Frequently Asked Questions
We are developing this page to offer specific information on Lyme disease and other tick-borne infections that goes beyond the scope of that provided elsewhere on our web site. Please check regularly for new updates.
Categories (in alphabetical order):
Prevention
Risk assessment (personal)
Testing (medical)
Tick ecology
Tick removal
Treatment
How many Lyme disease patients get erythema migrans?
Is long-term antibiotic therapy safe?
Is there a vaccine for Lyme disease?
Prevention
How can I protect myself and my family against Lyme disease?
For a detailed discussion on Lyme disease prevention, please see the Prevention and Control section of our Lyme disease page.
Risk Assessment (Personal)
How do I know I'm at risk for contracting Lyme disease?
Think of your potential risk as two-fold: 1) the risk of exposure to ticks and 2) the risk of contracting Lyme disease following a tick bite.
1) To assess your risk of exposure to deer ticks, ask yourself the following questions:
a) Do I live or vacation in a Lyme disease-endemic area (an area of high incidence or high risk)?
b) Do I engage in high-risk activities, like hiking, gardening, or otherwise making contact with overgrown vegetation?
c) Does my occupation require frequent outdoor work?
d) Do I tend not to take precautions (e.g., wear tick repellant, check myself for ticks) against tick bites when I spend time outdoors?
If you answered yes to only one of these questions, your risk of tick exposure is low. If you answered yes to both a) and any one of the other questions, your risk of exposure is high and you should take steps to prevent tick bites. If you answered yes to a) and two or more of the other questions, your risk is extremely high and you stand a good chance of being bitten by a tick unless you reduce your risk by avoiding tick habitat or conscientiously take precautions (for specific precautions, see Prevention and Control on our Lyme disease page).
2) To assess your risk of contracting Lyme disease following a known tick bite, ask yourself the following questions:
a) Do I live in a Lyme disease-endemic area (an area of high incidence or high risk)?
b) Is the tick I just removed either a deer tick or a western black-legged tick?
c) If so, did the tick appear engorged (swollen like a balloon) vs. flattened?
If you answered no to any one or two of these questions, your risk of contracting Lyme disease is low, but you should nevertheless be watchful for possible symptoms. If you answered yes to all three questions, your risk for Lyme disease is high, and you should be particularly alert for any early symptoms, including the rash, that might develop in the next several weeks. If symptoms appear, call your physician immediately.
How can I determine if my occupation places me at risk for Lyme disease?
Any occupation that requires outdoor work in an endemic area should be considered a risk for Lyme disease. Such occupations include utility work, surveying, landscaping, forestry, gardening, and right-of-way roadside clearing.
How do I determine if I live in an endemic area?
In the United States, the Centers for Disease Control and Prevention has determined that endemic areas include non-urban communities throughout much of the Northeast (Southern Maine to Virginia), parts of the upper Midwest (Minnesota and Wisconsin) and areas along the West Coast (northern California and Oregon). State and county health departments can offer guidelines concerning the risk of Lyme disease for a specific area.
Testing (Medical) (Updated 8-01-03)
I've heard Lyme disease testing is unreliable. What are the available tests, and how reliable are they?
One of the most vexing issues in Lyme disease diagnosis is the debate over the role and reliability of currently available laboratory tests. Patients and their treating physicians may often turn to excessive or inappropriate testing after receiving negative results using the standard two-step testing method (ELISA and Western blot). This practice can result in conflicting evidence leading to misdiagnosis and unnecessary treatment while the real cause of illness remains obscure.
The Lyme disease tests described below are currently available for commercial or experimental use, but differ in their utility and diagnostic value.
FDA Approved Tests:
The enzyme-linked immunoassay (ELISA) is widely accepted and routinely performed as the first step in confirming a clinical (symptom-based) Lyme disease diagnosis, especially in patients whose symptoms did not include the expanding rash typical of early disease. The ELISA screens for elevated blood levels of antibodies produced in response to Borrelia burgdorferi, the bacteria that cause Lyme disease. If performed at least four weeks after a tick bite, this test will identify virtually all patients with Lyme disease, but 5% to 7% of those unexposed to the disease will also test positive. The ELISA is therefore meant to provide only preliminary screening, and all positive results must be confirmed by a second test, the Western blot.
The more accurate Western blot specifies which Lyme-associated antibodies are present in the bloodstream, and is routinely used to confirm, or in some cases contradict, positive ELISA results. A positive ELISA followed by a negative Western blot indicates that Lyme disease is not an appropriate diagnosis. Although the Western blot is not foolproof and should not be used to diagnose Lyme disease without accompanying symptomologic evidence, the ELISA/Western blot combination is considered the most reliable testing method currently available.
The polymerase chain reaction (PCR) test is a very sensitive assay that detects the DNA of B. burgdorferi. However, certain limitations prevent the PCR from being widely used. First, B. burgdorferi bacteria do not persist in easily obtainable fluids such as blood, synovial (joint) fluid or spinal fluid, but typically bind to joint and nerve tissues. A PCR done on spinal fluid may be positive in early neurologic disease (e.g., Lyme meningitis) but is usually negative in a patient with long-term central nervous system damage. Second, a PCR can be easily contaminated, producing false positive results. For this reason, a positive PCR in a patient whose standard blood tests (ELISA and Western blot) are negative must be viewed with skepticism.
Experimental:
The newly introduced C6 Lyme Peptide ELISA (C6LPE) is a simple, sensitive and specific antibody titer that is likely to significantly improve the reliability of Lyme disease testing.
The Lyme urine antigen test (LUAT) is an antigen capture assay reported by its manufacturer to detect certain proteins exhibited by B. burgdorferi. However, although heavily marketed on the Internet, it has no proven value in the diagnosis or management of Lyme disease and has not been FDA-approved for commercial use. The LUAT has not yet been independently validated, can lead to misdiagnosis and unnecessary treatment, and is not recommended by the Centers for Disease Control and Prevention.
A B. burgdorferi blood culture technique described in the November-December 1998 issue of the Journal Infection was reported to have been developed in an effort to establish a new standard in laboratory diagnosis of Lyme disease. However, follow up studies have revealed that the media used in the study fails to grow any B. burgdorferi, whether using the organism from a lab or blood from serologically confirmed Lyme disease patients (Tilton 2001). Although B. burgdorferi can occasionally be cultured from the blood in standard (BSK-H) media, claims of routine culturing from Lyme disease patients in non-standard media cannot be verified.
Tick Ecology (Updated 2006)
What is a tick?
Ticks belong to the arachnid family, which means they are related to spiders and scorpions. They are therefore not true insects.
Ticks are parasites that feed by latching on to an animal host, embedding their mouthparts into the host's skin and feeding on its blood. This method of feeding makes ticks the perfect vectors (organisms that harbor and transmit disease) for a variety of pathogenic agents. Ticks are responsible for at least 10 different diseases in humans in the United States, including Lyme disease, Rocky Mountain spotted fever, ehrlichiosis and babesiosis, and several other newly identified diseases.
What species of ticks can transmit Lyme disease to humans?
The deer tick (Ixodes scapularis) in the eastern United States and its close relative the Western black-legged tick (Ixodes pacificus) on the Pacific Coast are the only tick species currently known to transmit the Lyme disease spirochete (a type of bacterium) to humans. Other tick species have been observed to harbor the spirochete but apparently cannot transmit it to their human hosts.
What does a deer tick look like?
The first thing to remember about deer ticks is that they come in three different sizes and color patterns, depending on which stage of their lifecycle you're looking at. Just as humans have successive life stages (e.g., child, adolescent, adult), a deer tick hatches from its egg as a light tan, translucent larva (about the size of a period in newsprint), molts into a blackish nymph (about the size of a poppy seed), and eventually molts a second time into a brick-red adult female (about the size of a sesame seed) or a black adult male (slightly smaller than the female). Improved photo images of the deer tick's three life stages and other species of ticks for comparison will soon be posted on this web site.
How many hosts does a deer tick feed on (and potentially infect) during its lifespan?
The number of hosts the deer tick feeds on is governed by its lifecycle. Please see our section on deer tick ecology for a complete description of the two-year deer tick lifecycle.
What time of year are ticks active?
At lower latitudes and at higher latitudes when winters are mild, ticks can be active all year round. In southern New England during the '97/'98 winter season, adult deer ticks were observed to be active both in December and January. Generally, deer ticks can be active any time the temperature is above about 45° F.
Both deer tick nymphs and adults (but not larvae) can be infected with the Lyme disease spirochete, but their respective numbers peak during different seasons. The smaller (and harder-to-see) nymphs emerge from dormancy in early May, peak throughout June and taper off in August and September. (Careful self-inspection is required to detect nymphs, which are only the size of a poppy seed.) Adult ticks emerge in September and peak in late October into November.
Adults unsuccessful in finding hosts become inactive during the winter months (unless the winter is mild), re-activating again in February and March in a final effort to find a host, feed, mate and reproduce before dying. (For a visual representation of the deer tick's two-year life-cycle, see the life-cycle diagram on our Deer Tick Ecology page.)
What habitats do the ticks that transmit Lyme disease prefer?
Deer ticks generally wait for a passing host under leaf litter or on plant stems, leaf tips and blades of grass within three feet of the ground. They can be found in any kind of vegetation, including well-kept lawns and gardens. However, they are most likely to be in moist, wooded areas, in overgrown fields or dense underbrush, around rock walls, and especially along the edge of lawns and open areas.
Tick Removal
What is the best way to remove a tick?
(Please see How to Remove a Tick on our Lyme Disease page.)
Treatment (Posted 7-18-00)
It seems many doctors have different opinions about Lyme disease treatment. Is there any consensus on how best to treat this disease?
Lyme disease is a bacterial infection, like strep throat or a urinary tract infection, and is usually successfully treated with antibiotics - medications designed to kill bacteria. Different bacteria have different susceptibilities to particular antibiotics. Oral amoxicillin, doxycycline and cefuroxime axetil have been shown to effectively kill Borrelia burgdorferi, the bacteria that causes Lyme disease, and are recommended in treatment guidelines as first-line therapy in most early and late-stage cases. Several other oral antibiotics (azithromycin, erythromycin and clarithromycin) are slightly less effective against Lyme disease, and should be used only as alternative treatments for patients who have allergies or adverse responses to first-line therapies. More aggressive intravenous antibiotic therapy using cefotaxime or ceftriaxone are recommended in cases with severe heart or neurological involvement.
Major medical textbook guidelines recommend that both oral and IV treatment last two, three or four weeks, depending on the stage of disease, symptoms presented, and their severity. A second four-week course of oral or two to four weeks of IV antibiotics following initial treatment may be necessary in cases involving recurrent arthritis. There is currently no scientific evidence that any other treatment approaches, such as repeated or prolonged courses of therapy, increasing the dosage or combining or alternating antibiotics are any more effective in curing the disease than the standard regimen of shorter duration. Excessive treatment can increase the risk of adverse reactions such as rash, diarrhea, gall-bladder disease and bone marrow damage, and adds unnecessary expense.
How many Lyme disease patients get erythema migrans?
