Lyme disease (or Lyme borreliosis) is caused by the bacteriaum in the genus Borrelia. In the United States, Lyme disease is most often caused by Borrelia burgdorferi, which is transmitted through the bite of a blacklegged (Ixodes) tick, also known as a deer tick. Besides Lyme disease, tick-borne diseases also include anaplasmosis, babesiosis, Rocky Mountain spotted fever, Colorado tick fever, ehrlichiosis, tularemia, Powassan disease and others.
In the United States, Lyme disease occurs primarily in the Northeast and upper Midwest. About 95% of Lyme disease cases occur in 14 states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, and Wisconsin. The incidence of Lyme disease has recently increased rapidly in the northern New England states of Vermont, New Hampshire and Maine.
Because most tick bites do not result in Lyme disease, antibiotics are not recommended for every tick bite. Most cases of Lyme disease can be prevented or cured with prompt antibiotic treatment. If a preventive antibiotic is needed, a single dose of doxycycline will suffice. To treat active disease, antibiotics are usually given for 2 to 4 weeks. Current guidelines do not recommend longer courses of antibiotic treatment for any stage or complication of Lyme disease.
Lyme disease is the most commonly reported tick-borne disease in the United States. Lyme disease is caused by bacteria in the genus Borrelia (B.), transmitted through the bite of a blacklegged (Ixodes) tick. In the United States, most cases are caused by B. burgdorferi, but recently B. mayonii was also identified as a cause. Worldwide, Lyme disease is caused by B. burgdorferi and other Borrelia species, such as B. afzelii and B. garinii.
B. burgdorferi is a type of bacterium called a spirochete, due to its spiral shape when seen through a microscope. In the United States, B. burgdorferi commonly infects rodents, principally the white-footed mouse, but other small mammals, birds, snakes, lizards, and frogs can be infected as well.
Blacklegged ticks pick up B. burgdorferi when they bite and feed on an infected white-footed mouse or other animal. The spirochete lodges in the intestine of the tick and is transmitted when the tick bites and feeds on a new host.
In the United States, two species of ticks are associated with Lyme disease:
The blacklegged tick has a 2-year life cycle during which it goes through 3 stages of development:
Ticks are active in all seasons, including winter. However, the most critical time for Lyme disease infection is when the nymph stage is most prevalent (May to July). Ticks usually reside on the forest floor or on the tips of grass blades or plant leaves and sense the warmth, vibration, or carbon dioxide given off by a passing animal or person.
Keep in mind that:
Lyme disease is only transmitted through ticks. You cannot catch Lyme disease from a person who has the infection. Lyme disease can also infect dogs (and cats), but it cannot be directly transmitted from a dog to a human, unless an infected tick crawls off a dog and bites a person.
Not all ticks are blacklegged ticks, and not all blacklegged ticks are infected. Most people who are bitten by a tick do not get Lyme disease. Still, Lyme disease and other tick-borne infections should not be taken lightly. It is important to take precautions to avoid tick bites.
Human granulocytic anaplasmosis (HGA) and babesiosis are also transmitted by the deer tick Ixodes scapularis. Although HGA, babesiosis, and Lyme disease are caused by the same kind of tick, these infections are entirely different diseases.
Deer ticks can also transmit deer tick virus, a disease caused by the Powassan virus. In very rare cases, Powassan virus may cause serious brain infection (encephalitis).
New tick-borne diseases, carried by Ixodes ticks as well as other tick species, continue to emerge.
Lyme disease is the most commonly reported insect-borne illness in the United States. About 30,000 confirmed cases of Lyme disease are reported to the U.S. Centers for Disease Control and Prevention (CDC) each year. However, the CDC estimates that the total number of Americans diagnosed annually with Lyme disease is most likely closer to 300,000.
The risk for acquiring Lyme disease reflects the risk of sustaining a tick bite. In general, activities that mostly involve the outdoors (such as working in forested areas, camping, hiking, or gardening) increase the risk of a tick bite and, consequently, of Lyme disease.
Other factors that can increase your risk for tick bites include:
Not every tick bite will cause Lyme disease. In general, there is only a small risk for developing Lyme disease after any one blacklegged tick bite. The risk depends on several factors.
Locations in the United States
Lyme disease was named for a town in Connecticut where the first American cases of the disease were described. Lyme disease has been reported in nearly all U.S. states. However, 95% of Lyme disease cases are concentrated in 14 Northeastern and Midwestern states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, and Wisconsin. The incidence of Lyme disease has recently increased rapidly in the northern New England states of Vermont, New Hampshire and Maine.
Pockets of Lyme disease exist around the world. The disease is common in Europe, particularly in forested areas of middle Europe and Scandinavia. The Borrelia family is also responsible for tick infections in Europe but different species (B. garinii and B. afzelii) are more common and cause slightly different symptoms than the B. burgdorferi spirochete. The infection has also been reported in Russia, China, and Japan.
Blacklegged ticks thrive in grassy areas that have low sunlight and high humidity. Woodlands and fields are prime habitats, but these ticks can also be found in the long grasses adjacent to beaches. The ticks are not confined to rural settings. In suburban areas, they can live in overgrown lawns, ground cover plants, and leaf litter.
The exact time of year for risk depends on a geographic region's seasons and how they affect the tick's breeding cycle. In general, the highest risk for contracting Lyme disease is from late May through July when nymph ticks are active. The lowest risk is from December through March. However, Lyme disease is a year-round concern. Adult ticks can remain active in the winter as long as the temperature is above freezing.
Symptoms of Lyme disease are diverse, can vary from person to person, and can appear and disappear at different times. Symptoms typically occur in 3 stages:
In the majority of cases, the first sign of Lyme disease is the appearance of a bull's-eye rash called erythema migrans (EM), which surrounds the site of the bite. It usually develops about 1 to 2 weeks after the bite, but can appear as soon as 3 days or as late as 1 month after. In some cases, it is never detected. The rash is often accompanied by flu-like symptoms such as fever, headache, fatigue, neck pain and stiffness, and body aches.
The bull's-eye skin rash is considered a classic sign of Lyme disease. It usually appears on the thigh, buttock, or trunk in older children and adults, and on the head or neck in younger children.
The bull's-eye rash may take the following course:
If left untreated, the infection can spread through the bloodstream and lymphatic vessels within weeks to months where it may affect the joints, nervous system, heart, or other organs. Symptoms of early disseminated Lyme disease include:
If not treated with antibiotics, the infection can become established in many areas of the body. Symptoms of late Lyme disease can develop months or years after the initial infection and may include:
Lyme disease, regardless of stage, is a bacterial infection and hence a curable condition. Most people improve after a course of antibiotics. However, in some instances people continue to complain of persistent non-specific symptoms such as fatigue, muscle aches, cognitive problems, and headache that last for years after completing antibiotic treatment for the initial infection.
This pattern of symptoms is referred to as post-Lyme disease syndrome, which can resemble fibromyalgia or chronic fatigue syndrome. People are considered to have this syndrome if they still have symptoms 6 months after treatment. There must also be definitive evidence that a person was originally infected by the B. burgdorferi spirochete.
If there is no documented evidence of a past infection, it is likely that the person never had Lyme disease in the first place, and is experiencing a different type of illness, which is in many cases a rheumatologic or neurologic condition.
Post-Lyme disease syndrome is not a bacterial infection, but possibly an immunologic reaction to a prior (perhaps Borrelia) infection. Antibiotics are not helpful for this condition.
Some people may experience a second or occasionally even a third onset of symptoms (such as the bull's-eye rash) years or even decades after antibiotic treatment. There is no evidence that a prior Lyme infection can relapse. Research indicates that such repeat symptoms are most likely caused by new infections (new tick bites), not relapses from a previous infection. Unlike certain viral infections, an episode of Lyme disease does not protect against future, new infection.
Prompt treatment with antibiotics is very effective in curing Lyme disease in nearly all people. While rare, untreated Lyme disease can spread through the body and lead to complications. People at highest risk for complications are those who go the longest without treatment.
Joint pain is common in all stages of Lyme disease. In early stages of Lyme disease, patients may experience migratory pain in joints, muscles, and tendons. In the later stages of the disease, arthritis localizes to 1 or 2 large joints such as the knee, elbow, shoulder, wrist, ankle, or hip. Knees are the most commonly affected joints.
People with Lyme arthritis usually experience sporadic episodes that last from a few weeks to several months. Fewer than 10% of people develop chronic arthritis, which usually affects a single or only a very few joints.
