global spread of FMD caused by the type-O PanAsia strain, culminating in the outbreak that occurred in the United Kingdom in early 2001, has refocussed the concerns of biosecurity agencies worldwide. The 3 lines of defence against exotic disease incursions in this country are border controls, surveillance and incursion response capability. This article reviews the pathogenesis, virus survival, routes of infection and methods of spread of FMD virus, and in the light of recent international developments, presents a summary of the major risks of introduction and dissemination of FMD virus and the risk-management measures in place for this country.

The control of bovine tuberculosis in New Zealand.

Mycobacterium bovis was probably introduced into New Zealand with cattle imported in the early 19th century. A tuberculosis control programme was introduced for cattle in 1945. However, the control of tuberculosis in cattle and deer in New Zealand over the past two decades has been hampered by the presence of an important wildlife reservoir, the Australian brushtail possum (Trichosurus vulpecula). While the importance of this source of infection has been suspected by the Ministry of Agriculture for some time, scientific proof has been lacking until recently. A new control programme is currently being finalized with the following objectives: to reduce the prevalence of herd infection in vector free areas to internationally accepted levels, to prevent the establishment of tuberculous vectors in new areas, to decrease the number and size of existing areas where tuberculous vectors exist, and to encourage land-owners to take action against tuberculosis on their properties and in their herds.

Progress in the use of computerised recording systems in dairy cow monitoring and extension in Malaysia.

The emphasis on cow records in Malaysian dairy extension programmes reflects the importance of herd fertility in the economics of dairying. Manual record keeping has not been able to make an impact on management due to difficulties experienced in quality control of the data and in analysing the data to produce useful information for farm managers. Computerised recording systems have been in use in Malaysia since 1985, both on government farms and in the small-holder dairy sector. The aim of both systems is firstly to improve farm efficiency by the provision of information to managers and extension workers and secondly to provide information for departmental planning purposes. The systems used in Malaysia are outlined, and the results over the first three years of operation are summarised.

Analysis of clinical case records from dairy co-operatives in Bangladesh.

Records of 28,266 clinical cases collected over a period of three years from a veterinary clinical service to small dairy farms in Bangladesh were analysed. The major clinical conditions encountered were those which adversely affect the performance of draught animals and those causing infertility. Gastrointestinal disorders and general debility were also of major significance. It was concluded that the most pressing constraint on cattle productivity in Bangladesh is inadequate nutrition. Although infectious diseases were of minor importance overall, annual epidemics of foot-and-mouth disease were associated with seasonal movement of cattle. Difficulties involved in the analysis of clinical case records are discussed.