Tennessee is now reporting cases of the mosquito-borne chikungunya virus in two residents who had recently traveled to the Caribbean.

The second confirmed case was from the Knoxville area. The Tennessee Department of Health announced the first confirmed case in Madison County on Friday. The state is also investigating several suspected cases among others who had traveled to Caribbean nations.

Health officials are concerned that chikungunya will establish a foothold in the United States just as West Nile virus has done. Chikungunya is new to the Americas. The U.S. Centers for Disease Control and Prevention warned in December that chikungunya — a virus that originated in Africa — was circulating in the Caribbean for the first time.

Symptoms include fever, headache, fatigue, nausea, vomiting, muscle pain, rash and joint pain.

The only prevention is avoiding mosquito bites.

So far this year, no human cases of West Nile virus have been reported in Tennessee.

But people are getting sick with tick-borne diseases, according to the Tennessee Department of Health. They include 143 cases of Rocky Mountain spotted fever, 20 cases of ehrlichiosis and six cases of Lyme disease.