Researcher sounds new virus alarm

Sharon Hill
5 November 2004
It's only a matter of time before a mosquito-borne pathogen that's worse than the West Nile virus reaches North America with the potential to kill people and devastate the livestock industry, says a U.S. research entomologist.

Michael Turrell is pushing for more research on what types of mosquitoes could carry the Rift Valley fever virus before it spreads from Africa and Egypt.

"Rift is a much worse virus than West Nile," he said Thursday from the U.S. Army Medical Research Institute of Infectious Diseases in Fort Detrick, Md. "My personal belief is it will get here. Five years? I don't know. Thirty years? I would not be surprised."

Turrell will present the information next week in Florida at a meeting of the American Society of Tropical Medicine and Hygiene. Without better information, it's impossible to plan effective spraying programs, he said, adding it'll be too late once the virus makes the jump.

The virus could be transported by an infected tourist or mosquitoes hitching a ride on an airplane. There is no effective human or veterinary vaccine for use in North and South America.

However, Dr. Harvey Artsob, director of zoonotic diseases with the Public Health Agency of Canada in Winnipeg, said: "it's not high on our radar screen as a level of concern because the virus has to get here and that's a bit of a daunting challenge." There are mosquitoes that could spread the virus in North America, but it isn't known if Rift Valley could survive the winter, he said.

Unlike West Nile, which may not show symptoms in infected people, almost everyone who has Rift Valley fever has flu-like symptoms and one per cent die, Turrell said.

The virus is spread by a bite from an infected mosquito or contact with blood, such as someone delivering an aborted calf or slaughtering an animal.

Infected people may get encephalitis and a severe bleeding disease that causes blood to ooze out of the eyes and nose of a dying patient. People who recover may lose sight because the disease affects the optic nerve.

If the virus arrived in North America, Turrell said, it could economically devastate livestock industries as animals die and borders are closed to exports. The first sign of an epidemic would likely be miscarriages in livestock such as cattle, sheep and goats.

It's not known if the virus would affect other animals, he said.

Calgary Herald
November 5, 2004