Chickens infected with bird flu in Vietnam are not always getting sick, allowing the virus to spread among poultry without being detected, the UN Food and Agriculture Organisation said Monday June 27.
Ducks had previously been asymptotic to the H5N1 strain of the virus, but chickens that suddenly became ill and died have in the past served as indicators that the virus had infected poultry stocks. Now chickens that appear healthy can also be carrying the disease, said Anton Rychener, head of the FAO in Hanoi.
Lab results overseas and in Vietnam also show that the genetic makeup of the virus has changed slightly among poultry, he said.
“We know it has changed,” he said. “It has become less virulent and is more present in humans.”
Last month during a meeting in Manila, the World Health Organisation also reported changes in the virus, warning about the potential for the disease to alter and spread easily from person-to-person, possibly sparking a global pandemic that kills millions.
Bird flu has killed 38 people in Vietnam, 12 in Thailand and four from Cambodia since it ravaged poultry farms across Asia in late 2003.