Some Flu Viruses Resist Drugs
Japanese Scientists Find Flu Virus That Resists Tamiflu, Relenza
April 3, 2007 -- Some flu viruses appear to resist the antiviral flu drugs
Tamiflu and Relenza, report Japanese researchers.
They included Shuji Hatakeyama, MD, PhD, a virus expert at the University of
Hatakeyama and colleagues had previously noted cases of influenza type A
that resisted Tamiflu. Now, they note cases of influenza type B that show
reduced sensitivity to Tamiflu and Relenza.
Hatakeyama's team studied flu viruses from a Japanese epidemic of influenza
type B from 2004 to 2005.
The flu specimens came from patients including 74 children who took Tamiflu
for five days, 282 untreated children, and 66 untreated adults.
One of the children who took Tamiflu had influenza type B that resisted
Tamiflu and Relenza, according to the researchers' lab tests.
Seven untreated patients had influenza type B that resisted Tamiflu and
Relenza, the study shows.
The drug-resistant flu had the same symptoms and duration as normal flu.
Drug-resistant flu likely spread through the community or among siblings,
note the researchers.
Drug resistance in influenza type B seems to be rarer than drug resistance
in influenza type A but requires "continued close monitoring," write
Hatakeyama and colleagues.
Experts who wrote a journal editorial agree that drug-resistant flu should
be watched closely.
The news about drug-resistant flu "is not good," states the
editorial. But "an effective response to this news can help contend with
the new challenges of influenza," write the editorialists.
They included Anne Moscona, MD, of the pediatrics, microbiology, and
immunology departments at Weill Medical College of New York's Cornell
The study and editorial appear in The Journal of the American Medical
Tamiflu is made by Roche Laboratories. Relenza is made by GlaxoSmithKline.
Both are WebMD sponsors.
In the journal, the editorialists note financial ties to drug companies
including Roche and GlaxoSmithKline. The Japanese researchers report ties to
other drug companies, but not Roche or GlaxoSmithKline.