Lyme disease and related tick-borne infections

Causes

Lyme disease (or Lyme borreliosis) is caused by bacteria 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.

Risk Factors

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.

• Anyone exposed to deer ticks is at risk for Lyme disease. These ticks thrive in grassy areas that have low sunlight and high humidity.
• Immature (nymph) ticks are the main transmitters of Lyme disease. Their small size makes them harder to spot than adults. Nymph ticks are most active during the spring and summer months. Consequently, the risk for acquiring Lyme disease tends to be higher during these seasons. However, Lyme disease can be acquired at any time during the year if the ticks are active.

Prevention

• Avoid tick-infested areas such as tall grass, woods, and bushes.
• Wear long pants (and tuck them into your socks) and long sleeves when you walk through these areas.
• Wear light-colored clothes to make spotting ticks easier.
• Use an insect repellent on your exposed skin and clothes, such as DEET or picaridin. Spray your clothes (not your skin) with permethrin.
• Check for ticks when you return home. Removing infected ticks within 24 to 48 hours of attachment significantly reduces the risk of developing Lyme disease.
• Washing (shower or bath) soon after being out also can dislodge ticks before they transmit infection.

Symptoms

• A bull's-eye rash (erythema migrans) at the site of the tick bite is the most definitive sign of Lyme disease. This rash usually develops 1 to 2 weeks after a tick bite.
• Other symptoms may accompany the rash, such as joint pain, fever, chills, fatigue, or flu-like symptoms.
• If Lyme disease is not treated, there is a chance that more severe symptoms and complications can occur. These include arthritis, neurologic symptoms, or heart problems.

Treatment

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 but only if given in the first 72 hours after the tick has attached. 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.

Borrelia Burgdorferi and White-Footed Mice

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 (Ixodes) Ticks

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:

• In the U.S. Northeast and North Central states, the blacklegged tick, Ixodes scapularis, also known as the deer tick, is the principal vector (vector is the insect that carries bacteria from one animal to another).
• In the U.S. Northwest states, it is the blacklegged tick Ixodes pacificus.
• Other species of tick are not known to transmit Lyme disease.

The Cycle of Infection

The blacklegged tick has a 2-year life cycle during which it goes through 3 stages of development:

• Egg. Adult females lay eggs during the spring of year 1. Eggs are deposited usually on the ground in the area where the female detached from its host.
• Larva Stage. In spring and summer of year 1, 6-legged larvae hatch from eggs. They take their first meal from a mouse, bird, or other small animal. This is when larvae can first acquire the B. burgdorferi spirochete but they do not transmit it at this stage. After feeding, the larvae fall off their hosts and molt into nymphs, which become dormant for the fall and winter of year 1.
• Nymph Stage. In the spring and summer of year 2, the 8-legged nymph ticks wake up and begin to feed on wild animals (mice, chipmunks, and birds), domestic animals (dogs), or humans. Peak activity is usually from late May through July, although this can vary depending on climate. Most cases of Lyme disease are transmitted by nymphs.
• Adult Stage. In the fall of year 2, the nymphs become 8-legged adults. Only the adult female takes a blood meal. Adult female ticks may also transmit Lyme disease. For their third and final meal, female ticks seek a larger animal. After feeding, they mate with males, drop off the host, lay eggs, and then die. White-tailed deer are the main hosts (and means of transportation) for adult ticks. Female ticks feed on deer, while male ticks attach themselves to deer to wait for the females.

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:

• Nymph ticks are only about the size of a poppy seed. They are very difficult to spot and are responsible for the majority of Lyme disease cases.
• Adult ticks can be as large as a raisin after feeding, so they are easier to see. In addition, they usually prefer to dine on the blood of white-tailed deer rather than humans.
• A tick feeds for several days while being embedded in the skin. After this time, it falls off. The tick's bite is painless. Generally, if you feel an insect sting, it was not from a tick. Only about half of people with Lyme disease recall being bitten.
• Once a tick is attached, it may take up to 36 to 48 hours for the spirochete to be transmitted to the host. If you can find and remove the tick while it is still attached but before it has become engorged with blood, you can significantly reduce your risk for Lyme disease.

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.

Other Infections Carried by the Ixodes Tick

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.

General Risk Factors

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 using tick repellant (permethrin for clothes and DEET for bare skin).
• Wearing dark-colored clothing (choose light-colored clothing so you can spot ticks more easily).
• Not doing tick checks (check your skin and clothes while outside, and do a complete body check for ticks when you come back inside).

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.

• The longer the tick has fed, the greater the risk. The exact amount of time necessary for an attached tick to transmit the Lyme disease bacteria is not known. However removal of the tick within the first 24 to 48 hours of attachment significantly reduces the risk.
• Nymph ticks carry a greater risk than adult ticks, and they are often too small to be detected (about the size of a pinhead). Nymph ticks are active from May to July.
• Although nymph ticks are dormant in the winter, adult ticks are active during milder winter days or in indoor locations such as barns. It is best to take precautions during all seasons.
• Only ticks that are at least partially swollen when removed pose any significant risk. The swelling suggests that they have been feeding for a prolonged period.

Geographic Locations

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.

Worldwide Locations

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.

High-Risk Landscapes

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.

Time of Year

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:

• Stage 1 is early localized Lyme disease. It occurs 3 to 30 days after the tick bite when the infection has not yet spread throughout the body.
• Stage 2 is early disseminated Lyme disease. It occurs weeks to months after the tick bite when the bacteria have begun to spread throughout the body.
• Stage 3 is late Lyme disease. It occurs months to years after the tick bite when the bacteria have spread to various parts of the body.

Early Localized Lyme Disease

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:

• It can first appear as a pimple-like spot that expands over the next few days into a purplish circle. The circle may reach up to 6 inches in diameter with a deeper red rim. In some cases the ring is incomplete, forming an arc rather than a full circle.
• The center of the rash often clears or may turn bluish. Or secondary concentric rings may develop within the original ring, creating the bull's-eye pattern. Over the next several days or 1 to 2 weeks, the circular rash may grow to as large as 20 inches across
• The rash has a burning (not itching) sensation. On darker-skinned people, the rash may resemble a bruise. In most people, the rash fades completely after 3 to 4 weeks. Secondary rashes may appear during the later stages of disease.

Early Disseminated Lyme Disease

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:

• Multiple bull's eye rashes on various parts of the body.
• Severe fatigue
• Flu-like symptoms
• Joint pain
• Numbness or nerve pain
• Weakness or paralysis in the muscles of the face
• Stiff and painful neck, which may be a sign of Lyme meningitis
• Heart problems (Lyme carditis); symptoms include light-headedness, heart palpitations, shortness of breath, chest pain, or fainting

Late Lyme Disease

If not treated with antibiotics, the infection can become established in certain areas of the body. Symptoms of late Lyme disease can develop months or years after the initial infection and may include:

• Joint pain and swelling (Lyme arthritis)
• Nerve damage resulting in weakness, pain, numbness, and tingling in hands and feet (peripheral neuropathy)
• Neurological problems (confusion, memory loss, difficulty concentrating, or speech problems)

Post-Lyme Disease Syndrome

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 months or even 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 Complications (Lyme Arthritis)

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.

When treated, Lyme arthritis usually resolves with 2 to 3 weeks of starting antibiotics. 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 it can be very harmful therefore this treatment approach is highly discouraged. People with difficult-to-treat cases should seek the advice of a rheumatologist or infectious disease specialist with experience with Lyme complications and post-Lyme syndrome.

Neurologic Complications (Neuroborreliosis)

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):

• Peripheral neuropathy is nerve damage that disrupts signals from the brain or spinal cord to the limbs and other parts of the body. People with peripheral neuropathy may experience numbness, weakness, pain (often described as a "burning" or "shooting" pain) or tingling in the hands and feet.
• Cranial neurosis can result in facial palsy, numbness, dizziness, double vision, or hearing changes.
• Radiculoneuropathy occurs when Lyme disease affects the nerve roots that leave the spinal cord. Symptoms include stabbing or burning pains that shoot across the limbs or the torso. Muscle weakness can also occur.

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:

• Meningitis can occur if the infection spreads to the membranes that surround the brain and spinal cord (the meninges). Symptoms include severe headache, neck stiffness and pain, and sensitivity to light.
• Encephalomyelitis is inflammation in the brain and spinal cord, which damages the protective sheath that covers nerve fibers (myelin). Symptoms include headache, confusion, alteration in level of consciousness, difficulty with words and speech, and muscle weakness. It may be misdiagnosed as multiple sclerosis.
• Lyme encephalopathy refers to cognitive and memory problems. Symptoms include "brain fog," problems with short- and long-term memory, difficulty with word recall, slow thought processing, and general feelings of mental impairment.

