06 Feb 2004 -- Bangkok/Rome – The United Nations Food and Agriculture Organization (FAO) said on Friday that it had no evidence at this stage that swine were involved in transmission of the H5N1 influenza virus and the spread of the avian influenza epidemic.
“At this time we have seen no data that would indicate that pigs are in any way involved in spreading the current strain of H5N1 influenza virus,” said FAO’s Peter Roeder, a veterinary virologist and animal health expert.
“FAO would advise caution in the interpretation of diagnostic results that have been generated by tests that do not conform to the standards established by the Office Internationale des Épizooties (OIE),” he added.
FAO is aware of two studies carried out in Vietnam this year. An authoritative study, by Professor Robert Webster, Director of the WHO Collaborating Laboratory on Animal Influenza in Hong Kong, showed no evidence of the presence of the H5N1 virus in swine.
“Right now, there is no justification for saying there is H5N1 virus infection in pigs in Viet Nam,” said Professor Webster.
“At this stage nothing has been proven,” he said, “Until either a virus is isolated from within an animal or there are antibodies to show infection the question of transmission remains wide open,” he added.
Webster’s investigation on pigs living in close contact with infected poultry produced no evidence of transmission between the two species, although virologists have known for many years that influenza viruses can pass between species, including swine and poultry.
It would not be surprising if sampling the nasal cavities of swine in any country led to detection of influenza viruses in a small proportion of animals, FAO experts said.
In the face of the current avian influenza epidemic it should not be considered unexpected if the H5N1 virus were to be detected in swine in contact with poultry.
FAO will continue to monitor and investigate the situation closely and will inform countries if there is any reason to believe that the situation is changing.
FAO recommends that all illness that could suggest influenza infection in swine should be reported to the national authorities and thoroughly investigated.
Recent guidelines produced by a joint expert consultation with the World Health Organization (WHO) and the OIE are available on the FAO website.
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