Center for Disease Control and Prevention. Questions and Answers About Lyme Disease

Q. How do people get Lyme disease?
A. By the bite of ticks infected with Lyme disease bacteria. (Deer tick)

Q. What is the basic transmission cycle?
A. 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.

Q. Could you get Lyme disease from another person?
A. 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.

Q. What are the signs and symptoms of Lyme disease?
A. 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).

Q. What is the incubation period for Lyme disease?
A. 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.

Q. What is the mortality rate of Lyme disease?
A. Lyme disease is rarely, if ever, fatal.

Q. Can a person be reinfected with Lyme disease?
A. 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.

Q. 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 15,000 cases reported annually, though the disease is greatly under reported. Based on reported cases, during the past ten years 90% of cases of Lyme disease occurred in ten states: More information can be found in the MMWR.

Q. How is Lyme disease treated?
A. 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. (The Medical Letter, Vol. 42(Issue 1077), May 1, 2000)

Q. Is the disease seasonal in its occurrence?
A. 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.

Map of reported cases of Lyme disease in the United States, 1999 Map: Reported cases of Lyme disease in the United States, 1999.

Q. Where is Lyme disease most common?
A. Click on the map at right that shows reported cases of Lyme disease in 1999 by patient's county of residence. Generally, most Lyme disease is endemic in the northeastern and upper Midwest states. (See "Lyme Disease-United States, 1999." MMWR. March 16, 2001;50:181-185.)

Q. Who is at risk for getting Lyme disease? National Lyme disease risk map
A. Persons in endemic areas who frequent sites where infected ticks are common, such as grassy or wooded locations favored by white-tailed deer in the northeastern and upper Midwest states, and along the northern Pacific coast of California.

Q. Is there a vaccine against Lyme disease?
A. As of February 25, 2002 the manufacturer announced that the LYMErix™ Lyme disease vaccine will no longer be commercially available.

Q. Does the Lyme disease vaccine cause arthritis? Are individuals with certain HLA-DR4 genetic subtypes more susceptible to getting arthritis from the vaccine?
A. An association between naturally acquired treatment-resistant Lyme disease arthritis, certain HLA-DR4 genetic subtypes, and high levels of antibody to OspA of naturally acquired Borrelia burgdorferi has been described in the medical literature (1, 2, 3). Because of the relationship between OspA antibodies and treatment-resistant arthritis from naturally acquired infection, CDC's Advisory Committee on Immunization Practices (ACIP) has stated that the vaccine should not be given to persons with treatment-resistant Lyme arthritis (4). However, at this writing there is no scientific evidence that the currently licensed Lyme disease vaccine increases the recipient's risk of arthritis. To the contrary, there is good evidence that the risk of arthritis in vaccine recipients is not significantly different from the risk in individuals who have received placebo without OspA (5). ACIP has not recommended screening of HLA type prior to vaccination. In the absence of evidence that the vaccine causes arthritis, screening for HLA-DR4 subtypes before vaccination would not seem to be a beneficial use of health resources.

1.  Kalish RA, Leong JM, Steere AC. Association of treatment-resistant chronic Lyme arthritis with HLA-DR4 and antibody reactivity to OspA and OspB of Borrelia burgdorferi. Infect Immun 1993;61:2774-2779.

2.  Akin E, McHugh GL, Flavell RA, et al. The immunoglobulin (IgG) antibody response to OspA and OspB correlates with severe and prolonged Lyme arthritis and the IgG response to p35 correlates with mild and brief arthritis. Infect Immun 1999;173-181.

3.  Gross DM, Forsthuber T, Tary-Lehmann M, et al. Identification of LFA-1 as a candidate autoantigen in treatment-resistant Lyme arthritis. Science 1998;281:703-706.

4.  Centers for Disease Control and Prevention. Recommendations for the Use of Lyme Disease Vaccine - Recommendations of the Advisory Committee on Immunization Practices. MMWR 1999;48:1-17.
(Also available in PDF format [742 KB, 39 pages].)

5.  Steere AC, Sikand VK, Meurice F, et al. Vaccination against Lyme disease with recombinant Borrelia burgdorferi outer-surface lipoprotein A with adjuvant. N Engl J Med 1998;339:209-216.

See also: Centers for Disease Control and Prevention-Lyme Disease