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Lyme Disease Frequently Asked Questions (FAQ)

I've been bitten by a tick. Do I have Lyme disease?

If you have not done so already, remove the tick with fine-tipped tweezers.

The chances that you might get Lyme disease from a single tick bite depend on the type of tick, where you acquired it, and how long it was attached to you. Many types of ticks bite people in the U.S., but only blacklegged ticks transmit the bacteria that cause Lyme disease. Furthermore, only blacklegged ticks in the highly endemic areas of the northeastern and north central U.S. are commonly infected. Finally, blacklegged ticks need to be attached for at least 24 hours before they can transmit Lyme disease. This is why it's so important to remove them promptly and to check your body daily for ticks if you live in an endemic area.

If you develop illness within a few weeks of a tick bite, see your health care provider right away. Common symptoms of Lyme disease include a rash, fever, body aches, facial paralysis, and arthritis. Ticks can also transmit other diseases, so it's important to be alert for any illness that follows a tick bite.

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Can Lyme disease be transmitted sexually?

There is no credible scientific evidence that Lyme disease can be spread from person-to-person through sexual contact. The biology of the Lyme spirochete is not consistent with sexual transmission, attempts to demonstrate sexual transmission in infected animals have all failed, and there has not been a single, adequately documented case of sexual transmission of Lyme disease reported in the scientific literature.

The following are some of the false arguments put forth to suggest sexual transmission:

Borrelia burgdorferi and Treponema pallidum (the cause of syphilis) are both spirochetes (cork screw shaped bacteria). Therefore, B. burgdorferi can be transmitted like syphilis. Not true. Although B. burgdorferi and T. pallidum are both spirochetes, they are not closely related. More importantly, they behave very differently within humans in ways that affect their potential for sexual transmission. T. pallidum spirochetes produce moist, superficial skin lesions (e.g., chancres on the genital, anal or oral mucosa) that contain enormous numbers of living spirochetes and are crucial to transmission by sexual contact. In contrast, B. burgdorferi spirochetes cannot survive on the surface of the skin or genital mucosa. They are present only in sparse numbers and only in the deep inner layers of the skin. Whereas syphilis spirochetes can penetrate the skin directly, Lyme disease spirochetes require a highly ordered metabolic process associated with feeding by certain species of ticks.

Borrelia burgdorferi has been isolated from breast milk and semen. Actually, it hasn' t. A single study reportedly found evidence of Borrelia DNA in breast milk using a polymerase chain reaction (PCR) assay. PCR assays detect DNA from dead or living organisms, do not demonstrate the presence of living organisms, and are prone to false positive results. Peer-reviewed and published studies of semen have involved collecting semen from animals, inoculating the semen with bacterial growth media and millions of B. burgdorferi, and then artificially inseminating the animal with the media containing experimentally B. burgdorferi infected semen. The results of these studies provide no evidence that B. burgdorferi occurs naturally in semen.

Husband and wife both have Lyme disease, and at least one doesn' t remember a tick bite. It is not uncommon for more than one person in a household to develop Lyme disease. This occurs because household members share the same environment where infected ticks are abundant. Patients are often unaware of having been bitten because the ticks that transmit Lyme disease are extremely small.

References:

Woodrum JE, Oliver JH, Jr., 1999. Investigation of venereal, transplacental, and contact transmission of the Lyme disease spirochete, Borrelia burgdorferi, in Syrian hamsters. J Parasitol 85: 426-30.

Moody KD, Barthold SW, 1991. Relative infectivity of Borrelia burgdorferi in Lewis rats by various routes of inoculation. Am J Trop Med Hyg 44: 135-9.

Schmid GP, 1989. Epidemiology and clinical similarities of human spirochetal diseases. Rev Infect Dis 11 Suppl 6: S1460-9.

Porcella SF, Schwan TG, 2001. Borrelia burgdorferi and Treponema pallidum: a comparison of functional genomics, environmental adaptations, and pathogenic mechanisms. J Clin Invest 107: 651-6.

Schmidt BL, Aberer E, Stockenhuber C, Klade H, Breier F, Luger A, 1995. Detection of Borrelia burgdorferi DNA by polymerase chain reaction in the urine and breast milk of patients with Lyme borreliosis. Diagn Microbiol Infect Dis 21: 121-8.

Kumi-Diaka J, Harris O, 1995. Viability of Borrelia burgdorferi in stored semen. Br Vet J 151: 221-4.

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Can Lyme disease be transmitted during a blood donation?

Although no cases of Lyme disease have been linked to blood transfusion, scientists have found that the Lyme disease bacteria can live in blood from a person with an active infection that is stored for donation. Individuals being treated for Lyme disease with an antibiotic should not donate blood. Individuals who have completed antibiotic treatment for Lyme disease may be considered as potential blood donors. The Red Cross provides additional information on the most recent criteria for blood donation. 

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Is it true that you can get Lyme disease anywhere in the U.S.?

No. Lyme disease is spread through the bite of a blacklegged tick (Ixodes scapularis or Ixodes pacificus) that is infected with Borrelia burgdorferi. In the United States, most infections occur in the following endemic areas:

  • Northeast and mid-Atlantic, from northeastern Virginia to Maine
  • North central states, mostly in Wisconsin and Minnesota
  • West Coast, particularly northern California

Maps showing the distribution of human cases are based on where people live, which because of travel, is not necessarily where they became infected. Cases are sometimes diagnosed and reported from an area where Lyme disease is not expected, but they are almost always travel-related.

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I live in the southeastern U.S. and get a lot of lone star tick bites. I've heard that I can get “southern Lyme disease”. Is this true?

The lone star tick is primarily found in the southeastern and eastern United States. Lone star ticks do not transmit Lyme disease. However, you are correct to be concerned about this very aggressive species. The lone star tick (Amblyomma americanum) can spread human ehrlichiosis, tularemia, and Southern Tick-Associated Rash Illness (STARI).

The rash of STARI is a red, expanding “bull' s eye” lesion that develops around the site of a lone star tick bite. The rash usually appears within 7 days of tick bite and expands to a diameter of 8 centimeters (3 inches) or more. The rash should not be confused with much smaller areas of redness and discomfort that can occur commonly at tick bite sites. Unlike Lyme disease, STARI has not been linked to arthritis, neurological problems, or chronic symptoms. Nevertheless, the similarity between the STARI bull’s eye rash and the Lyme disease bull’s eye rash has created much public confusion. The pathogen responsible for STARI has not been identified.

In contrast, Lyme disease in North America is caused by a specific type of bacteria, Borrelia burgdorferi, which is transmitted by two species of blacklegged ticks, Ixodes scapularis and Ixodes pacificus. While blacklegged ticks exist in the southern U.S., their feeding habits in this region make them much less likely to maintain, sustain, and transmit Lyme disease.

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I have heard that the diagnostic tests that CDC recommends are not very accurate. Can I be treated based on my symptoms or do I need to use a different test?

You may have heard that the blood test for Lyme disease is correctly positive only 65% of the time or less. This is misleading information. As with serologic tests for other infectious diseases, the accuracy of the test depends upon the stage of disease. During the first few weeks of infection, such as when a patient has an erythema migrans rash, the test is expected to be negative.

Several weeks after infection, currently available ELISA, EIA and IFA tests and two-tier testing have very good sensitivity.

It is possible for someone who was infected with Lyme disease to test negative because:

  1. Some people who receive antibiotics (e.g., doxycycline) early in disease (within the first few weeks after tick bite) may not develop antibodies or may only develop them at levels too low to be detected by the test.
  2. Antibodies against Lyme disease bacteria usually take a few weeks to develop, so tests performed before this time may be negative even if the person is infected. In this case, if the person is retested a few weeks later, they should have a positive test if they have Lyme disease. It is not until 4-6 weeks have passed that the test is likely to be positive. This does not mean that the test is bad, only that it needs to be used correctly.

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I am pregnant and just found out I have Lyme disease. What should I do?

If you are pregnant and suspect you have contracted Lyme disease, contact your physician immediately. Untreated Lyme disease during pregnancy may lead to infection of the placenta and possible stillbirth.

Thankfully, no serious effects on the fetus have been found in cases where the mother receives appropriate antibiotic treatment for her Lyme disease. In general, treatment for pregnant women with Lyme disease is similar to that of non-pregnant adults, although certain antibiotics, such as doxycycline, are not used because they can affect fetal development.

Additionally, there are no reports of Lyme disease transmission from breast milk.

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If I have been diagnosed with Lyme disease, do I need to get tested for other tickborne diseases (coinfections)?

Maybe. The blacklegged ticks that transmit Lyme disease can sometimes also transmit babesiosis and anaplasmosis. Fortunately, Lyme disease and anaplasmosis are treated with the same antibiotics, so if you are receiving treatment for Lyme disease, anaplasmosis will be treated at the same time (Wormser et al. 2006). Babesiosis is a parasitic disease that is treated with different medications. If your Lyme disease symptoms do not seem to be going away after taking antibiotics, see your health care provider.

There is, however, a great deal of misinformation regarding tickborne coinfections on the internet. The possibility of having three or more tickborne infections or having pathogens such bartonella or mycoplasma (which have not been shown to be tickborne), is extremely unlikely.

