The isolated virus was sent to the CDC, and on Sept 27 was announced as being 92 percent homologous with the West Nile virus. In October, after the virus s DNA was decoded, it was found to be the actual West Nile virus, not a strain or mutation. What is known is the virus is passed from host birds to humans, horses, and other animals by mosquitoes, and, in Asia and Africa, ticks can be carriers. Infected people and horses cannot spread the virus, and there is no evidence it can be contracted by handling dead or infected birds, although wearing gloves is advisable when doing so. In humans, this type of encephalitis causes an infection of the brain, known as West Nile fever, with symptoms of head and body aches, swollen lymph glands, high fever, and sometimes a rash.
Death can occur in the elderly, children, and people with weak immune systems.
Given the concentration of bird deaths and the fact that New York City is the only place reporting human fatalities, New York state appears to be the epicenter of the outbreak. There, at least 56 people have tested positive for the West Nile virus. But the infection is assumed to be widespread, with an indeterminable number of people, birds, and horses developing only subclinical infections. Mosquitoes carrying the virus have been found in Connecticut, New Jersey, and New York. The speed at which the virus was isolated and identified is surprising, said Dr. McNamara, considering it was new to the Western Hemisphere.