The number of West Nile virus (WNV) cases soared this year to 95 as of Oct. 26, the second highest since 2003 when 147 human cases were reported to the Iowa Department of Public Health (IDPH). Included in the count of 2018 cases are five Iowa deaths, according to the CDC. The average numbers of cases and deaths in Iowa for the past three years (2015-2017) was 21 cases and one death.

The State Hygienic Laboratory performs antibody detection for West Nile virus using enzyme immunoassay methods.

The culex species of mosquitoes, which tend to come out in late summer and early fall, are the most likely carriers of the virus.

“School has started, Halloween is just around the corner, and some people are even thinking about the holidays, but mosquitoes still are thriving and biting” said IDPH Deputy Epidemiologist, Dr. Ann Garvey. “West Nile virus activity will continue until the state's first hard frost, regardless of the date on the calendar."

In a joint effort with the State Hygienic Laboratory, the Iowa State University Department of Entomology, the Iowa Department of Agriculture and Land Stewardship, and several local health departments, IDPH operates a number of programs that have allowed Iowa to monitor West Nile virus activity in sentinel chickens, mosquitoes, horses, and humans.

Most people who are infected with WNV may not experience any signs or symptoms. The other 20 percent may have a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea or rash. Though most people who suffer these symptoms recover completely from West Nile virus, they may suffer fatigue and weakness for weeks or months.

About one in 150 people infected develop a severe illness such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes that surround the brain and spinal cord). People 60 years and older, and those with certain medical conditions are most at risk.

West Nile virus has been in the United States since 1999, and in Iowa since 2002. Mosquitos that bite infected birds may transmit the virus to people, horses and other mammals.