An eerie sense of déjà-vu
creeps over Alva Patterson as she watches a clip on the
bird flu in Asia on the news. The death of her sister
in the flu epidemic of 1918 is among the 90-year-old's
earliest memories, and she wonders fearfully if history
will be repeated. People in the know also share Alva's
concern.
The latest depressing news on the
influenza front was published in the August 31 issue
of The Lancet. A survey of young Japanese children
diagnosed with type A influenza found that 18% harboured
viruses resistant to oseltamivir, considered the most
dependable of the new antiviral flu meds.
Dr Yoshihiro Kawaoka of the University
of Tokyo, and colleagues, tested for oseltamivir resistance
in 50 Japanese children, most of whom were under age
three. In nine cases, they detected viruses resistant
to the drug.
Is this new breed of bugs transmissible?
Unfortunately, the study was too small and too short
to fully answer this crucial question. In any case,
it would have been unethical to facilitate the transmission
of drug-resistant disease among children.
"If we are very lucky," commented
Dr Anne Moscona, a virologist at the Mount Sinai School
of Medicine in New York, "[the viruses] may have a growth
disadvantage, or, for other reasons, be less virulent
or transmissible. If resistant variants are transmissible
and pathogenic, then the widespread use of oseltamivir
in a pandemic situation raises concerns."
The statement certainly doesn't
dampen the fear that the avian flu in Asia could develop
into a super-strain. The threat is utterly real according
to Dr Moscona, who wrote a commentary accompanying the
research in The Lancet. "Several quite likely
scenarios can lead to the 2004 avian virus becoming
more transmissible from human being to human being.
If the virulent avian influenza recombines in people
with a human influenza, or recombines in the pigs that
already harbour these human viruses, a terrifyingly
lethal strain will present an immediate pandemic threat
to human beings," she claimed.
The world's flu vaccine development
system offers no guarantees against a lethal and unexpected
mutation of the disease. So the development of neuraminidase
inhibitors like oseltamivir � a drug that has some effect
against the lethal type A H5N1 avian virus � came as
a relief to public health authorities, who have been
assiduously stocking them.
This latest discovery of
bugs that are resistant to this class of antivirals
knocks away the foundations on which our flu defences
are based. If avian flu combines with an oseltamivir-resistant
transmissible virus, concerns about a flu pandemic might
be better described as panic.
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