Study finds drug-resistant flu virus in Japan
Pastor Dale Morgan
Study finds drug-resistant flu virus in Japan*
03 Apr 2007 20:00:07 GMT
Source: Reuters
CHICAGO, April 3 (Reuters) - Type B flu viruses, which usually cause
smaller epidemics than type A, developed partial resistance to two
front-line anti-viral drugs used to combat seasonal influenza, according
to a study published on Tuesday.
While there has been evidence of some type A flu viruses developing a
resistance to anti-viral drugs, researchers at the University of Tokyo
said until their study there has been only limited information involving
type B.
The research involved Tamiflu, an antiviral drug made by Roche <ROG.V>
and Gilead Sciences <GILD.O>, and Relenza, made by GlaxoSmithKline
<GSK.L><GSK.N> and Biota Holdings <BTA.AX>, and known generically as
zanamivir.
Tamiflu, also known as oseltamivir, is the first choice against both
seasonal flu and the H5N1 avian influenza.
The findings come from Japan where both drugs to prevent and treat
seasonal flu are used more extensively than anywhere else in the world.
The study involved an influenza B virus outbreak in the winter of
2004-2005 that caused a widespread epidemic.
Writing in this week's journal of the American Medical Association,
researchers said they collected flu B virus samples from 74 children
before and after Tamiflu use and from 348 influenza patients -- also
mostly children -- who were not treated with the drug.
They said they found a virus with reduced drug sensitivity in one of the
74 children who had received Tamiflu. In addition, seven of the 422
influenza B viruses isolated from untreated patients were found to have
reduced sensitivity to Relenza, Tamiflu, or both.
Drug resistant flu viruses present a risk because the mutations can make
current drugs ineffective for both seasonal flu and a potentially
devastating bird flu epidemic.
An editorial in the same issue commenting on the study said it raised
more questions than it answered.
But, it said, "some facts are strikingly clear. Influenza B mutants with
reduced sensitivity to (anti-viral drugs) are circulating, and these
viruses can cause infections with no difference in duration of symptoms...
"Contrary to what had been hoped until now, some resistant variants are
vigorous pathogens. Whether these viruses arise by spontaneous mutation
... or whether they are transmitted within families or acquired from the
community, the resistant variants may be here to stay," the editorial
added.