At least one person in Douglas County has contracted West Nile virus, officials say.

Like other parts of the country, Kansas is seeing an increase in West Nile virus, a potentially deadly disease that is spread by mosquitoes.

So far, 18 cases have been reported, including one in Douglas County. Eleven of the cases have been in Sedgwick County, and the rest are from across the state.

“We usually think of the peak time for West Nile virus cases in Kansas being in August and even in September. So, I think we are definitely going to be seeing more cases,” said Ingrid Garrison, state public health veterinarian for the Kansas Department of Health and Environment.

She said the virus can cause a mild illness with symptoms such as a fever, headache, body aches, nausea and vomiting. For a few — about one in 150 —it can develop into a severe illness with permanent neurological effects. Garrison said Kansas has had nine cases fall into the severe category.

Last year, one Kansan died from the illness.

“That severe disease usually affects people who are older than 50 and people who are already sick with another illness or chronic condition,” she said.

She said it’s important to contact a doctor right away if you have symptoms, which typically develop three to 14 days after being bitten by an infected mosquito.

Garrison said there is no vaccine for humans, so the best way to prevent the disease is to avoid mosquito bites. She recommended using insect repellent with DEET when outdoors and wearing pants and long-sleeved shirts. It’s important to get rid of any standing water in the yard, which can serve as a breeding site for mosquitoes, and it’s important to refresh water in bird baths and pet dishes.

The country is seeing the highest number of West Nile virus cases since the disease was first detected in the United States in 1999. The first case was in New York, then it moved westward. Kansas didn’t see its first case until 2002.

So far this year, 1,118 cases have been reported to the Centers for Disease Control and Prevention, and 41 people have died. About half of the cases have been from Texas.

Garrison said health experts aren’t sure why there has been an uptick in cases this year, and they are worried that people aren’t taking proper precautions because of the hot, dry conditions.

“We just want to make sure that people are aware that even though it’s really dry and people aren’t thinking about mosquitoes that they need to be protecting themselves, and they need to be wearing mosquito repellent,” she said.

West Nile also can infect horses, but there is a vaccine for them, so Garrison urges owners to have horses vaccinated. KDHE has received one report of an infected horse in Sedgwick County.