Bird Flu In More Asymptomatic Ducks in Vietnam
Recombinomics Commentary
January 14, 2005
>> According to a report from the Veterinary Department of the Ministry of Agriculture and Rural Development on Thursday, the bird flu situation has become more complicated. On Tuesday and Wednesday, there were six new bird flu areas detected at six communes, five districts and My Tho city in Tien Giang and Ben Tre provinces. In the past two days, 2,660 chickens and 7,000 quails have been culled. At the locations of the new outbreaks, the number of poultry that have died low but the disease has quickly spread. On Wednesday, the disease hit some farms in Tan My Chanh commune, My Tho City and 90 chickens died and 910 others were culled. Also on Wednesday, in southern Ben Tre province bird flu was detected in 360 ducks in Hoa Loc and Phuoc Hanh communes and all the ducks were killed.
During the first 12 days of this year, bird flu outbreaks occurred in 74 communes in 34 districts of 10 southern provinces and 36,500 chickens, 45,000 ducks and 49,500 quails were killed. <<
The above descriptions appear to provide additional evidence for asymptomatic ducks. For the chickens the low number that died before culling was mentioned. However, for the ducks in Hoa Loc and Phuoc Hanh there were 360 positives. There is no mention of ducks dying, and it's not clear if the comment that all the ducks were killed includes any untested ducks or it indicates that all 360 ducks tested were positive and killed. Testing 360 ducks seems like a high number, but may reflect the fact that the ducks appear healthy and the only way to detect the H5N1 is to test.
This reflects the concern in the WHO warning indicating that the same H5N1 that kills people in Vietnam and Thailand doesn't cause symptoms in ducks, is present at high concentrations in feces, and is unusually stable. This of course is a dangerous combination because it maintains a high reservoir of virus that is lethal in humans and can recombine to expand its host range. Moreover, the feces can be spread far and wide because the ducks are healthy.
.
Media link