During the acute infection, Lyme arthritis usually resolves with 2 to 3 weeks of antibiotic treatment. If it does not, prolonged therapy with nonsteroidal anti-inflammatory drugs (NSAIDs), such as naproxen or ibuprofen, is recommended. The anti-malaria drug hydroxychloroquine is also occasionally used, not for its antimalarial properties but for anti-inflammatory effects.
Some health care providers used to prescribe many months of intravenous antibiotics for late stages of Lyme disease. There is no evidence that this is beneficial, and this treatment approach is becoming less frequent. People with difficult-to-treat cases should seek the advice of a rheumatologist or Infections Disease specialist with experience with post-Lyme syndrome.
The medical term for neurological problems caused by the Borrelia burgdorferi organism is neuroborreliosis. These complications are associated with late Lyme disease.
Peripheral Nervous System
The nerves in the peripheral nervous system provide the critical connection between the body's brain and spinal cord, and its limbs and organs. Lyme disease causes various types of nerve damage (neuritis or neuropathies):
Central Nervous System
Lyme disease complications in the central nervous system (CNS) are uncommon but very serious, since this area includes the brain and spinal cord:
When Borrelia infection spreads to the tissues of the heart it can cause inflammation (carditis). Lyme carditis interferes with the heart's electrical conduction signals. The result is "heart block," the stopping of the electrical impulses that keep the heart beating normally. Heart block can occur very suddenly, and can be fatal. Lyme carditis is one of the most serious complications of Lyme disease.
In rare cases, in Europe (but not seen in the United States), Lyme disease can also result in myocarditis, an inflammation of the cardiac muscle. In this uncommon condition, the heart fails to contract as strongly as normal and the person develops congestive heart failure, with accumulation of fluid in the lungs or in other areas of the body.
If Lyme disease spreads throughout the body, it can affect other organs. Lyme disease may rarely manifest as hepatitis (liver), hearing loss (ears), or keratitis (eyes).
In rare cases, Lyme disease acquired during pregnancy can lead to infection of the placenta and possible miscarriage or stillbirth. Studies indicate that pregnant women infected with Lyme disease can safely be treated with antibiotics without endangering the fetus.
Lyme disease is usually diagnosed based on symptoms and evidence of possible exposure to ticks. Your health care provider may diagnose you with Lyme disease if you:
If these criteria are met, treatment is often started without confirming the diagnosis with laboratory tests. Lab tests for Lyme disease are not recommended for people who do not exhibit any of these symptoms.
Blood tests for detecting antibodies to B. burgdorferi are most reliable several weeks after infection has occurred and are rarely of value during the first 7 to 10 days of illness. During these initial days of infection, these tests can give false negative results (showing no evidence of the disease even though the person actually has it).
Most authorities, including the CDC, recommend a 2-step testing process for Lyme disease:
The CDC recommends only these tests. Although many other tests are widely advertised, they do not have enough scientific evidence to support their use.
The polymerase chain reaction (PCR) test detects the DNA of the bacteria that causes Lyme disease. It is sometimes used for select individuals who have neurological symptoms or Lyme arthritis. The PCR test is performed on spinal fluid collected from a lumbar puncture (spinal tap) or synovial fluid (collected from an affected joint). This test is generally available only in research settings and for most people, standard 2-step tests are preferred.
Many other infections and medical conditions can produce fever, headache, muscle aches, and fatigue, including a very wide variety of common, generally benign viral illnesses. They can also produce some of the neurologic or cardiac features characteristic of early Lyme disease. The same tick that causes Lyme disease can also transmit other infections.
Co-Infections Transmitted by the Ixodes Tick
Babesiosis, Rocky Mountain Spotted Fever (RMSF), and human granulocytic anaplasmosis (HGA) are transmitted by the same tick that carries Lyme disease. People may be co-infected with one or more of these infections, all of which can cause flu-like symptoms. If these symptoms persist and there is no rash, it is less likely that Lyme disease is present.
Other Tick-Borne Infections
A number of other tick-borne diseases may resemble Lyme disease. The most important of these is southern tick-associated rash illness (STARI), which is caused by the bite of the Lone star tick, usually in southern and Southeastern parts of the United States. It causes a rash very similar to Lyme disease. The bacterium responsible for STARI (if there is one) remains unknown, but may be B. lonestari.
Allergic Reactions and Insect Bites
If a rash appears hours (rather than days) after a tick bite, it is most likely an allergic reaction to the tick, not a symptom of Lyme disease. An allergic rash may also be circular, like that from Lyme disease. In addition, not every rash seen in regions where Lyme disease is common is caused by a tick. The bites of many other insects such as spiders can cause a skin reaction, but they do not resemble the bull's-eye rash of Lyme disease.
Fatigue and joint and muscle aches are common symptoms of post-Lyme disease syndrome. These symptoms can also be caused by other conditions, including mononucleosis, chronic fatigue syndrome, and fibromyalgia. Early neurologic symptoms of Lyme disease (headache, stiff neck, and fatigue) may be mistaken for viral meningitis.
Antibiotics are the drugs used for treating all phases of Lyme disease. In nearly all cases they can cure Lyme disease, even in later stages.
According to guidelines from the Infectious Diseases Society of America (IDSA), people bitten by deer ticks should not routinely receive antibiotics to prevent the disease, especially if Lyme disease is not common in that area. In areas where Lyme disease is prevalent, a single dose of an antibiotic is commonly administered after a tick bite.
A single dose of the antibiotic doxycycline may be given if:
In general, the risk of developing Lyme disease after being bitten by a tick is only 1% to 3%. However, if you have an attached tick or have removed it yourself, be sure to inform your health care provider. Also let your provider know if you develop a bull's-eye rash or any flu-like symptoms in the first 30 days following a tick bite.
The early stages of Lyme disease usually include the bull's-eye rash (erythema migrans) and flu-like symptoms of chills and fever, fatigue, muscle pain, and headache. In rare cases, people develop an abnormal heartbeat (Lyme carditis).
All of these conditions are treated with 14 to 28 days antibiotics courses. The exact number of days depends on the drug used and the person's response to it. Antibiotics for treating Lyme disease generally include:
Other types of antibiotics, such as macrolides like azithromycin and clarithromycin, are not recommended for first-line therapy.
Antibiotic Side Effects
The most common side effects of nearly all antibiotics are gastrointestinal problems, including cramps, nausea, vomiting, and diarrhea. Doxycycline can cause sunlight sensitivity and increase the chance you will get a rash due to sun exposure.
Allergic reactions can occur with all antibiotics, but are more common with medications derived from penicillin or sulfa. A reaction could be as minor as a mild skin rash, but could also be severe or life-threatening. Some drugs, including certain over-the-counter medications, interact with antibiotics. Be sure to let your provider know all medications you are taking.
Most cases of Lyme disease involve a rash and flu-like symptoms that resolve within 1 month of antibiotic treatment. However, some people go on to develop late-stage Lyme disease, which includes Lyme arthritis and neurologic Lyme disease.
Slightly more than half of people infected with B. burgdorferi develop Lyme arthritis. About 10% to 20 % of people develop neurologic Lyme disease. A very small percentage may develop acrodermatitis chronica atrophicans, a serious type of skin inflammation occurring more frequently in Europe. These conditions are treated for up to 28 days with antibiotic therapy.
If arthritis symptoms persist for several months, a second 2 to 4 week course of antibiotics may be recommended. Oral antibiotics (doxycycline, amoxicillin, or cefuroxime) are used for Lyme arthritis and acrodermatitis chronica atrophicans.
In rare cases, people with arthritis may need intravenous antibiotics. A 2 to 4 week course of intravenous ceftriaxone is used for treating severe cases of neurological Lyme disease. For milder cases, 2 to 4 weeks of oral doxycycline is an effective option.
In about 5% of cases, symptoms persist after treatment. This condition is referred to as post-Lyme disease syndrome. The treatment of post-Lyme disease syndrome is controversial. Most experts do not recommend continuing antibiotic therapy beyond 30 days. Scientific studies do not show evidence that the benefits of long-term antibiotic treatment outweigh its risks.
Long-term antibiotic treatment can lead to a serious and difficult-to-treat infection with Clostridium difficile, and can also cause a person to become allergic to the antibiotic. In addition, long-term antibiotic treatment carries its own serious risks, such as the colonization of antibiotic-resistant super bugs.
Experimental and alternative remedies are not recommended. However, some people may benefit from learning pain control and cognitive behavioral techniques to help them cope with and manage their symptoms.
Some people use vitamin B complex, omega-3 and omega-6 fatty acids (found in primrose oil and fish oils), and magnesium supplements to help relieve symptoms. No evidence suggests that they are beneficial. Always check with your provider before using any herbal remedies or dietary supplements.
Newsletters and Internet sites have cropped up in recent years advertising untested treatments to people with symptoms of post-Lyme disease syndrome or so-called "chronic Lyme disease" who are frustrated with standard medical treatment. Some remedies may be dangerous and ineffective.
The FDA has warned people not to use an alternative medicine product called bismacine (also known as chromacine). This injectable product contains high amounts of bismuth, a heavy metal that can be poisonous. People who have taken bismacine have experienced heart and kidney failure, and at least one death has been reported. Although some people claim that bismacine can help treat Lyme disease, it is not approved or recommended for the treatment of any illness or condition.
Everyone should avoid specific tick-infested areas, including tall grass, woods, and bushes where ticks tend to congregate. If you are going to be in these areas, it is important to take preventive measures.
The CDC recommends:
Anyone who walks or camps in the woods should wear tick-protective clothing, including:
After being outdoors, you should run your clothes through a dryer at high temperature for at least 10 minutes. If washing is required first, use hot water or follow a cold water wash with extended dryer cycles (low heat for 90 minutes or high heat for 60 minutes).
The best insect repellants for protecting against ticks are:
Permethrin is considered the overall best tick repellant. It is applied to clothes, not the skin. Ticks exposed to permethrin treated clothes either immediately fall off or die if they linger. You can spray or soak clothes with solutions that contain 0.5% permethrin and then let them air dry for several hours before wearing. (It is especially important to treat shoes and socks.) The clothing will remain protected for 5 or 6 washes. You can also buy pre-treated tick repellant clothes that will retain the permethrin through 70 washes.
The chemical DEET is very effective against mosquitoes, although less so against ticks. Still, applying DEET to exposed skin can help provide protection against ticks (especially if you also wear permethrin-treated clothes.)
Concentrations range from 10% to 98%. The concentration level determines the duration of protection. The CDC recommends using repellants that contain a DEET concentration of 20 to 30%. (A 30% concentration supplies protection for 5 hours.) DEET is approved for both adults and children, but it should not be used on infants younger than 2 months.
When applying DEET or other insect repellant products:
Picaridin is an alternative chemical to DEET. It works better than DEET for biting flies, but may be less effective than DEET for tick protection. Some advantages of picaridin compared to DEET are that it is odorless and does not stain or damage fabrics.
Picaridin is available in concentrations ranging from 5% to 20%. Stronger concentrations can last up to 8 hours. Picaridin is safe for adults and children but, like all insect repellants, should not be applied on children younger than 2 months.
In most cases, ticks begin transmitting the Lyme disease spirochete only after 36 to 48 hours of attachment, however the precise minimum time is not known. Removing a tick within 24 to 48 hours can reduce your chance of contracting Lyme disease. The following tips are important for self-inspection:
If an attached tick is discovered, there is no reason to panic. A very small percentage of ticks are actually infected (between 1% to 5% even in areas where Lyme disease is prevalent), and not everyone who is bitten by a tick will get Lyme disease.
Do not put a hot match to the tick or try to smother it with petroleum jelly, nail polish, or other substances. This only prolongs exposure time and may cause the tick to eject the Lyme spirochete into the body.
The following is the safest and most effective way to remove an attached tick:
To decrease the tick population around your yard:
Since dogs, cats, and even horses can get Lyme disease, inspect pets for ticks regularly. Repellents and acaricides (products that kill ticks) are available for pets. Cats may be extremely sensitive to some products. Discuss with your veterinarian the best tick prevention product for your pet. Lyme disease vaccines are available for dogs, but they do not offer total protection and veterinarians vary in their use of this vaccine. There is currently no Lyme disease vaccine for humans.
Arvikar SL, Steere AC. Diagnosis and treatment of Lyme arthritis. Infect Dis Clin North Am. 2015;29(2):269-280. PMID: 25999223 www.ncbi.nlm.nih.gov/pubmed/25999223.
Berende A, ter Hofstede HJ, Vos FJ, et al. Randomized Trial of Longer-Term Therapy for Symptoms Attributed to Lyme Disease. N Engl J Med. 2016;374(13):1209-1220. PMID: 27028911 www.ncbi.nlm.nih.gov/pubmed/27028911.
Bockenstedt LK, Wormser GP. Review: unraveling Lyme disease. Arthritis Rheumatol. 2014;66(9):2313-2323. PMID: 24965960 www.ncbi.nlm.nih.gov/pubmed/24965960.
Cadavid D, Auwaerter PG, Rumbaugh J, Gelderblom H. Antibiotics for the neurological complications of Lyme disease. Cochrane Database Syst Rev. 2016;12:CD006978. PMID: 27931077 www.ncbi.nlm.nih.gov/pubmed/27931077.
Centers for Disease Control and Prevention. Tickborne diseases of the United States: A Reference Manual for Health Care Providers. Fourth edition (2017). www.cdc.gov/lyme/resources/tickbornediseases.pdf. Accessed Jun 19, 2017.
Chowdri HR, Gugliotta JL, Berardi VP, et al. Borrelia miyamotoi infection presenting as human granulocytic anaplasmosis: a case report. Ann Intern Med. 2013;159(1):21-27. PMID: 23817701 www.ncbi.nlm.nih.gov/pubmed/23817701.
Clark RP, Hu LT. Prevention of lyme disease and other tick-borne infections. Infect Dis Clin North Am. 2008;22(3):381-396, vii. PMID: 18755380 www.ncbi.nlm.nih.gov/pubmed/18755380.
Forrester JD, Meiman J, Mullins J, et al. Notes from the field: update on Lyme carditis, groups at high risk, and frequency of associated sudden cardiac death--United States. MMWR Morb Mortal Wkly Rep. 2014;63(43):982-983. PMID: 25356607 www.ncbi.nlm.nih.gov/pubmed/25356607.
Halperin JJ. Nervous system Lyme disease. Infect Dis Clin North Am. 2015;29(2):241-253. PMID: 25999221 www.ncbi.nlm.nih.gov/pubmed/25999221.
Hu LT. In the clinic. Lyme disease. Ann Intern Med. 2012;157(3):ITC2-2 - ITC2-16. PMID: 22868858 www.ncbi.nlm.nih.gov/pubmed/22868858.
Lantos PM. Chronic Lyme disease. Infect Dis Clin North Am. 2015;29(2):325-340. PMID: 25999227 www.ncbi.nlm.nih.gov/pubmed/25999227.
Nelder MP, Russell CB, Sheehan NJ, et al. Human pathogens associated with the blacklegged tick Ixodes scapularis: a systematic review. Parasit Vectors. 2016;9:265. PMID: 27151067 www.ncbi.nlm.nih.gov/pubmed/27151067.
Pritt BS, Mead PS, Johnson DK, et al. Identification of a novel pathogenic Borrelia species causing Lyme borreliosis with unusually high spirochaetaemia: a descriptive study. Lancet Infect Dis. 2016;16(5):556-564. PMID: 26856777 www.ncbi.nlm.nih.gov/pubmed/26856777.
Robinson ML, Kobayashi T, Higgins Y, Calkins H, Melia MT. Lyme carditis. Infect Dis Clin North Am. 2015;29(2):255-268. PMID: 25999222 www.ncbi.nlm.nih.gov/pubmed/25999222.
Sanchez E, Vannier E, Wormser GP, Hu LT. Diagnosis, treatment, and prevention of Lyme disease, Human Granulocytic Anaplasmosis, and Babesiosis: a review. JAMA. 2016;315(16):1767-1777. PMID: 27115378 www.ncbi.nlm.nih.gov/pubmed/27115378.
Stanek G, Wormser GP, Gray J, Strle F. Lyme borreliosis. Lancet. 2012;379(9814):461-473. PMID: 21903253 www.ncbi.nlm.nih.gov/pubmed/21903253.
Steere AC. Lyme disease (Lyme Borreliosis) due to Borrelia burgdorferi. In: Bennett JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th edition. Philadelphia, PA: Elsevier Saunders; 2015:chap 243.
Vannier E, Krause PJ. Human babesiosis. N Engl J Med. 2012;366(25):2397-2407. PMID: 22716978 www.ncbi.nlm.nih.gov/pubmed/22716978.
Wormser GP. Lyme disease. In Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 321.
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.