Lyme disease

Description: Alternative Names: Borreliosis. A subacute inflammatory disorder caused by infection with Borrelia burgdorferi, a nonpyogenic spirochete transmitted by Ixodes scapularis, the deer tick, in the eastern U.S. and I. pacificus, the western black-legged tick, in the western U.S.; the characteristic skin lesion, erythema chronicum migrans, is usually preceded or accompanied by fever, malaise, fatigue, headache, and stiff neck; neurologic, cardiac, or articular manifestations may occur weeks to months later. Tick nymphs are thought to be responsible for about 90% of transmission to human beings. Nymphs and larvae feed especially on the white-footed mouse, Peromyscus leucopus, while the preferred host of adults is the deer. Infected reservoir animals and ticks do not become ill. Residual articular or neurologic symptoms, which may persist for months or years after the initial infection, probably represent an immune response to the organism. Variations in clinical features or severity from one patient to another may be due to inborn variations in immune response, perhaps linked to the human lymphocytic antigen system. Syn: Lyme borreliosis. Lyme disease is a bacterial infection transmitted by a tick. Lyme disease was first recognized in 1975, after researchers investigated why unusually large numbers of children were being diagnosed with juvenile rheumatoid arthritis in Lyme, Conn., and two neighboring towns. The investigators discovered that most of the affected children lived near wooded areas likely to harbor ticks. They also found that the children's first symptoms typically started in the summer months coinciding with the height of the tick season. Several of the patients reported having a peculiar skin rash just before developing arthritis symptoms, and many also recalled being bitten by a tick at the rash site. Further investigations resulted in the discovery that tiny deer ticks infected with a spiral-shaped bacterium or spirochete (which was later named Borrelia burgdorferi) were responsible for the outbreak of arthritis in Lyme. Ordinary "wood ticks" and "dog ticks" do not carry the infection. The ticks most commonly infected with B. burgdorferi usually feed and mate on deer during part of their life cycle. The recent growth of the deer population in the northeast and the building of suburban developments in rural areas where deer ticks are commonly found have probably contributed to the increasing number of people with the disease. The number of reported cases of Lyme disease, as well as the number of geographic areas in which it is found, has been increasing. Lyme disease has been reported in nearly all states in this country, although most cases are concentrated in the coastal northeast, Mid-Atlantic States, Wisconsin and Minnesota, and northern California. Lyme disease is also found in large areas of Asia and Europe. Recent reports suggest that it is present in South America, too. In addition to causing arthritis, Lyme disease can also cause heart, brain and nerve problems. Lyme disease is the most common vector-borne disease in the United States. It is caused by the spirochetal bacterium Borrelia burgdorferi, and it is transmitted to humans by the "bites" of certain kinds of ticks. Lyme disease cannot be transmitted from an infected person to another person. The infection can involve multiple organ systems and has myriad manifestations, but is rarely, if ever, fatal. Lyme disease has a wide distribution in northern temperate regions of the world. In the United States, the highest incidence occurs in the Northeast, from Massachusetts to Maryland and the North-central states, especially Wisconsin and Minnesota. In 2002, more than 23,000 cases of Lyme disease were reported in the U.S., the highest number ever reported. This increase could be caused by an increase in human contact with infected ticks and enhanced reporting of cases. Ten states have consistently reported an incidence of Lyme disease higher than the national average: Connecticut, Delaware, Maryland, Massachusetts, Minnesota, New Jersey, New York, Pennsylvania, Rhode Island and Wisconsin. During 2003-2005, 64,382 Lyme disease cases were reported to CDC, of which 59,770 cases (93%) were reported from these 10 states. Similar data was reported in 2006 (see map below). Because of media coverage, Lyme disease has a higher profile than its occurrence warrants. Fewer than 18,000 cases are confirmed annually in the U.S. It is generally a benign, self-limited disease, even when untreated. Antibody studies in endemic areas suggest that as many as 50% of persons who contract the infection never show symptoms. The case fatality rate is virtually zero. The diagnosis is essentially clinical. Serologic tests for antibody to B. burgdorferi are notoriously poor in both sensitivity and specificity. In nonendemic areas, false-positive test results statistically outnumber true positives. IgM antibody appears and peaks relatively late, so that one-half of patients are seronegative during the first month following appearance of the rash. Antibiotic treatment administered early can alter or prevent the expected acute immune response. IgG antibody persists for months or years after infection and hence affords no help in diagnosing acute disease. Given the nonspecific and variable clinical picture and the unreliability of laboratory diagnostic measures, it is inevitable that many cases of Lyme disease are missed, and that, conversely, the diagnosis is often wrongly made. A study assessing the costs of misdiagnosis of Lyme disease found that 60% of patients referred to a Lyme disease clinic had never had the disease and another 19% had a history of infection but no current disease. The drug of choice is doxycycline administered orally for several weeks. Amoxicillin is the standard alternative for children and pregnant patients. Recovery does not confer immunity to future attacks; in fact, in highly endemic areas, the reinfection rate may be as high as 20%. Infectious disease authorities do not recommend antibiotic prophylaxis after a tick bite, even in highly endemic areas, nor do they countenance treatment of asymptomatic persons who have serologic evidence of past infection. A vaccine consisting of outer surface protein A (OspA) of B. burgdorferi synthesized by a nonvirulent strain of recombinant Escherichia coli was released in 1998. Antibody induced by the vaccine enters a feeding tick and binds any spirochetes present, preventing their mobilization. Three doses of the vaccine administered over a 12-month period confer about 80% protection against Lyme disease. The vaccine is not approved for persons under age 15 and is recommended only for those living or working in highly endemic areas. Symptoms: One sign of Lyme disease is a round, red rash that spreads at the site of a tick bite. This rash can get very large. Flu-like symptoms are also very common. People in the early stages of Lyme disease may feel very tired and have headaches, sore muscles and joints, and a fever. These symptoms can start at any time, from 3 days up to a month after you have been bitten. Some people don't have any symptoms when they are in the early stages of Lyme disease. And they may not even remember getting a tick bite. If Lyme disease goes untreated, you can have more serious symptoms over time. These include:
  • Swelling and joint pain (like arthritis).
