It may be because virus mutations have made the current vaccines for poultry less effective.
"A change in bird flu virus strain H5N1 has diminished the effectiveness of vaccines against the disease among poultry, local newspaper Pioneer Thursday quoted a local official as saying.
Bird flu vaccines are produced according to the gene type Z found in bird flu virus strain H5N1 in 2003 when Vietnam was first hit by the disease, but another gene type called G was detected in 2005, said Nguyen Tien Dung, head of the Ultra-Virus Department of the Veterinary Institute under the Ministry of Agriculture and Rural Development.
The gene type Z and type G are not very similar, so the vaccines are more effective to the type Z, and less effective to the type G, he said, noting that first infected poultry with the type G in Vietnam were mainly smuggled.
Vietnam is strengthening bird flu vaccinations among fowls nationwide, using the vaccines imported mainly from China and the Netherlands, according to the ministry's Department of Animal Health."
http://news.xinhuanet.com/english/2007-05/31/content_6179028.htm
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment