Bird flu may transmit more easily than previously believed

[Guest guest]

according to a new study published in the New England Journal of Medicine:

http://www.reuters.com/article/healthNews/idUSN1616209020080117

WASHINGTON (Reuters) - The H5N1 bird flu virus may sometimes stick to

surfaces or get kicked up in fertilizer dust to infect people,

according to a World Health Organization report published on Wednesday.

The WHO team reviewed all known human cases of avian influenza, which

has infected 350 people in 14 countries and killed 217 of them since

2003, and found that 25 percent of cases have no explanation.

Most are passed directly from bird to people, they noted in their

report, published in the New England Journal of Medicine. And very

rarely one person can infect another -- always close relatives via

intimate physical contact.

" In one quarter or more of patients with influenza A (H5N1) virus

infection, the source of exposure is unclear, and environment-to-human

transmission remains possible, " the researchers, led by WHO's Dr.

Frederick Hayden, wrote.

" For some patients, the only identified risk factor was visiting a

live-poultry market. "

It could be that small particles of virus-contaminated fluid stuck to

surfaces, they said. Or perhaps fertilizer made from infected bird

feces somehow carried the virus into people's noses or mouths.

" It is unknown whether influenza A (H5N1) virus infection can begin in

the human gastrointestinal tract, " they wrote.

" In several patients, diarrheal disease preceded respiratory symptoms,

and virus has been detected in feces. "

Government and health officials have stressed that well-cooked chicken

cannot infect people. " Drinking potable water and eating properly

cooked foods are not considered to be risk factors, but ingestion of

virus-contaminated products or swimming or bathing in

virus-contaminated water might pose a risk, " the WHO team of bird flu

experts noted.

ENDEMIC IN BIRDS

H5N1 is considered entrenched in parts of Asia, including Indonesia,

Africa and the Middle East. It pops up frequently in Europe and has

prompted the slaughter of hundreds of millions of chickens.

The researchers noted that people only rarely become infected. The

fear is that the virus will mutate into a strain that passes easily

from one person to another, setting off a pandemic that could kill

millions of people in the space of a few months.

" After exposure to infected poultry, the incubation period generally

appears to be 7 days or less, and in many cases this period is 2 to 5

days, " the WHO team wrote.

" In clusters in which limited, human-to-human transmission has

probably occurred, the incubation period appears to be approximately 3

to 5 days, although in one cluster it was estimated to be 8 to 9 days. "

It usually causes severe pneumonia and tests suggest that it rarely or

never infects people without causing symptoms.

Avian flu kills on average within nine to 10 days and has killed 61

percent of victims.

Quick use of antiviral drugs can save lives, they noted, although some

strains of the virus are more treatable than others with Tamiflu, the

drug of choice to treat influenza. It is made by Roche Holdings AG and

Gilead Sciences under the generic name oseltamivir