Avian Flu Speads Across Asia

GENEVA, Switzerland, January 16, 2004 (ENS) - Avian influenza, a highly contagious disease of domestic birds such as chickens and ducks, is sweeping Asia and making humans sick too. The disease, which was first identified in Italy more than 100 years ago, occurs worldwide.

Taiwan ordered 20,000 chickens killed Thursday after a strain of bird flu was discovered at a farm on the island. Officials say the slaughter is a precautionary measure.

In Vietnam, in the past week, the authorities have declared 14 cases of severe respiratory disease in Hanoi, and 11 people have died. Three of these cases were confirmed as Avian flu victims.

Vietnam declared an outbreak of Highly Pathogenic Avian Influenza H5N1 in the southern part of the country last week. The Office International des Epizooties (OIE) in Paris, the World Health Organization (WHO) and the UN Food and Agriculture Organization (FAO) were immediately informed.

Vietnam rapidly applied appropriate control measures such as the killing of several hundred thousands of chickens, disinfection, quarantine, control of animal movements, and general surveys.

But despite these measures, the situation continues to give cause for concern, with new outbreaks possible in Vietnam, FAO said.

Avian flu can spread very quickly amongst overcrowded chickens. (Photo courtesy Farm Sanctuary)

There is still no evidence to date of human-to-human transmission, said FAO experts, but they are taking the possibility "very seriously."

The European Commission offered today assistance to the Vietnam Government in dealing with all aspects of the Avian Influenza crisis in the country in response to a World Health Organization appeal for support.

European Health Commissioner David Byrne, on an official visit to the country today, said after his meetings with Vice Prime Minister Vu Khoanm and Vice-Minister of Health Tran Chi Liem, "European experts with outstanding knowledge and expertise are available to travel to Vietnam over the coming days to assist with the investigation into the human and animal health problems."

"Last year the EU was itself hit by a major outbreak of Avian influenza and having gone through that experience I understand fully the challenges facing Vietnam," Byrne said.

In South Korea, officials Wednesday announced the spread of a different strain - H5N1 avian influenza - to an additional farm.

Japan is also experiencing an outbreak in poultry caused by the H5N1 virus. On Wednesday, Dr. Masako Kurimoto, director of the Animal Health and Animal Products Safety Division, Ministry of Agriculture, Forestry and Fisheries, said the disease broke out in Yamaguchi prefecture, but origin of the infection and the way it is spread are unknown.

The farm is under quarantine and no birds can be moved there and or from other farms within a 30 kilometer (20 mile) radius zone around the affected farm.

"The disease seems to have a regional dimension, with South Korea, Vietnam and Japan being affected in a short period of time," FAO said in a statement. The agency will investigate possible links between these outbreaks.

The WHO Global Influenza Network will receive virus and clinical specimens shortly. As a precautionary measure, network laboratories will immediately begin work on the development of a strain that can be used to produce a vaccine.

Recent research has shown that viruses of low disease causing potential can, after circulation for sometimes short periods in a poultry population, mutate into highly pathogenic viruses.

During a 1983–1984 epidemic in the United States, the H5N2 virus initially caused low mortality, but within six months became highly pathogenic, with a death rate approaching 90 percent, WHO says. Control of the outbreak required destruction of more than 17 million birds at a cost of nearly US$65 million.

Avian influenza viruses do not normally infect species other than birds and pigs, according to the World Health Organization. The first documented infection of humans with an avian influenza virus occurred in Hong Kong in 1997, when the H5N1 strain caused severe respiratory disease in 18 humans. Six of these people died. The infection of humans coincided with an epidemic of highly pathogenic avian influenza, caused by the same strain, in Hong Kong’s poultry population.

Extensive investigation of that outbreak determined that close contact with live infected poultry was the source of human infection. Studies at the genetic level further determined that the virus had jumped directly from birds to humans. Limited transmission to health care workers occurred, but did not cause severe disease.

Rapid destruction – within three days – of Hong Kong’s entire poultry population, estimated at around 1.5 million birds, reduced opportunities for further direct transmission to humans, and may have averted a pandemic, WHO says.

That event alarmed public health authorities, as it marked the first time that an avian influenza virus was transmitted directly to humans and caused severe illness with high mortality.

Alarm mounted again in February 2003, when an outbreak of H5N1 avian influenza in Hong Kong caused two cases and one death in members of a family who had recently travelled to southern China.