Jan 22, 2004 (CIDRAP News) – The World Health Organization (WHO) warned today that the avian influenza outbreaks and related human cases in East Asia may get worse, while worries about a possible outbreak mounted in Thailand.
The WHO called the simultaneous outbreaks of highly pathogenic H5N1 influenza in poultry in Vietnam, South Korea, and Japan "historically unprecedented." Because of the scale of the outbreaks and because wild birds can spread the fatal infection to domestic flocks, "The present situation may grow worse," the agency said.
The WHO also said initial studies of H5N1 viruses from humans and poultry in Vietnam indicate they are significantly different from H5N1 viruses obtained during outbreaks in Hong Kong in 1997 and 2003. But officials didn't suggest what the differences might mean.
In Thailand, test results on three people with pneumonia-like symptoms were being awaited, while government officials continued to insist that a disease that has killed millions of chickens there is not influenza.
The three people were among 17 pneumonia patients who were tested for avian flu because they had contact with chickens, according to an online report today by the Bangkok Post. The other 14 were found to have bacterial infections. One of the three, a butcher, became ill Jan 7 after the death of 70 chickens on his farm, the report said.
Thai Prime Minister Nirun Phitakwatchara denied reports that one of the other two patients, a boy, had tested positive for the disease, according to the Associated Press (AP). But a Thai senator said the boy had the disease and accused the government of a cover-up.
The AP report said about 6 million chickens in central Thailand have died or been slaughtered because of a disease. The government has insisted that the disease is not influenza but rather a combination of fowl cholera and other respiratory diseases.
In Hong Kong yesterday, tests showed that a dead peregrine falcon carried the H5N1 virus, according to Xinhua, China's state-controlled news agency. Inspectors found no signs of illness at two chicken farms near where the falcon was found, the report said. Hong Kong officials promised to step up surveillance of poultry and wild birds.
Vietnamese officials acknowledged yesterday that nearly 900,000 chickens that might have been exposed to the flu virus had been sold to the public, according to AP reports. The chickens came from two hard-hit provinces in southern Vietnam and were sold in early January, before a mass poultry slaughter was carried out.
A report by the state-controlled Vietnam News Agency said the country has had 30 suspected human cases of avian flu, in addition to the 5 fatal cases that were previously confirmed as H5N1 infections. The 30 suspected cases include nine other fatal ones.
The report said Hanoi's National Hospital for Paediatrics has 10 patients, ranging in age from 1 to 14, who may have avian flu.
The WHO fears that the H5N1 virus could infect a human carrier of another flu virus and combine with that virus to create a highly infectious new one, possibly launching a flu pandemic. The agency said today, "Rapid elimination of the H5N1 virus in bird populations should be given high priority as a matter of international public health importance."
Without commenting on the situation in Thailand, the WHO statement said, "The H5N1 strain may be more widely established in bird populations and in the environment in this part of the world than presently appreciated." Birds can shed large amounts of the virus in their droppings, and it can survive a long time in the tissue and feces of diseased birds and in water, especially in low temperatures, the agency said.
Contact with poultry kept in live markets was the cause of H5N1 infection for 17 of 18 people in Hong Kong's outbreak in 1997, the WHO said. The sacrifice of poultry flocks not only helps contain avian outbreaks but also reduces human exposure. But limiting human exposure is likely to be difficult in the current situation because of the large number of backyard chicken flocks in rural areas, the agency said.
Infection control during poultry slaughter operations is important, the WHO added. "Culling operations can place large numbers of workers at high risk of brief but intensive exposure to the virus." The agency promised to provide safety guidelines for culling operations soon.
The US Centers for Disease Control and Prevention, in information on its Web site, this week advised travelers to Vietnam to avoid contact with animals in live markets and any surfaces that appear contaminated with feces of poultry or other animals.
Jan 22 WHO statement
CDC information about avian flu outbreak in Vietnam