A number of published studies have shown that the proportion of diagnosed Lyme disease patients who present the characteristic rash erythema migrans (EM) is within the range 85 to 95%. The journal Clinical Infectious Diseases (Krause 2002) examines patients suspected of early Lyme disease, babesiosis, and/or anaplasmosis. Among confirmed Lyme disease patients who are not coinfected with other tick-borne diseases, 90% exhibit an EM. Another study published in the New England Journal of Medicine (Gerber 1996) finds that among children (mean age: 7 years) diagnosed with Lyme disease, 89% exhibit an EM. EM distribution on the body is reported as follows:
Table: Frequency of EM occurrence among children diagnosed with LD
| Area on body | Frequency (%) |
| Head or neck | 26 |
| Back | 24 |
| Legs | 17 |
| Abdomen | 9 |
| Arms | 8 |
| Arm pit | 8 |
| Groin | 5 |
| Chest | 3 |
Note: Data obtained from Gerber MA, et al. N Eng J Med 1996; 333: 1270-1274.
The Gerber study also finds that older children (average age about 8 years) are less likely to have an EM on the head and neck compared to younger patients (average age about 6 years). Younger children who are learning to groom themselves may fail to notice ticks attached to these areas. Thus, parents should continue to thoroughly examine their children for ticks.
Results from a large vaccination trial
The results of a large vaccination trial published in the New England Journal of Medicine (Steere 1998) also provide data on the percentage of Lyme disease patients who exhibit an EM. Blood was drawn numerous times over the course of two years from 10,936 subjects living in highly endemic areas of Lyme disease. Among serologically-confirmed symptomatic Lyme disease patients, the percentage exhibiting an EM was 95% during the first year of the study. Lower percentages generated from the paper include patients who did not have symptoms of Lyme disease. Since diagnosis of Lyme disease relies heavily upon identifying clinical symptoms, the 95% figure (as opposed to lower figures) from this paper is more appropriate for use by health care practitioners. To learn more about the Lyme disease vaccine, click here.
Rash recall is not a reliable indicator of presence/absence of an EM
Some low estimates of the percentage of Lyme disease patients who have an EM are calculated by relying on rash recall. A distinction should be made between noticing a rash and actually having a rash. Since the EM rash often occurs in hard-to-see areas on the body, it is quite possible for someone to have an EM and not realize it. Although rash recall may be low (especially among children who are in the process of learning proper grooming habits), this is not a true indicator of whether or not a Lyme disease patient has an EM. According to a recent publication in the New England Journal of Medicine (Wormser 2006), a full-body skin exam should be performed by a physician during the early stages of disease to determine the presence/absence of an EM.
To view pictures of erythema migrans, click here.
Is long-term antibiotic therapy safe?
Some websites indicate that it is necessary to treat Lyme disease with antibiotics for months or even years, sometimes with antibiotics administered intravenously. These assertions simply are not supported by facts. Lyme disease, whatever the stage, is almost always cured by a single course (in some patients with Lyme arthritis a second course may be indicated) of conventional antibiotic treatment (Infectious Diseases Society of America). There is no evidence that either prolonged (more than 4 weeks) or repeated (more than 2 courses) of treatment with antibiotics offers any benefit greater than conventional treatment, and there is substantial evidence that such treatment is associated with significant potential harm. In addition to the substantial financial costs, patients treated with prolonged courses of antibiotics may develop other bacterial infections (which may be life-threatening) with resistant organisms, especially if treatment is with antibiotics administered through an indwelling catheter. In addition, prolonged treatment may select for colonization with antibiotic-resistant "superbugs" that not only may be responsible for infections in the person receiving treatment, but also may be spread to others. Further discussion on long-term antibiotic therapy can be found here: Quackwatch.
Is there a vaccine for Lyme disease?
A Lyme disease vaccine was developed during the early 1990s, and after getting FDA approval in 1998, it was marketed by GlaxoSmithKline under the name LYMErix. The vaccine, however, was pulled from the market in 2002 citing low demand and is no longer available. The last few people vaccinated in 2002 are no longer protected against Lyme disease, as protection was not long lasting. Although there is no human vaccine currently available, there are three Lyme disease vaccines available for dogs, LymeVax, Galaxy Lyme, and Canine Recombinant Lyme. There is no vaccine available for cats.
