West Nile virus hits earlier this season and expands its geographic range

Government agencies work together to track the mosquito-borne illness.

By Stephanie Stapleton, AMNews staff. Aug. 13, 2001.

On July 15, the summer's first human infection of West Nile virus was reported in Florida when a 73-year-old man was hospitalized with encephalitis.

The onset of his illness is a sentinel event for a variety of reasons. First, it is the earliest human onset reported since the illness' 1999 recognition in the United States. It also occurred at a point further south than past infections -- tracking the virus' ever-expanding reach.

West Nile virus' travels to date are the subject of a July 27 MMWR report detailing activity between Jan. 1 and July 25. Surveillance of the virus is being conducted by the Centers for Disease Control and Prevention, the U.S. Geologic Survey and the Dept. of Agriculture.

"Anywhere the virus has appeared, it has reappeared," said Stephen Ostroff, MD, a CDC medical epidemiologist who participated in a July 26 briefing on the report. Thus, he added, the data regarding where West Nile has been identified in 2001 are "really not entirely unexpected."

After the virus' initial identification in New York, there was an expectation that it would move into different areas -- particularly as birds followed their migratory paths down the Atlantic coast. "That's essentially what happened," Dr. Ostroff said. The part that is less predictable is specifically where and when.

Keeping tabs on patterns requires a coordinated effort by the government. An enhanced human and animal surveillance system involving the federal agencies and state and local health departments was designed in 2000 to identify areas at increased risk for human infection. [...]