Lyme disease is an illness caused by the spirochete bacterium Borrelia burgdorferi. In the Midwest and Eastern U.S., this disease is transmitted to people and animals by the bite of an infected Ixodes scapularis tick. Studies have shown that a tick infected with Borrelia burgdorferi must be attached to its host for at least 48 hours for the bacteria to be transmitted. The disease typically progresses through flu-like symptoms, with an unusual bull’s eye rash to arthritis of the large joints. Some people, when left untreated, may develop complications involving the heart, nervous system, or arthritis.

In Michigan, numerous activities to characterize Lyme disease have been conducted for over ten years. This includes physician-based active surveillance systems, ecological studies, and several laboratory evaluations conducted for the study of Lyme disease. Southern Menominee County is the only area in Michigan considered endemic for Lyme disease. It is the only county in the state where an established population of Ixodes scapularis is known to exist, the only county where Ixodes scapularis ticks have been culture positive for Borrelia burgdorferi, and where rodents infected with B. burgdorferi have been found. Menominee is also the only county in Michigan where the organism has been repeatedly found in clinical specimens from people.

A population of Ixodes scapularis ticks has been recently described in several counties in northern Indiana. A small percentage of these ticks are infected with B. burgdorferi. It is probable that migration of these infected ticks into Michigan’s Lower Peninsula will occur.

Wildlife and Companion Animals

The tick, Ixodes scapularis has a multi-staged life cycle, therefore numerous wildlife species have the opportunity to be exposed to this vector and the Lyme disease bacteria. Small mammals are a preferred host for the tick, but birds, reptiles, and large mammals can also harbor the various stages of the tick. Clinical Lyme disease has not been diagnosed in any wildlife species in Michigan. Deer and white-footed mice can serve as hosts for the tick and the Lyme disease organism.

Clinical Lyme disease in domestic animals may involve many organ systems. Fever, loss of appetite, depression, lethargy, swelling and pain in one or more joints, kidney disease, heart disease, and nervous system disorders have all been reported. An accurate diagnosis can only be made by a veterinarian. A Lyme disease vaccine is available. Consult your veterinarian about the appropriateness of vaccinating your pet and also to discuss recommendations for avoiding ticks.