In the last few years, a scourge from the Middle East has posed a biological threat to North American well-being--mosquitoes carrying the West Nile virus.
First identified in Egypt in the 1950s, the West Nile virus originates in birds. Mosquitoes contract the disease when they feed on infected birds. After circulating in the mosquitoes' blood for several days, the virus then lodges in the salivary glands. When an infected mosquito bites a human or other animal, the virus passes into the bitten creature's system, where it rapidly multiplies.
At its most mild, the virus can cause West Nile fever, a relatively harmless disease causing flu-like symptoms for several days. More serious consequences include encephalitis--inflammation of the brain--and meningitis--swelling of the membrane surrounding the brain and spinal cord. Although encephalitis and meningitis are not necessarily deadly, they require immediate medical treatment.
West Nile virus first invaded US shores on the East Coast some time in 1999. With the approach of summer, overwintering mosquitoes in New York City caused an outbreak of West Nile-related symptoms. The virus has since spread throughout the country, infecting and even killing people in several states. Symptoms of severe infection include headache, high fever, stupor, disorientation, tremors, and paralysis.
Although there is currently no definitive treatment, studies to develop a vaccine are underway. Several existing drugs, such as those used to treat hepatitis C, may prove effective against West Nile virus as well.