Why Bird Flu Stories Aren't All Bad
NewsBy MARK HENDERSON
It is now five years since the present outbreak of H5N1
avian flu first infected people. Though 379 people have
since contracted the virus, of whom 239 have died, it
has yet to start a pandemic.
As its name suggests, bird flu remains predominantly
an avian disease. While it is very dangerous to
humans who catch it, this has happened only rarely,
after close contact with infected birds.
This week, however, brought some alarming news.
Writing in The Lancet, a Chinese medical team
confirmed that a 52-year-old man who contracted
H5N1 in Jiangsu province last December almost
certainly caught it from his 24-year-old son, who died.
It is the best-documented case of human-to-human
transmission to date.
That is important because, if this virus is going to start
a pandemic, it must first acquire the ability to move
readily from person to person. Not enough people are
ever going to catch it from birds to constitute a global
threat. The Chinese case, like a previous suspected
human-to-human incident in Thailand, has thus
raised fears that H5N1 might be mutating in worrying
fashion, and it was duly reported around the world.
The details of the Lancet study, however, are less
troubling than they at first appear. This investigation of
this cluster of infections, indeed, is somewhat
reassuring because of what it shows has not
happened.
First, genetic analysis of virus samples recovered
from both men has revealed no substantial mutations
from the standard circulating strain. It does not seem
to be evolving, yet at least, into a humanised version
that can easily set up home in the human respiratory
tract.
Furthermore, the scientists found that 91 people had
close contact with one or both of the infected men, and
yet the virus was passed on only once. This is more
good news, confirming that the existing strain is poorly-
adapted to people. The father seems to have been
extremely unlucky. The case is also encouraging in
that it has offered two new leads for medical research,
which could prove important in tracking the threat from
bird flu and establishing how it is best treated.
The way the virus was passed on only from son to
father may reflect their intimate relationship, which
probably involved closer contact than with the other
people who were exposed. But it could also indicate
that they shared a genetic susceptibility to H5N1.
While this is far from certain, if it is confirmed it would
provide an important clue that could assist efforts to
design drugs and vaccines against it.
Another important detail is that the father recovered,
after treatment with antivirals and blood plasma from a
woman who'd been vaccinated against H5N1 in a
clinical trial. The apparent success of this therapy
could be significant, as it has been suggested as an
emergency means of containing a pandemic in the
absence of a vaccine.
Perhaps the most positive aspect of these cases,
however, is that we have learnt about them in such
detail at all. Not long ago, few international scientists
would have expected Chinese officials to have
released data about the Jiangsu cluster so freely. The
country had a reputation for secrecy about H5N1
cases, and for its reluctance to share virus samples
and information.
China now seems to have had a change of heart: the
Jiangsu virus was analysed in collaboration with the
US Centers for Disease Control, and the results have
been published in The Lancet, a journal with wide
circulation.
That can only be a welcome development: the hazards
posed by avian flu are global and efforts to understand
the virus and develop counter-measures will benefit
from such openness. H5N1 flu might not yet have
triggered a pandemic, and this case does not suggest
it is about to. But the virus hasn't gone away, and
international surveillance and co-operation is going to
be critical to managing its future threat.
Mark Henderson is the Science Editor of The Times
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