WASHINGTON - 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.