The chance of having multiple tickborne infections depends on your location. Several studies have looked at the prevalence of these different organisms in ticks, though methods and locations are very different. Studies have shown that the rate of coinfection in blacklegged ticks varies by region from 1 to 28%. The most common coinfection in ticks is Borrelia burgdorferi (Lyme disease) and Anaplasma phagocytophilum (anaplasmosis). The frequency of tickborne coinfections in Lyme disease patients from endemic areas ranges from 4 to 45% (Swanson et al. 2006). From 2 to 12% of patients with early Lyme disease may also have anaplasma infection, and 2 to 40% of patients with early Lyme disease may also have babesia infection, depending on the region (Wormser, 2006).

References:

Swanson, et al. Coinfections acquired from Ixodes ticks. Clin Microbiol Rev. 2006 Oct;19(4):708-27.

Wormser, Gary. “Clinical practice. Early Lyme disease.” N Engl J Med. 2006 Jun 29;354(26):2794-801.

Wormser et al. “The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: Clinical practice guidelines by the Infectious Diseases Society of America” Clinical Infectious Diseases 2006;43:1089-1134.

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I have been sick for a few years with joint and muscle pain, fatigue, and difficulty thinking. I was tested for Lyme disease using a Western Blot test. The “IgM” Western Blot test was positive but the “IgG” Western Blot test was negative. Is Lyme disease the cause of my symptoms?

Probably not. First, you should only have an immunoblot (such as an FDA-approved Western Blot or striped blot) test done if your blood has already been tested and found reactive with an EIA or IFA.

Second, the IgM Western Blot test result is only meaningful during the first 4 weeks of illness. If you have been infected for longer than 4-6 weeks and the IgG Western Blot is still negative, it is highly likely that the IgM result is incorrect (e.g., a false positive). This does not mean that you are not ill, but it does suggest that the cause of illness is something other than the Lyme disease bacterium. For more information, see the in-depth discussion regarding testing for Lyme disease.

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Where can I get a test to make sure that I am cured?

As with many infectious diseases, there is no test that can “prove” cure. Tests for Lyme disease detect antibodies produced by the human immune system to fight off the bacteria (Borrelia burgdorferi) that cause Lyme disease. These antibodies can persist long after the infection is gone. This means that if your blood tests positive, then it will likely continue to test positive for months or even years even though the bacteria are no longer present.

A research tool called PCR can detect bacterial DNA in some patients. Unfortunately, this is also not helpful as a test of whether the antibiotics have killed all the bacteria. Studies have shown that DNA fragments from dead bacteria can be detected for many months after treatment. Studies have also shown that the remaining DNA fragments are not infectious. Positive PCR test results are analogous to a crime scene – – just because a robbery occurred and the robber left his DNA, it doesn' t mean that the robber is still in the house. Similarly, just because DNA fragments from an infection remain, it doesn' t mean the bacteria are alive or viable.

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My serologic (blood) test for Lyme disease is still positive even though I finished 3 weeks of antibiotics. Does this mean I am still infected?

No. The tests for Lyme disease detect antibodies made by the immune system to fight off the bacteria, Borrelia burgdorferi. Your immune system continues to make the antibodies for months or years after the infection is gone. This means that once your blood tests positive, it will continue to test positive for months to years even though the bacteria are no longer present. Unfortunately, in the case of bacterial infections, these antibodies don' t prevent someone from getting Lyme disease again if they are bitten by another infected tick.

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I heard that if I get Lyme disease I will always have it. Is that true?

No. Patients treated with antibiotics in the early stages of the infection usually recover rapidly and completely. Most patients who are treated in later stages of the disease also respond well to antibiotics, although some may have suffered long-term damage to the nervous system or joints. Approximately 10-20% of patients experience fatigue, muscle aches, sleep disturbance, or difficulty thinking even after completing a recommended course of antibiotic treatment. These symptoms cannot be cured by longer courses of antibiotics, but they generally improve on their own, over time.

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Can you recommend a doctor who is familiar with diagnosing and treating Lyme disease?

The American Lyme Disease Foundation (ALDF) keeps a national list of doctors who are familiar with the diagnosis and treatment of Lyme disease and other tickborne infections. You can access this list by:

Please note that CDC cannot evaluate the professional qualifications and competence of individual doctors. The inclusion of a doctor on the ALDF list should not be seen as an endorsement by CDC. You could also choose to see a doctor in your area who specializes in infectious diseases. Often these doctors are affiliated with a university.

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How many people get Lyme disease?

Each year, approximately 30,000 cases of Lyme disease are reported to CDC by state health departments and the District of Columbia. However, this number does not reflect every case of Lyme disease that occurs in the United States every year.

