The Iowa Department of Public Health (IDPH) on Thursday announced seven cases of West Nile virus have been confirmed in Iowa: one case each in Buchanan, Clay, Crawford, Monona, Plymouth, Sioux and Woodbury counties. Additional cases are being investigated in Sac and Shelby counties. Two of the confirmed cases were hospitalized, but are now recovering at home.

Culex mosquito
Culex quinquefasciatus

In addition to the human cases of West Nile virus, four mosquito pools have tested positive for the virus: two pools in Story County, one from Polk County, and one from Woodbury County. Mosquito pools are a method researchers use to see if insects in an area are carrying the West Nile virus, which can then be transmitted to humans through a bite. A horse in Johnson County tested positive for West Nile virus.

“We are now seeing either confirmed human cases, animal cases, or positive mosquito pools across a large area of the state,” said IDPH Medical Director, Dr. Patricia Quinlisk. “This is not unexpected as late summer and autumn are the times when mosquitoes carrying West Nile virus are most likely to be circulating. This is why it is important to continue to use insect repellent when outdoors, and to take other protective and preventive measures.”

Approximately 20 percent of people infected with West Nile virus will have mild to moderate symptoms such as fever, headache, body aches and vomiting. Less than one percent of people infected become seriously ill and rarely someone dies. Since West Nile first appeared in Iowa in 2002, it has been found in every county in Iowa, either in humans, horses, or birds. In 2013, there were 44 human cases of West Nile virus and zero deaths.