Lyme disease is an infection that's spread by Ixodes ticks which are black-legged or deer ticks. These ticks can carry the bacteria Borrelia Burgdorferi. These ticks acquire the bacteria from mice and then infect humans by biting them and passing the bacteria into a person's bloodstream. These ticks are smaller than dog ticks and harder to detect. Immature ticks, or nymphs, are about the size of a poppy seed; adult ticks are the size of a sesame seed.

The majority of reported Lyme disease cases occur in the northeastern and upper midwestern areas of the United States because these two zones and the Pacific Northwest are the natural habitat of the Ixodes tick and its carriers. Some cases of Lyme disease have also been reported in the southeastern and southern midwestern states, although the Centers for Disease Control and Prevention (CDC) considers these low-risk areas.

According to the CDC, the states that report the most cases of Lyme disease are: Connecticut, Delaware, Maryland, Massachusetts, Minnesota, New York, New Jersey, Pennsylvania, Rhode Island, Wisconsin.

Lyme disease is the leading tick-borne disease in the United States, with more than 16,000 cases reported to the CDC in 1999, but it is not the only disease carried by deer ticks. Two other diseases, human granulocytic ehrlichiosis (HGE) and babesiosis, are also transmitted through deer tick bites.

There has been a rise in the number of reported cases of HGE, with many occurring in the upper midwestern region and coastal northeastern region of the United States. HGE, which produces severe flu-like symptoms such as headache, fever, nausea, and overall achiness, can be successfully treated with antibiotics.

Symptoms of babesiosis include weakness, fatigue, fever, drenching sweats, muscle soreness, and headaches. Treatment includes quinine (a drug used for malaria) and antibiotics.

Lyme disease is not transmitted from person to person. The risk of developing Lyme disease depends on an individual's exposure to ticks. The Ixodes tick is present only in the northeastern, upper midwestern, and Pacific Northwest regions of the United States. Children and adults who spend a lot of time outdoors are more likely to contract Lyme disease. Exposure to wooded areas increases risk.

Very rarely, Lyme disease contracted during pregnancy may infect the fetus. Ask your obstetrician for more information.

Domestic animals, such as dogs and cats, may become infected with Lyme disease bacteria and may carry infected ticks into areas where humans live.