In New York City, several people fall ill with a mysterious virus. Doctors believe that the virus is spread by mosquitoes. The Center for Disease Control eventually identifies the illness as West Nile virus, a virus spread by mosquitoes to humans and birds. Also in the program, a Navajo community in New Mexico is stricken with a virus characterized by fluid in the lungs. After an investigation, the CDC finds the virus to be the hantavirus, a pathogen spread by rodents.
