Ehrlichiosis is caused by several bacterial species in the genus Ehrlichia that affect humans and animals. Currently there are four ehrlichial species that are known to cause disease in humans. Six or fewer confirmed cases per year have been reported in Kentucky since 1991. Human monocytic ehrlichiosis is spread by the bite of an infected tick. Ticks become infected with ehrlichiae while feeding on blood from the host animal in their larval or nymphal state.
Whitetail deer are the major host of the lone star ticks.
The tick develops into the next stage and the ehrlichiae are then transmitted to the following host during the feeding process. Both the nymphal and adult stages are probably capable of transmitting the ehrlichiae to the next host. The incubation period for ehrlichiosis is usually 5-10 days following the tick bite, but can be up to 21 days. The most common symptoms include fever, headache, loss of appetite, muscle aches, and fatigue. Other symptoms sometimes reported are nausea, vomiting, diarrhea, cough, joint pains, confusion and rash.