Lyme disease was discovered in 1975 in the town of Old Lyme, Connecticut. The disease is a bacterial infection caused by the bites of certain infected ticks, and the ticks are much smaller than the ticks that are commonly found on dogs or cattle. The two most important ticks in Lyme disease are the deer tick in the northeast and north central states, and the western black-legged tick in the West. Although the deer ticks that carry the disease are slowly expanding into new areas, there are three general areas in the U.S. that have the highest incidence rate of Lyme disease: the East-coastal states of Massachusetts, the noth central states of Wisconsin, Minnesota, and Michigan, and northern California.
In nature, the Lyme disease bacteria exist in a cycle that involves ticks and small animals. Particularly implicated in Lyme disease are the wild white-footed mouse in the east, and the wood rat in California. Once these rodents become infected, they can spread the disease to the many immature ticks that will likely feed upon them. Adult ticks prefer to feed upon the larger animals, instead of the rodents and small animals preferred by immature ticks. The adult ticks are particularly fond of deer, but as deer are resistent to Lyme infection, their function in the lyme disease cycle is to carry ticks into new areas. Birds may also be responsible for transporting these ticks into new areas.
Lyme disease is not transmitted from person to person. It is only transmitted from ticks to humans, and the infected ticks can also transmit the disease to dogs, cats, and horses. These animals cannot transmit Lyme bacteria to humans, but they can carry ticks on their bodies, increasing their chances of getting infected by the ticks, and increasing the chances of those ticks infecting humans. Ask your veterinarian about appropriate products that will prevent tick infestation for your pet.
The first sign of Lyme disease in humans is usually a characteristic rash, called erythema migrans, which expand outward from the site of the tick bite between 3 and 30 days after the bite. The rash is flat, circular, and is often as large as 2 inches in diameter. As the rash expands, it may begin to take on the appearance of a bull's eye. Infected persons may also experience flu-like symptons, including fever, headache, fatigue, and muscle aches. Persons treated with antibiotics at this stage of infection are likely to make a quick recovery and be competely cured. Persons who do not receive early treatment can develop problems involving the heart, joints and/or nervous system.