Heart Complications (Lyme Carditis)

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.

Other Organ Complications

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).

Pregnancy and Lyme Disease

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:

• Have the classic bull's-eye rash (erythema migrans)
• Have other symptoms, such as headache, joint aches, malaise, or flu-like symptoms
• Have recently spent time in a tick infested area

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 with a classic rash for erythema migrans or for those who do not exhibit any of these symptoms.

Blood Tests for Antibodies

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:

• EIA Test. The first test used is an enzyme immunoassay (EIA). The EIA measures IgM and IgG antibodies to the B. burgdorferi spirochete. Positive results from this test still require confirmation with a Western blot test, since the EIA test (especially the IgM component) is often positive even when there has been no infection. Negative results do not require further testing.
• Western Blot or second EIA test. If the EIA test is positive or uncertain, it is followed by the Western blot test. This test is more accurate and is very helpful in confirming the diagnosis but is more expensive and takes longer to complete. The Western blot creates a visual graph showing bands of IgM or IgG antibodies that laboratories use to interpret the immune response. More recently, recommendations have changed to allow for a second EIA in place of the confirmatory Western blot (see below).
• V1sE (C6 peptide ELISA). This newer FDA-approved test detects a specific component within the EIA IgG antibodies and is being increasingly used instead of the Western Blot to confirm a positive EIA test. Since it is less expensive and more rapidly completed, it may ultimately replace the Western Blot test.

The CDC recommends only these types of tests.

In 2019 the FDA has approved a new testing algorithm involving running two different Lyme EIAs, either at the same time or one after the other, for confirmation. This double EIA method produces earlier positive results after infection, is more easily interpreted, and is more easily run by labs. It is also as accurate as using EIA followed by confirmatory Western Blot. Although many other tests are widely advertised, they do not have enough scientific evidence to support their use and should be avoided, as their interpretation is often dubious.

Polymerase Chain Reaction (PCR) Test

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.

Ruling Out Other Diseases

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.

Other Diseases

Fatigue and joint and muscle aches are common symptoms of post-Lyme disease syndrome. These symptoms can also be caused by many other conditions, including depression, 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.

Preventive Antibiotics After a Tick Bite

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:

• At least 20% of ticks in the geographic area are infected with B. burgdorferi.
• The tick is still attached to the person and is positively identified as a species of Ixodes tick that carries the Lyme disease B. burgdorferi spirochete.
• Doxycycline treatment can be given within 72 hours of the tick bite.
• It is safe for the person to receive doxycycline. (This drug should not be given to pregnant women or children younger than 8 years of age.)

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.

Treating Early Stage Lyme Disease

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:

• Doxycycline. This antibiotic is effective against both Lyme disease and human granulocytic anaplasmosis (HGA). It is the standard antibiotic for anyone over 8 years old, except for pregnant women. It is a form of tetracycline and can discolor teeth and inhibit bone growth in young children. It can also cause birth defects if used during pregnancy.
• Amoxicillin. This type of penicillin is probably the best antibiotic for pregnant women. Some people are allergic to penicillin and strains of Lyme bacteria are emerging that are resistant to it.
• Cefuroxime (Ceftin). This cephalosporin antibiotic is an alternative treatment for young children and for adults with penicillin allergy.
• Intravenous ceftriaxone or cefotaxime. Intravenous infusions of one of these cephalosporin antibiotics may be warranted if there are signs of infection in the central nervous system (the brain or spinal region) or heart.

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.

Treating Late Stage Lyme Disease

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.

Untreated, slightly more than half of people infected with B. burgdorferi will 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.

Treating Post-Lyme Disease Syndrome

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 any 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 in the intestines 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 side effects and the colonization of antibiotic-resistant germs.

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.

Herbs and Supplements

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. In addition, medical providers around the U.S. have been sanctioned or even lost their license to practice medicine for giving inappropriate and dangerous treatments for "Lyme Disease", often with no proper confirmatory testing or for symptoms that are not treatable with antibiotics.

