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.
 

How do people get Lyme disease?
By the bite of a tick infected with Lyme disease bacteria.

What is the basic transmission cycle?
Immature ticks become infected by feeding on small rodents, such as the white-footed mouse, and other mammals that are infected with the bacterium Borrelia burgdorferi. In later stages, these ticks then transmit the Lyme disease bacterium to humans and other mammals during the feeding process. Lyme disease bacteria are maintained in the blood systems and tissues of small rodents.

Could you get Lyme disease from another person?
No, Lyme disease bacteria are NOT transmitted from person-to-person. For example, you cannot get infected from touching or kissing a person who has Lyme disease, or from a health care worker who has treated someone with the disease, or by sexual contact.

What are the signs and symptoms of Lyme disease?
Within days to weeks following a tick bite, 80% of patients will have a red, slowly expanding "bull's-eye" rash (called erythema migrans), accompanied by general tiredness, fever, headache, stiff neck, muscle aches, and joint pain. If untreated, weeks to months later some patients may develop arthritis, including intermittent episodes of swelling and pain in the large joints; neurologic abnormalities, such as aseptic meningitis, facial palsy, motor and sensory nerve inflammation (radiculoneuritis) and inflammation of the brain (encephalitis); and, rarely, cardiac problems, such as atrioventricular block, acute inflammation of the tissues surrounding the heart (myopericarditis) or enlarged heart (cardiomegaly).

What is the incubation period for Lyme disease?
For the red "bull's-eye" rash (erythema migrans), usually 7 to 14 days following tick exposure. Some patients present with later manifestations without having had early signs of disease.

Can a person be reinfected with Lyme disease?
Yes. Having had Lyme disease doesn't protect against reinfection. Some persons have had Lyme disease more than once after re-exposure to infective tick bites. This stresses the need for continued tick bite prevention activities such as wearing appropriate clothing when in tick-infested areas, daily tick checks, and quick removal of attached ticks.

How many cases of Lyme disease occur in the U.S.?
A. Lyme disease is the leading cause of vector-borne infectious illness in the U.S. with about 23,000 cases reported in 2002, though the disease is greatly under reported. Twelve states account for over 90% of reported cases.

How is Lyme disease treated?
According to treatment experts, antibiotic treatment for 3-4 weeks with doxycycline or amoxicillin is generally effective in early disease. Cefuroxime axetil or erythromycin can be used for persons allergic to penicillin or who cannot take tetracyclines. Later disease, particularly with objective neurologic manifestations, may require treatment with intravenous ceftriaxone or penicillin for 4 weeks or more, depending on disease severity. In later disease, treatment failures may occur and retreatment may be necessary.

Is the disease seasonal in its occurrence?
Yes, Lyme disease is most common during the late spring and summer months in the U.S. (May through August) when nymphal ticks are most active and human populations are frequently outdoors and most exposed.

Where is Lyme disease most common?
Click on the map at right that shows reported cases of Lyme disease in 2000 by patient's county of residence. Generally, Lyme disease is endemic in the northeastern and upper midwest states.

Ticks that Most Commonly Transmit B. burgdorferi in the U.S.

Ixodes scapularis -most common in the northeast and midwest. Also found in the south and southeast.