Surveillance systems provide vital information but they do not capture every illness. Because only a fraction of illnesses are reported, researchers need to estimate the total burden of illness to set public health goals, allocate resources, and measure the economic impact of disease. CDC uses the best data available and makes reasonable adjustments—based on related data, previous study results, and common assumptions—to account for shortcomings and missing pieces of information.

To improve public health, CDC wants to know how many people are actually diagnosed with Lyme disease each year and for this reason is conducting three complementary studies:

  • Project 1 estimates the number of people diagnosed with Lyme disease based on medical claims information from a large insurance database.
  • Project 2 estimates the number of people who test positive for Lyme disease based on data obtained from a survey of clinical laboratories.
  • Project 3 uses survey data to estimate the number of people who report that they’ve been diagnosed with Lyme disease in the previous year.

Preliminary results from three different evaluation methods suggest that the number of people diagnosed with Lyme disease each year in the United States is around 300,000. Notably, this new estimate does not affect our understanding of the geographic distribution of Lyme disease. Most Lyme disease cases reported to CDC through national surveillance are concentrated heavily in the Northeast and upper Midwest, with 96 percent of reported cases occurring in 13 states. The preliminary results obtained using the new estimation methods mirror the geographic distribution of cases that is shown by national surveillance.

In August 2013, CDC scientists presented early results of these studies along with other scientists at the International Conference on Lyme Borreliosis in Boston, Mass. At the meeting, they described their different approaches (called research methods) and preliminary findings to other scientists. They will receive feedback and gain the insight of other scientists who are working on Lyme disease. This type of interaction is an important part of the scientific peer-review process. It makes science transparent and strengthens the quality of methods and findings that come from the methods. Finalized estimates will be published when these studies are complete.

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How are cases reported to CDC?

As with most other reportable diseases, reporting requirements for Lyme disease are determined by state laws or regulations. In most states, Lyme disease cases are reported by licensed health care providers, diagnostic laboratories, or hospitals. States and the District of Columbia remove all personally identifiable information, then share their data with CDC, which compiles and publishes the information for the Nation. CDC has no way of linking this information back to the original patient.

CDC summarizes national surveillance data based on these reports, and publishes results in the CDC publication, the Morbidity Mortality Weekly Report. The latest summary was published in the MMWR Surveillance Summary for Lyme Disease--United States, 1992-2006.

The goal of Lyme disease surveillance is not to capture every case, but to systematically gather and analyze public health data in a way that enables public health officials to look for trends and take actions to reduce disease and improve public health.

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Are more recent numbers available?

Cases of Lyme disease and other reportable conditions are published each week in the MMWR. However, these weekly numbers are provisional and often change when all the data become available after the end of the year. CDC publishes finalized data only after all states and territories have certified their reports. Finalized data for a given year are generally not available until the fall of the following year.

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What is a surveillance case definition?

Reporting of all nationally notifiable diseases, including Lyme disease, is based on standard surveillance case definitions developed by the Council of State and Territorial Epidemiologists (CSTE) and CDC. The usefulness of public health surveillance data depends on its uniformity, simplicity, and timeliness. Surveillance case definitions establish uniform criteria for disease reporting and should not be used as the sole criteria for establishing clinical diagnoses, determining the standard of care necessary for a particular patient, setting guidelines for quality assurance, or providing standards for reimbursement. The national surveillance case definition for Lyme disease is available on CDC' s web site.

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What' s the definition of a "Lyme disease endemic county"?

States determine which counties are endemic for Lyme disease--not CDC. Furthermore, not all states use the same criteria for determining endemic counties. The Council of State and Territorrial Epidemiologists (CSTE) considers a county to be endemic for Lyme disease if:

  • There are at least two confirmed human cases that were acquired in (not just reported from) that county, or
  • There are established populations of Ixodes scapularis or Ixodes pacificus are infected with B. burgdorferi

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Why does CDC only link to one set of treatment guidelines?

CDC believes that the Infectious Disease Society of America (IDSA) guidelines currently represent the best available synthesis of the medical literature on the diagnosis and treatment of Lyme disease. The IDSA, with input from CDC expert and other doctors, has developed and published Lyme disease treatment guidelines. Please note that the CDC does not produce Lyme disease treatment guidelines.

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What is CDC doing about Lyme disease?

CDC has a program of service, research, and education focusing on the prevention and control of Lyme disease. Activities of this program include:

  • Maintaining and analyzing national surveillance data for Lyme disease
  • Conducting epidemiologic investigations
  • Offering diagnostic and reference laboratory services
  • Developing and testing strategies for the control and prevention of this disease in humans
  • Supporting education of the public and health care providers

In addition, the TickNET program supports research that contributes to the understanding of tickborne diseases.

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