West Nile here to stay; treatments sought

The neurological complications from the virus have prompted a flurry of research to identify vaccines.

By Susan J. Landers, AMNews staff. Nov. 8, 2004.

Washington -- West Nile virus has assumed its place as an infectious disease with which the nation must reckon -- only five years after its arrival was first noted in New York City.

Transmitted primarily by mosquitoes and carried by wild birds, the virus has swept across the country, causing the deaths of more than 600 people and triggering serious neurological conditions in many others. The virus has most recently been linked to cases of acute flaccid paralysis due to the development of West Nile poliomyelitis.

Closely observed during its relentless march west to California, much has been learned about the virus, but there is still much to discover.

The virus was quickly identified as a member of the flavivirus family, which includes viruses that cause yellow fever, dengue fever and St. Louis encephalitis. Most people infected by West Nile experience no symptoms, and many others experience fairly mild symptoms of fever, headache and sometimes swollen glands and a mild rash.

However, among the 10,000 cases of the illness reported last year, there were 761 cases of such neuroinvasive diseases as meningitis and encephalitis and 503 cases with additional serious clinical outcomes, such as acute flaccid paralysis.

"It's still unknown what the natural history of this virus will be," said Steven Opal, MD, professor of medicine at Brown University School of Medicine's infectious disease division. So far the virus has a very different epidemiology from that in Africa, where it has been recognized for decades.