Authorities in Mississippi said Wednesday they’ve witnessed an increased number of sick or dead deer, and suspect one disease could be the cause, the Associated Press reported.

The Mississippi Department of Wildlife, Fisheries, and Parks believe that the increased number of dead deer is due to Hemorrhagic Disease, also known as blue tongue, the AP reported. The condition is caused by a virus that is transmitted from deer by small bugs like midges and gnats.

“The virus causes internal hemorrhaging and sometimes rapid death occurs,” Dr. Bronson Strickland, a wildlife specialist at the Mississippi State University Extension, said according to the AP. “The virus may cause ulcers which can disrupt digestion.”

Deer with blue tongue experience fevers and find water to cool, according to Strickland. Deer that die due to the virus are often found near local water supplies.

“Far more often, deer become infected but are able to cope with the virus and will have no long-term damage, other than tell-tale indicators they had the virus,” Strickland said.

“This is often seen with deer harvested in the fall and their hooves appear to have sloughed off. The fever a deer experiences while fighting the virus interrupts hoof growth, but the hoof will grow back,” Strickland added.

Blue tongue outbreaks are reported by hunters and the occurrence of sloughing hooves from deer that are killed each season, the AP reported.

“The HD virus is more common in some years and typically follows a three to five-year cycle. Mississippi has had four consecutive years with low HD activity,” William T. McKinley, MDWFP Deer Program Coordinator, said according to WLBT.