Avian influenza was first reported in Indonesia in 2003. The highly pathogenic avian influenza strain H5N1 has since spread to 30 of Indonesia's 33 provinces. More than nine million chickens are estimated to have been destroyed or died, with 55 human fatalities also reported, all believed linked to handling infected poultry. The Indonesian Government has opted for control by vaccination, based on strategies developed elsewhere. These are not always appropriate for a geographically diverse country where much poultry production is unstructured. The efficacy of vaccines and multiple strains of avian influenza mean that some vaccinations may not be effective. Scientific knowledge of the virus and its reactions in vaccinated animals will be collated to help develop a more effective and targeted vaccine campaign.
In Indonesia outbreaks of highly pathogenic avian influenza (HPAI) in poultry were first reported in August 2003. Initial cases were not contained and HPAI strain H5N1 has since spread throughout the country, with 31 out of 33 provinces now affected. Mortalities due to H5N1 have occurred in layers, broilers, native chickens, quails, pigeons, aquatic, wild and cage birds. Human infections with H5N1 also continue to occur in Indonesia, with the disturbingly high rate of deaths. Indonesian Government has opted for vaccination as a control measure in order to reduce the incidence of H5N1 infection and thereby the threat to human health. Vaccination has been undertaken in the context of an infection that has become endemic, where a large proportion of poultry are kept under low biosecurity and the unique nature of the H5N1, which has a number of properties not previously encountered in AI. Therefore vaccination strategies developed in countries with good resources, highly structured poultry industries, geographical compactness, and where infections occurred with less aggressive AI viruses, might need to be adjusted.
The strategies used in this project aim to identify the most efficacious vaccination strategy to reduce the incidence of HPAI in poultry. Specifically the project aims are to: (i) Assess the breadth and duration of immunity induced by various inactivated AI vaccines; (ii) characterise AI isolates from poultry vaccinated with selected vaccines (iii) develop reagents to differentiate field infections in vaccinated poultry (DIVA); (iv) develop protocols for investigating apparent vaccine failures for HPAI and (v) develop a simple state-transition model of HPAI infection.
The project is a collaboration between Indonesian Research Center for Veterinary Science (Bbalitvet), Bogor, Indonesia and three organisations in Australia: the University of Melbourne School of Veterinary Science (UoM), CSIRO Australian Animal Health Laboratory (AAHL) and AusVet Pty/Ltd.
The project commenced in late September 2007 when the majority of legal agreements were signed and project development process completed. This includes exchange of material of transfer agreements (MTA) related to the transfer and use of Indonesian HPAI strains in Australia. Initially it was ensured that standardized procedure and reagents are in place enabling comparison of results with other studies conducted internationally and in Indonesia. Baseline collection of data on antibody status in selected commercial flocks has commenced, as has the laboratory trail to establish levels and duration of antibody responses in controlled conditions. It was attempted to source reagents for various DIVA tests that have been published in international literature, but none were available. In the view of changing HPAI situation in Indonesia, several approaches for development of DIVA test have been considered and generation of several different reagents has commenced. Protocols and documentation on how to approach and undertake investigations of vaccination failures have been generated. A simple state transition model was developed and tested using standard parameters. This model appears functionally sound and shows promise as the basis of future modelling scenarios if suitable parameters for the Indonesian situation can be developed.
Links:
[1] http://www.aciar.gov.au/country/Indonesia
[2] http://www.aciar.gov.au/programarea/Animal Health