佳能m6电子取景器:求bird flu 的传播途径 （英文）

Bird Flu Spreads in Several Asian Countries

Katherine Maria

The United Nations health agency has confirmed a fourth bird flu death in Vietnam, and says an increased number of patients are seeking treatment for flu-like symptoms in the country's capital. Bird flu has been spreading rapidly among chickens in several Asian countries.

The World Health Organization says all four confirmed cases of bird flu in humans in Vietnam have been fatal. On Saturday the agency confirmed that the H5N1, or bird flu, virus, was found in samples taken from a five-year-old boy who died January 8.

Bob Dietz is the spokesman for a team of WHO experts investigating the outbreak in Vietnam.

"We do have one more confirmed case of H5N1," he said. "This was confirmed using lab results from within Vietnam."

Bird flu has been detected in poultry farms across Vietnam, Taiwan, Japan and South Korea, and millions of chickens have died or been killed in recent days.

But all reports of confirmed and suspected cases in humans have been concentrated in Vietnam, where health officials and doctors have reported a steady increase in suspected cases each day.

Mr. Dietz says there is also a noticeable rise in the number of people seeking treatment for flu-like symptoms in two Hanoi hospitals.

"We are seeing an increased number of respiratory illness cases," said Bob Dietz. "We don't known whether that's because there is more respiratory illness, or it's because cases are being referred to these two large significant hospitals."

The first three confirmed cases were discovered in Hanoi, but the latest victim lived about 100 kilometers south of the capital city in Nam Dinh province.

Mr. Dietz says millions of chickens in Vietnam alone have been slaughtered in efforts to contain the disease's spread.

The first known cases of bird flu in humans were reported in 1997 in Hong Kong. Six of the 18 people infected then died of the disease.

U.N. scientists say the bird flu virus currently affecting Vietnam has not begun to spread between humans. They suggest the victims caught the disease directly from chickens.

The emergence of bird flu in the region comes as health experts in China prepare for a fresh outbreak of Severe Acute Respiratory Syndrome in the country's south.

There, three people have been confirmed to have SARS, but experts are unsure how they caught the disease. Unlike bird flu, SARS can spread between people who are in close and sustained contact.

拜托你说清楚，我在回答，好吗

Bird flu (also known as avian influenza, avian flu, influenzavirus A, type A flu, or genus A flu) is a type of influenza virus that is hosted by birds, but may infect several species of mammals. It was first identified in Italy in the early 1900s and is now known to exist worldwide.

H5N1 is a highly pathogenic strain of bird flu. The first known appearance of this type of influenza in humans was in Hong Kong during 1997. The infection of humans coincided with an epidemic of avian influenza, caused by the same strain, in Hong Kong’s poultry population. The outbreak was stopped by the killing of the entire domestic poultry population within the territory. The name H5N1 refers to the subtypes of surface antigens present on the virus: hemagglutinin type 5 and neuraminidase type 1. As of November 1, 2005, 122 cases of infections in humans, resulting in 62 deaths, have been confirmed outside of China. Thirteen countries across Asia and Europe have been affected. Additionally, more than 120 million birds have died from infection or been killed to prevent further infections.

Normally, avian flu viruses are transported worldwide in the intestines of wild birds, and are non-lethal. However, this variant has mutated into the most lethal strain of avian influenza ever recorded. Such mutations are natural and have happened in the past, as in the influenza pandemic caused by the 1918 Spanish flu, a variant of H1N1. Infected birds pass on H5N1 through their saliva, nasal secretions, and feces. Other birds may pick up the virus through direct contact with these excretions or when they have contact with surfaces contaminated with this material. Because migratory birds are among the carriers of the H5N1 virus it may spread to all parts of the world. Past outbreaks of avian flu have often originated in crowded conditions in southeast and east Asia, where humans, pigs, and poultry live in close quarters. In these conditions a virus can mutate into a form that more easily infects humans.

呵呵