Bismacine

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:

• Walk in the center of trails away from vegetation.
• Use tick repellent. Apply permethrin to your clothes and DEET to your exposed skin for the most effective protection. (Be sure to completely wash off the DEET when you return home.)
• Do routine checks for ticks. Removal of ticks within 24 to 48 hours of attachment substantially reduces the likelihood of Lyme disease transmission.
• Contact your health care provider if you find an attached tick. If your provider thinks you are at risk for Lyme disease, a single dose of antibiotics given within 72 hours of tick removal can help prevent infection.
• Tick-proof your property. Remove brush and leaves in your yard and place wood chip around the perimeter.

Protective Clothing

Anyone who walks or camps in the woods should wear tick-protective clothing, including:

• Light-colored clothing that makes it easier to spot ticks
• Long-sleeved shirts and long pants with cuffs tucked into shoes or socks (ticks cannot jump or fly but they do crawl upward)
• High boots, preferably rubber
• For the best protection, wear clothes and shoes pretreated with permethrin

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).

Insect Repellents

The best insect repellants for protecting against ticks are:

• Permethrin (for clothing)
• DEET, picaridin, or IR3535 (for exposed skin)

Permethrin

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.

DEET

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:

• Do not apply directly to the face. Apply first to your hands, and then your face.
• Do not apply over any cuts, wounds, or irritated skin.
• Do not apply to skin covered by clothing.
• Do not apply to the hands or near the eyes or mouth of young children. Adults should apply repellent to children; do not let children apply it themselves.
• Thoroughly wash any treated skin after returning home. (DEET can result in serious side effects if excessive amounts remain in prolonged contact with skin.)
• DEET can be applied to clothes, but be aware that it can damage some synthetic fabrics.

Picaridin

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.

Tick Check and Tick Removal

Tick Check

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:

• Nymph ticks are very small and may resemble poppy seeds, freckles, or scabs. Adult ticks may resemble raisins.
• People spending time in tick-infested locations should inspect themselves several times a day, including at bedtime.
• Check non-exposed areas, such as the back of the knee, as well as exposed areas. Someone else should check the scalp, back of the neck, and other difficult to reach areas. Parents should check children.
• After coming from outdoors, take a shower. It may help wash off unattached ticks, gives you an opportunity for a complete tick check, and will remove any remaining DEET.
• Check clothing as well as skin. A tick on clothes can be hidden in folds or creases.

Tick Removal

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:

• Grasp the tick's mouth area with clean, fine-tipped tweezers as close to the skin as possible. (Take care not to handle it with bare fingers as this can also spread infection.)
• Next, pull upward with a steady even pressure. Do not twist, crush, or squeeze the body area of the tick, because this region contains the infectious organism. In fact, do not be alarmed if some of the mouth parts remain in the skin. They are not infectious.
• Put the tick in a jar or container of alcohol, which will kill it. You can place a piece of adhesive tape on the top of the tick and fold it over, without touching the insect. Then simply throw it away. Tape is also effective for trapping a tick that has not yet attached to the skin. Do not crush a tick with your fingers.
• Once the tick is removed, wash the bite area with soap and water or with an antiseptic to destroy any contaminating microorganisms. Wash hands as well.

Protecting Property from Tick Infestation

To decrease the tick population around your yard:

• Clear the yard regularly by raking leaves, trimming bushes, pruning low-lying branches, mowing lawn.
• Create a 3-foot wide barrier around the perimeter of your lawn with wood chips, gravel, or mulch.
• Place cardboard tubes stuffed with permethrin-treated cotton in places (woodpiles, stone walls) where mice can find them. These tubes are available in hardware stores. Mice collect the cotton for lining their nests; the pesticide on the cotton kills any immature ticks that feed on the mice. For best results, do several tube applications from early to late summer.
• Erect fences or use repellants or deer-resistant plants to keep deer away.
• Consider spraying once a year a small amount of tick-killing insecticide such as permethrin or bifenthrin around the perimeter of your yard. To avoid health and environmental risks, consult a licensed professional experienced with tick control.

Protecting Pets

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.

• Centers for Disease Control and Prevention -- www.cdc.gov/lyme
• National Institute of Allergy and Infectious Diseases -- www.niaid.nih.gov
• Infectious Diseases Society of America -- www.idsociety.org
• American Lyme Disease Foundation -- www.aldf.com
• American College of Rheumatology -- rheumatology.org
• The Arthritis Foundation -- www.arthritis.org
• Tick Encounter Resource Center -- www.tickencounter.org