  • Tingling and numbness in your hands, feet, and back.
  • A lack of energy that does not get better.
  • Trouble focusing your thoughts.
  • Poor memory.
  • Weakness or paralysis in your face muscles.
Causes and Risk factors: Lyme disease is spread when you are bitten by a tick that is infected with B. burgdorferi bacteria. When an infected tick bites you, bacteria travel to the tick's salivary glands and then into your body through your skin. It takes about 24 hours for a tick to attach itself to the skin and begin to feed. The tick generally must be attached to you for about 36 hours in order for it to transmit the Lyme disease bacteria. In the United States, the two types of ticks that carry Lyme disease bacteria are:
  • Deer ticks: Spread Lyme disease in the northeastern and upper Midwestern U.S.
  • Western black-legged ticks: Spread Lyme disease along the Pacific coast-mostly northern California and Oregon.
Dogs, cats, and horses can become infected with Lyme disease bacteria, but they cannot pass the illness to humans. But infected ticks may fall off the animals and then bite and infect humans. Animals may develop symptoms similar to those seen in people, including fever and swollen joints. A vaccine for dogs is available in some states. There is no convincing evidence that Lyme disease can be spread to humans by insects such as mosquitoes, flies, or fleas. Lyme disease is not contagious and cannot be spread from person to person. But certain precautions should be taken to prevent spread of the illness through ways such as blood transfusions.
  • People with active Lyme disease should not donate blood, because the bacteria that cause the illness can be transmitted this way. People who were previously treated for Lyme disease may be able to donate blood, but they should check with the blood bank first.
  • A pregnant woman may be able to pass Lyme disease to her unborn child, but proven cases are rare. Lyme disease has not been shown to cause birth defects or fetal death.
  • There is no evidence that breast-feeding mothers can pass the illness to their babies through breast milk. But a nursing mother who is suspected of having Lyme disease may be asked to stop nursing until she has completed a course of antibiotic therapy. The baby is also watched closely for symptoms of Lyme disease.
General Risk Factors: Anyone exposed to ticks is at risk for Lyme disease and other tick-borne diseases. Pets are also at risk. Naturally, anyone who is regularly outside in areas where tick rates are high has a greater than average risk for becoming infected. Age: The highest reported incidence of Lyme disease occurs among children 5 - 14 years old and adults 45 - 54 years old. Sex: Men and women are equally at risk. In general, the risk for developing Lyme disease after a tick bite is only 1 - 3%. The risk varies depending on different factors:
  • The longer the tick has fed, the greater the risk.
  • Nymph ticks carry a greater risk than adult ticks, probably because they are often too small to be detected (about the size of a pinhead). In addition, only nymph ticks that are at least partially swollen when removed pose any significant risk. (This suggests that they have feeding for a prolonged period.)
High-Risk Landscapes: Deer 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. Diagnosis: Proper diagnosis of Lyme disease is important. A diagnosis of Lyme disease is straightforward if the patient meets the following criteria: Lives in an area of tick-infestation Has the tell-tale bulls-eye rash has other symptoms (headache, joint aches, malaise, flu-like symptoms) If the patient meets all the criteria, except the rash, the doctor may undertake the enzyme-linked immunosorbent assay (ELISA) or the Western Blot test. Culture: In a few cases, if the patient seeks a diagnosis within the first 2 - 3 weeks, the doctor may take a sample of the skin or of the blood. If Lyme spirochete is present, it may be identified in the laboratory in a culture medium (a substance in which the organism can thrive and reproduce). This is necessary only if a doctor suspects Lyme but the diagnosis is not clear. The U.S. Centers for Disease Control (CDC) recommends a two-step process for Lyme disease blood tests:
  • ELISA and Other Initial Tests: The first tests used are either enzyme-linked immunosorbent assay (ELISA) or an indirect fluorescent antibody (IFA) test. ELISA is the immune test used most often for Lyme disease. (The IFA test is less accurate but may be used when ELISA isn't available.) ELISA measures antibodies that are directed against the B. burgdorferi spirochete. A newer variant is a rapid test (PreVue) that can provide results within an hour. Positive results from any of these tests still require confirmation with a Western blot test. Negative results do not require further testing.
