West Nile Virus 2004
*Rate per 100,000 population based on the U.S. Census Bureau’s population data as of July 1, 2004
The West Nile virus (WNV) was first identified in Indiana in 2001. In that year, WNV was identified in 47 birds and 1 horse from 7 counties. In 2004, Indiana was one of 40 states, including Washington, D.C., to report human WNV cases. Nationally in 2004, there were 2,359 human cases with 100 deaths. Indiana had 14 reported cases with no deaths.
In 2004, the 14 reported cases of WNV in Indiana represented a rate of less than 1 case per 100,000 population (Table 1). In 2004, the initial cases had onset of illness dates starting in July, followed by a three-week period in July without any reported cases (Figure 1). One reported case occurred in August followed by another three-week period without any reported cases. Reported cases reoccurred with onset dates in early September when most cases of WNV occurred. Reported cases decreased in late September, with the last reported case occurring in late October. Seventy-nine percent of reported cases were in individuals aged 40 years and older (Figure 2).
Ten Indiana counties reported human West Nile virus cases in 2004. However, only Lake County had five or more reported cases, for an incidence rate of 1.0 case per 100,000 population.
West Nile virus is endemic in Indiana, and virus activity will continue to occur during the mosquito breeding season in future years. The extent of activity will depend on the weather, presence of mosquito and bird populations for virus amplification, equine vaccination rates, and human activities to prevent transmission.
You can learn more about West Nile virus by visiting the following Web sites: