Lyme disease was named in 1977
when arthritis was observed in a cluster of children in and
around Lyme, Connecticut. Other clinical symptoms and environmental
conditions suggested that this was an infectious disease probably
transmitted by an arthropod. Further investigation revealed
that Lyme disease is caused by the bacterium, Borrelia burgdorferi.
These bacteria are transmitted to humans by the bite of infected
deer ticks and cause more than 16,000 infections in the United
States each year.
Vector: Black-legged ticks (Ixodes
scapularis) are responsible for transmitting Lyme disease bacteria
to humans in the northeastern and north-central United States.
On the Pacific Coast, the bacteria are transmitted to humans
by the western black-legged tick (Ixodes pacificus). Ixodes
ticks are much smaller than common dog and cattle ticks. In
their larval and nymphal stages, they are no bigger than a pinhead.
Ticks feed by inserting their mouths into the skin of a host
and slowly take in blood. Ixodes ticks are most likely to transmit
infection after feeding for two or more days.
Risk: In the United States, Lyme
disease is mostly localized to states in the northeastern, mid-Atlantic,
and upper north-central regions, and to several counties in
northwestern California. In 1999, 16,273 cases of Lyme disease
were reported to the Centers for Disease Control and Prevention
(CDC). Ninety-two percent of these were from the states of Connecticut,
Rhode Island, New York, Pennsylvania, Delaware, New Jersey,
Maryland, Massachusetts, and Wisconsin.
Individuals who live or work in residential areas surrounded
by tick-infested woods or overgrown brush are at risk of getting
Lyme disease. Persons who work or play in their yard, participate
in recreational activities away from home such as hiking, camping,
fishing and hunting, or engage in outdoor occupations, such
as landscaping, brush clearing, forestry, and wildlife and parks
management in endemic areas may also be at risk of getting Lyme
Prevention and Treatment: It is
important to remember that prevention measures can be effective
in reducing your exposure to infected ticks, and most patients
can be successfully treated with antibiotic therapy when diagnosed
in the early stages of Lyme disease.