The bacteria is transmitted to humans through the bite of infected ticks, which acquire the agents after feeding on infected animal reservoirs. Ixodes scapularis and Amblyomma americanum ticks are capable of transmitting this disease in Michigan.

Symptoms:		Ehrlichiae dividing in white blood cell
	Fever
	Headache
	Malaise and muscle aches.
	Other signs may include nausea, vomiting, diarrhea, cough, joint pain, confusion, and occasionally, a rash.

HGE has not yet been found in Michigan but it has been diagnosed in patients in Wisconsin and Minnesota. Also, HME is occasionally reported in Indiana. Because the vector Ixodes scapularis is found in Michigan and the state’s close proximity to the state of Wisconsin, the emergence of this disease is being closely monitored in Michigan.

Wildlife and Companion Animals

The preferred reservoir hosts for HME are white-tailed deer and small rodents, and for HGE, white-tailed deer, elk, meadow voles, white-footed mice, coyotes, and wood rats. None of these wildlife species have been diagnosed with the disease but they can act as hosts for the Ehrlichia organism.

The disease in dogs, caused by Ehrlichia canis, and other Ehrlichia species, mimics RMSF. Ehrlichia risticii causes a similar disease known as Potomac Horse Fever (PHF) in horses. Diarrhea and laminitis are also frequently reported with PHF. These diseases cannot spread directly from dog to dog or horse to horse but must pass through the arthropod (tick) vector. No PHF vector has yet been definitely identified.