SMALLPOX is one of the biggest killers in history. But now we have it at our
mercy, with the virus apparently surviving in only two labs, in the US and
Russia. So why, instead of delivering the promised coup de grâce, did the
World Health Organization last week vote to postpone its destruction?
The WHO says it is to allow research to continue. But as recently as last
October, D. A. Henderson, who led the smallpox eradication campaign, argued that
the last official stocks of virus should be destroyed. The live virus is useless
for testing potential new drugs or vaccines, he wrote, as it only infects
people, and people no longer get smallpox.
So what’s changed? The answer, 91av has learned, is that
Peter Jahrling’s team at the US Army Medical Research Institute for Infectious
Diseases at Fort Detrick, Maryland, has finally managed to infect a handful of
cynomolgus macaques with smallpox. They do not yet have a perfect animal model
for the disease. But the researchers hope they will soon be able to test new
vaccines, drugs and diagnostic tools for smallpox.
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Such progress helped the US persuade the WHO’s executive council to vote to
postpone destruction. Not that the US would have destroyed its stock even if the
vote had gone the other way. This November, after the 11 September attacks and
the anthrax scares, US Secretary of Health Tommy Thompson announced that the US
would hang on to its stocks “until adequate medical tools are available to
counter any future outbreak of this disease”.
Of course, if the official stocks really were all that’s left of the virus,
there would be no need for any defences once they were destroyed. After smallpox
was officially eradicated in 1980, the WHO asked all countries to destroy their
samples or send them to the official repositories in the US and Russia. It then
planned to destroy these stocks.
But in 1999, the US convinced WHO members to put off destruction until 2002,
amid rising fears that other, clandestine stocks might be used as weapons,
meaning live virus was needed for defensive research.
“The evidence that anyone else has the virus is circumstantial,” says
Jonathan Tucker of the Monterey Institute of International Studies.
Nevertheless, it is “highly likely”, says Alan Zelicoff of Sandia National
Laboratories in New Mexico. “It is not credible that all nations would give up
their stocks at a UN request,” he says.
Antibodies in soldiers defecting from North Korea reveal recent vaccination
against smallpox—probably, says Zelicoff, because North Korea has a
smallpox weapon. Iraq is also implicated. And not all of the 100 tonnes of virus
the Soviets weaponised per year in the 1980s may have been destroyed.
While the existing vaccine is effective, says David Heymann, head of
infectious diseases at the WHO, it is a live virus related to smallpox with rare
but potentially fatal side effects. And it can make people with impaired
immunity seriously ill. But you can only truly test a replacement for it against
real smallpox virus.
Enter the macaques. But there are problems. So far the animals only get sick
after very large doses of virus, which makes testing vaccines difficult as
enough bugs can defeat any vaccine. And health officials are looking for a drug
that works after symptoms start—unlike cidofovir, the only known
anti-smallpox drug. But most infected macaques die before developing full-blown
symptoms like those in humans, making tests difficult.
The system merely needs development, says Heymann. Whatever the fortunes of
the team at USAMRIID, political pressures in the US are likely to ensure that
this research will continue. Ironically, it will only be a success if it is
never used.