Not everyone who is bitten by an infected mosquito will show symptoms of the virus.
Mosquitoes collected from a trap in Mitchell have tested positive for West Nile Virus, the Perth District Health Unit says.
Three types of mosquitoes tested positive for West Nile virus at a Wethersfield testing site on Goff Road, officials said.
On August 3, the Iowa Public Health Department reported the state's first death from West Nile in 2018 was an 81-year-old man who lived in central Iowa.
"Positive and suspected West Nile cases are a reminder that preventative measures are important", said Dr. Faisal Khan, director of the department.More news: Michael Jordan supports LeBron James after Donald Trump tweet
The Health Unit is urging the public to take steps to prevent mosquito bites.
Minimize time spent outdoors, especially at dawn and dusk when mosquitoes are most active. The most common symptoms of the virus are fever, headaches or physical weakness.
Last year, 26 people contracted the virus and two died in Dallas County.
DCHHS recommends that Dallas County residents use an insect repellent containing DEET whenever they go outside, and that they dress in long, loose and light-colored clothing.