New
study highlights need for early use of Tamiflu
10 September, 2006
New research conducted among bird-flu victims in
Vietnam shows the H5N1 virus replicates massively before unleashing
a dangerous inflammatory response by the immune system, indicating
that patients should be given antiviral drugs as soon as possible.
Published online Sunday by the journal Nature Medicine,
the study focuses on 18 Vietnamese who caught bird flu in 2004 and
2005, 13 of whom died.
Samples were taken from these patients to assess
the level of H5N1 virus in the throat, and compared with other patients
who had two strains of ordinary human flu.
H5N1 patients had much higher viral loads than
counterparts with the human virus. In addition, high levels of H5N1
also triggered a "dysregulation" of cytokines -- messenger
proteins in the immune system -- which in turn caused inflammation
and worsened the patient's condition.
"The focus of clinical management should be
on preventing this intense cytokine response, by early diagnosis
and effective antiviral treatment," says the paper, lead-authored
by Menno de Jong of the Oxford University Clinical Research Unit
in Ho Chi Minh City, Vietnam.
The antiviral of choice in fighting H5N1 is oseltamivir,
which is made by the Swiss group Roche and commercialised under
the brand Tamiflu.
Tamiflu is not a cure for flu. It brakes replication
of the virus, thereby easing inflammation which is the cause of
most flu symptoms and speeding the time to recovery.
Roche recommends that Tamiflu be administered within
48 hours to treat ordinary seasonal human flu, and says work is
under way to fine tune treatment for bird flu.
Millions of doses of Tamiflu are being stockpiled
by governments and the World Health Organisation in the event of
a global flu pandemic.
Some experts warn against over-reliance on Tamiflu,
fearing that the drug could be of limited use if the H5N1 virus,
at present transmissible from birds to humans, mutates into a form
that could make it easily contagious among humans.
In the Vietnam study, 17 of the 18 cases received
Tamiflu. The drug appears to have had little effect, but probably
because it was administered too late to prevent the cytokine cascade,
the paper said.
