2005 - West Nile Virus

Table 1. West Nile Virus Cases by Race and Sex, Indiana, 2005

  2005 2001-2005
Cases Rate* Cases
Total 23 0.37 378
Deaths 1   16
Race
   White 17 0.31 291
   Black 1 0.18 17
   Other 0 0 2
   Not Reported 5 - 68
Sex
   Male 13 0.42 192
   Female 9 0.28 185
   Not Reported 1 - 1
*Rate per 100,000 population based on the U.S. Census Bureau’s population data as of July 1, 2005

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 2005, Indiana was one of 43 states, including Washington, D.C., to report human WNV cases. Nationally in 2005, there were 3,000 human cases with 119 deaths. Indiana had 23 reported cases with 1 death.

In 2005, the 23 reported cases of WNV in Indiana represented a rate of less than 1 case per 100,000 population (Table 1). In 2005, the initial case had an onset of illness date starting in late May, followed by a nine-week period in June, July, and August without any reported cases (Figure 1). Reported cases reoccurred with onset dates in mid August-mid September when most cases of WNV occurred. No cases were reported in late September-mid October. The last reported case occurred in late October. Eighty-seven percent of reported cases were in individuals aged 40 years and older (Figure 2).

Ten Indiana counties reported human West Nile virus cases in 2005. However, only Lake County had five or more reported cases, for an incidence rate of 1.8 cases 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:
http://www.IN.gov/isdh/healthinfo/westnile/index.htm
http://www.cdc.gov/ncidod/dvbid/westnile/index.htm