Warning Over Smallpox Relative

Wednesday, 17 April, 2002, 18:01 GMT 19:01 UK
The virus is comon in camels

Scientists have discovered that virus isolated from camels is a much closer relative to the smallpox virus than had been thought.

The results suggest that camelpox could evolve to cause disease in humans.

It could be that only a small set of changes would be necessary for camelpox virus to infect people

Dr Geoffrey Smith It also raises fears that it could be used as a biological weapon.

New Scientist magazine reports that Dr Geoffrey Smith, of Imperial College in London, has closely studied a strain of camelpox virus isolated from camels in Iran in 1970.

Dr Smith told the magazine: "It was surprising how close these two viruses were."

"It could be that only a small set of changes would be necessary for camelpox virus to infect people."

The viruses that cause smallpox and camelpox are both members of the orthopox family.

Research has shown that the genetic make-up of the viruses is remarkably similar - even in the outer regions which usually vary between species.

Filling a gap

Dr Lev Sandakhchiev, head of Vector, the Russian laboratory that holds one of the two remaining official stocks of smallpox virus said it was inevitable that another virus would evolve to fill the gap left by the deadly bug.

However, D.A. Henderson, who led the global campaign to eradicate smallpox, is sceptical that camelpox will one day pose a risk to humans.

The virus has so far shown little interest in humans, and camel handlers appear unharmed despite prolonged exposure.

Camelpox is endemic among the world's 20 million camels and there is no vaccine.

But it is possible that camel handlers show no symptoms of infection only because they are immunised by exposure at an early age.

Adults who are new to camels, and lack immunity to any orthopoxes now that smallpox vaccination has stopped, might provide the virus with novel opportunities.

Dr David Brown, of the Public Health Laboratory Service, told BBC News Online: "It is a theoretical possibility, however it has been 20 years since smallpox was eradicated and vaccination stopped and there is no evidence that camelpox has filled the niche during this time."

In 1995, the Iraqi government admitted to UN weapons inspectors that its weapons scientists were working with camelpox.

They claimed they wanted to use it as a weapon to which Iraqis, who are used to camels, would be immune, while foreign troops would not.

http://news.bbc.co.uk/hi/english/health/newsid_1934000/1934692.stm