H5N1 bird flu virus is changing
FAO and OIE recommend increased surveillance when vaccinating
8 November 2006, Paris/Rome - According to a report in last week’s Proceedings of the National Academy of Sciences on the identification of a new H5N1 virus sublineage in poultry, this new virus sublineage, called Fujian virus, appears to have become the dominant strain of the H5N1 avian influenza circulating in parts of Asia. If the report is confirmed, this does not come as a surprise, FAO and the World Organisation for Animal Health (OIE) said today.
While there is a wide variety of avian influenza strains in animals, and influenza viruses in general have a high rate of change from season to season and from year to year, OIE Director-General Bernard Vallat and FAO’s Chief Veterinary Officer Joseph Domenech warn that with new antigens developing continually in avian influenza viruses, vaccines currently in use for poultry need to be assessed regularly.
The two organizations continue to recommend that vaccination control measures need to be accompanied by surveillance and post-vaccination monitoring. They also stressed the need to immediately report to veterinary authorities any unexpected poultry deaths.
Careful monitoring of vaccination campaigns recommended
Vaccination remains part of the FAO-OIE strategy to contain avian influenza and both organizations say that vaccination campaigns should be applied appropriately and carefully monitored according to FAO and OIE technical guidelines, including the use of a cold chain in order to protect the vaccine. Vaccination must be carried out along with other disease control measures, such as improved hygiene on the farm, animal movement management or market inspection and culling in case of outbreaks, said Dr Domenech.
According to Dr Vallat, “Commitment is needed from all governments to implement prevention and control programmes such as surveillance of virus circulation and, where appropriate, vaccination programmes in countries where the virus is endemic or where there is a high risk of introduction of the virus.”
FAO and OIE are already supporting such programmes in key countries where the virus is still circulating. But, they say more information on control programmes based on vaccination is needed and urge more research be funded to better understand the epidemiology and genetic changes of the H5N1 virus
FAO, the OIE and a myriad of scientific experts on avian influenza have repeatedly called upon scientists around the world to share their findings and virus strains in a timely and transparent fashion. The OIE/FAO Avian Influenza Laboratory Network with its secretariat in Padova, Italy (OFFLU - http://www.offlu.net) is a platform where member countries and scientists can share valuable information with the international veterinary and medical community. It is imperative that global health concerns and timely information sharing override lags in the scientific publications approval process, which may take from a few months to more that a year.
It is essential during outbreaks that pathogens, such as highly pathogenic avian influenza virus, be isolated from clinical cases and that any changes in the character of the virus be monitored to ensure that vaccine manufacturers are producing vaccines complying with OIE standards which are effective against virus strains in circulation, said Dr Domenech.
Should the changes be significant enough to warrant reformulation of the vaccine, FAO and the OIE say it would be in the best interest of global health for this to be done by national governments and commercial vaccine companies.
Scientists from such institutes as Istituto Zooprofilatico Sperimentale (Italy), Veterinary Laboratories Agency (UK), Southeastern Poultry Research Laboratory (USA), Australian Animal Health Laboratory, and Friedrich Loeffler Institute (Germany) have voiced their support for the FAO and OIE position that vaccine delivery alone is insufficient to halt virus circulation and to protect animal or human health.
“In an area where poultry populations have been vaccinated, well-planned serological studies must be conducted with full disclosure of the modalities of vaccination use in the poultry population, including the use of the cold chain and types of vaccines and date of last vaccination so results can be clearly interpreted,” Dr Vallat said.
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