Oklahoma and Arkansas have also seen cases of the virus, according to the Indiana State Department of Health.
The first United States case involved a 68-year-old man in Kansas, John Seested, who died two weeks after being bitten by a tick.
The Department of Health says "Although Meramec State Park is an area of interest in the Bourbon virus investigation, health officials have advised that at this time there is no information to suggest the potential exposure risk at the park is any greater than anywhere else in Missouri".
Symptoms can include swelling of the brain, fever, headache, vomiting, weakness, confusion, loss of coordination, speech difficulties, and seizures.
Tamela Wilson, 58, is the first person in Missouri to test positive for the tick-borne illness known as the Bourbon Virus. However, DHSS statistics indicate that people over age 50 and those with chronic health problems are more likely to develop a serious illness that can lead to complications.
Wilson removed two ticks from her body a couple of weeks before she was admitted to Barnes-Jewish Hospital on May 31 with a low white blood cell count. Lyme disease, ehrlichiosis and Rocky Mountain spotted fever are all examples of tick-borne diseases found in Indiana.More news: Milan, è fatta per Biglia. L'argentino sarà rossonero
There's no known treatment for Bourbon virus, but Hawkinson said research is ongoing and in the meantime there are measures hospitals can take to improve patients' chances of fighting off the disease. The mother of three lived and worked at Meramec State Park in Sullivan for the last 10 years.
The two viruses are extremely rare and do not constitute a public health threat, Lawrence said. There have been 24 total cases statewide since 2000. If caught early, it can be treated easily with antibiotics.
Geoff Wilson, the tick-borne illness victim's father, said the doctors at the Missouri hospital were "beside themselves" and described the case as a "medical mystery".
Lawrence compares the situation to the Ebola scare of 2014.
"You have to be knowledgeable about that, you have to be aware of that, and that's why it's always important, after you come in from the outdoors, that you do a tick check", said Skalicky. "We have a virus that doesn't have a cure, and that's scary", May said.
After outdoor activities, people should conduct full-body tick checks using a hand-held or full-length mirror.