Medical experts have discovered six new cases of the newly-discovered Heartland virus. 

Two northwestern Missouri farmers first reported the virus back in 2009, but physicians believed it was a tick-borne illness called ehrlichiosis, a Centers for Disease Control and Prevention (CDC) news release reported. 

The patients did not improve with standard ehrlichiosis treatment; eventually the CDC and other state and local partner identified the illness as a previously-unknown virus in the phlebovirus family.

Five new cases have now been reported in Missouri and one in Tennessee. All of the eight (two in 2009) reported cases have occurred in white men over the age of 50. 

Symptoms of the virus include: "fever, fatigue, loss of appetite, headache, nausea, or muscle pain," the news release reported. Four of the recent cases resulted in hospitalization. One patient passed away, but it is unclear if the cause of death was related to the virus or other health problems. 

Five out of the six new Heartland virus patients reported tick bites in the weeks leading up to their illness. 

"During the past two years, CDC has worked closely with state health departments, hospitals, and many experts from universities and other federal agencies to learn more about Heartland virus," Roger Nasci, Ph.D., chief of CDC's Arboviral Diseases Branch, said in the news release. "By gathering information about the disease Heartland virus causes, and about how it's spread to people, we hope to better understand the potential impact on the public's health and how we can help protect people from this virus."

The CDC has already developed blood tests to confirm new cases of the virus. There is currently no treatment for the virus, but IV fluids and fever reducers are believed to help improve the patients' conditions. 

In order to reduce the risk of contracting the Heartland virus the CDC recommends those living in affected areas should: "Avoid wooded and bushy areas with high grass and leaf litter; Use insect repellent when outdoors; Use products that contain permethrin on clothing; Bathe or shower as soon as possible after coming indoors to wash off and more easily find ticks that are crawling on you; Conduct a full-body tick check after spending time outdoors; and Examine gear and pets, as ticks can "ride" into the home and attach to a person later," the news release reported.