LYME DISEASE

BACK TO TICK ARTICLE   TICK ELIMINATION    TICK REMOVAL 

Lyme disease is caused by a spirochete (or type of bacteria), called Borrelia burgdorferi, which affects humans. This disease organism is vectored principally by a hard tick, Ixodes dammini, which commonly attacks white-tailed deer. Lyme disease was first recognized and reported as a cluster of cases which occurred around Lyme, Connecticut in 1975. Since then, three areas in the United States are now identified where this disease organism is known to be endemic, or occurring naturally. These are areas of the Northeast (in coastal areas from northern Virginia to southern Maine,) the northern Midwest (Minnesota and Wisconsin) and the West (parts of California, Oregon, Utah and Nevada.) Most occur in the northeastern United States, but cases of Lyme Disease have been reported in at least 25 states.

Symptoms of Lyme disease can be severe, including acute headache to more serious nervous system impairment, symptoms resembling rheumatoid arthritis, expanding red rash on or near the tick bite, low grade fever, abdominal and joint pain, dizziness and stiff neck. Most of the cases occur during the summer, because this is the time people will be out hiking in areas infested by the tick vector, and might receive a bite from an infected tick. Persons living in or visiting the Lyme disease areas who develop these symptoms after receiving a tick bite should consult their physician, and explain that they received a tick bite and suspect Lyme disease. Effective treatments for the disease are available to physicians.

Ixodes dammini has a rather complex two-year life cycle. Eggs are deposited in the spring and the tiny larvae emerge several seeks later. These immature ticks feed once during the summer, usually for two days on the blood of small mammals such as field mice. Larvae molt the following spring into nymphs, which also feed once (for 3-4 days) during the summer, either on field mice or larger mammals such as dogs, deer or humans. It is the nymphal stage of Ixodes dammini which is most likely to attack and bite humans. These nymphs will then molt into adults in the fall. Adult ticks attach themselves to a host, usually the white-tailed deer, where they then mate. The adult male ticks then fall off the host and die, and the females obtain the blood meal necessary for successful egg production. In areas where Lyme disease is highly endemic, such as the northeastern United States, upwards of 80-90% of the Ixodes dammini ticks collected in the field have the causal organism (B. burgdorferi) in their bodies.

The principles of tick management will be much the same for Ixodes dammini as for other ticks, except that I. dammini occurs primarily in field and wooded areas rather than yards or urban and suburban parks.