By RANDOLPH E. SCHMID
AP Science Writer

WASHINGTON (AP) -- When bird flu infects people, the virus is more
concentrated in the throat than the nose, the opposite of human flu.
This finding may help doctors more quickly diagnose the bird flu in people.

The disease has been linked to the deaths of more than 140 people
worldwide, mostly among Asian farm families who live in close contact to
birds. There have been no reports of infections of people in the United
States.

Health officials have monitored the disease as it moves through poultry
and other animals. The fear is it could mutate into a form that spreads
easily from person to person, a development that officials say could
lead to a global pandemic.

Researchers are studying the disease in an effort to find a way to
prevent or block it and to treat victims.

Menno de Jong of the Oxford University Clinical Research Unit at the
Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam, reports in
Monday's issue of Nature Medicine that people with bird flu had much
higher levels of the virus in their throat than in their nose.

That is important in showing doctors a better way to diagnose the
disease, he said. It is also important that physicians can detect the
virus in diarrhea and other rectal secretions. This is one more way the
disease can spread and shows the need for infection-control measures, de
Jong said in an interview via e-mail.

"Our observations suggest that early recognition and early treatment may
provide the best benefit. Early recognition and diagnosis will pose a
challenge for clinicians," he said.

De Jong and his co-authors studied 18 people infected with bird flu,
which is known as H5N1, and compared them with eight people who had
common human flu viruses.

"Our observations suggest that H5N1 virus replicates to very high levels
- higher than common human flu - in the respiratory system and that
these high levels of virus ignite an overwhelming intense inflammatory
response," he said.

In inflammation, the body's immune system causes blood vessels to allow
chemicals and blood cells to leak into an infected area, designed to
attack the infection, but an over-response can cause harm.

"Extensive damage to the lungs and possibly other organs are likely
caused by both the direct effects of the virus as well as by the intense
inflammatory response to the virus by the infected individual," de Jong
said.

He said the researchers could detect the bird flu virus in the blood of
people who died of the disease, but not in the blood of these who
survived an infection.

"The virus in the bloodstream most likely is picked up during passage of
the blood through the lungs where most virus replication occurs," he said.

"The presence of virus in the bloodstream may be a direct consequence of
high levels of virus in the most important site of infection (lungs) and
reflect an overall high 'bodyburden' of virus in fatal cases," he said.

Dr. Wilbur H. Chen of the University of Maryland School of Medicine in
Baltimore said that researchers are clamoring for more details on how
the bird flu affects humans, and in particular better ways to quickly
diagnose the illness.

Chen, who was not part of de Jong's research team, said it sounds like
the researchers found some useful information.

De Jong's work was funded by the Wellcome Trust.

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On the Net:

Nature Medicine: http://www.nature.com/naturemedicine