  • Western Blot: If any of these tests is positive or uncertain, they are followed by the Western immunoblot (WB). This test is more accurate and is very helpful in confirming the diagnosis. The Western blot creates a visual graph showing bands of different colors or shading that laboratories use to interpret the immune response.
Laboratory Findings:
  • Specimens: Skin biopsy, slit smear, intradermal aspirates, Blood, and CSF are collected for examination
  • Direct examinations: Dark field microscopy and Giemsa staining are done to demonstrate the organisms.
  • Polymerase chain reaction (PCR): Blood, Plasma, Buffy coat, CSF, urine and Ticks are collected. From these specimens DNA is extracted and using Borrelia specific primers, the DNA is amplified and detected.
  • Culture: Specimens are inoculated into BSK medium, and the growth of the organisms are looked for.
  • Serology: Indirect immunofluorescence test and ELISA tests are done. Four fold rise in titre of specific 1gM antibodies are demonstrated.
  • Western blot test is done to confirm the diagnosis.
Polymerase Chain Reaction (PCR) Test: The polymerase chain reaction (PCR) test detects the DNA of the bacteria that causes Lyme disease. However, it requires technical expertise and expensive equipment, and can be performed only in a few laboratories in the country. The test also has a high risk of false-positive results. Research indicates that blood or urine samples do not provide accurate results, but skin biopsies may be useful in some cases. At this point, the PCR test is reserved for certain patients with specific diagnostic problems. For most patients, standard antibody tests are preferred. Tests for Neurologic Involvement: Analysis of Spinal Fluid. In patients who have neurologic symptoms, a lumbar puncture (a spinal tap) may be used to test for the bacteria in spinal fluid and may be useful for an early diagnosis of Lyme disease. Treatment: Treating Early Stage Lyme Disease: The early stages of Lyme disease usually involve classic bull's-eye rash (erythema migrans) and flu-like symptoms of chills and fever, fatigue, muscle pain, and headache. In rare cases, patients develop an abnormal heartbeat (Lyme carditis). All of these conditions are treated with 10 - 28 days of antibiotics. The exact number of days depends on the drug used, and the patient'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) and so is the standard antibiotic for any patient over 8 years old (except pregnant women). Doxycycline cannot be used routinely in children under 8 years old. It is a form of tetracycline and as such discolors teeth and inhibits bone growth. It can also cause birth defects, so it should not be used during pregnancy.
  • Either amoxicillin (one of the penicillins) or cefuroxime (Ceftin) -- a drug known as a cephalosporin -- are the alternative treatments for young children and some adults. Amoxicillin is the first choice and also probably the best antibiotic for pregnant women. Unfortunately, many people are allergic to penicillin. In addition, strains of bacteria are emerging that are resistant to penicillins.
  • Intravenous ceftriaxone -- another cephalosporin -- 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, are not recommended for first-line therapy.
Side Effects of Antibiotics: The most common side effects of nearly all antibiotics are gastrointestinal problems, including cramps, nausea, vomiting, and diarrhea. Allergic reactions can also occur with all antibiotics, but are most common with medications derived from penicillin or sulfa. These reactions can range from mild skin rashes to rare but severe, even life-threatening, anaphylactic shock. Some drugs, including certain over-the-counter medications, interact with antibiotics. Patients should report to their doctors all medications they 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 patients go on to develop late-stage Lyme disease, which includes Lyme arthritis and neurologic Lyme disease. Slightly more than half of patients infected with B. burgdorferi develop Lyme arthritis. About 10 - 20 % of patients develop neurologic Lyme disease. A very small percentage of patients may develop acrodermatitis chronica atrophicans, a serious type of skin inflammation. These conditions are treated for up to 28 days with antibiotic therapy. If arthritis symptoms persist for several months, a second 2 - 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, patients with arthritis may need intravenous antibiotics.) A 2 - 4 week course of intravenous ceftriaxone is used for treating severe cases of neurological Lyme disease. For milder cases, 2 - 4 weeks of oral doxycycline is an effective option. Treating Post-Lyme Disease Syndrome: In about 5% of cases, symptoms persist after treatment, a condition referred to as post-Lyme disease syndrome. The treatment of post-Lyme disease syndrome is a controversial issue. Most doctors 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 called Clostridium difficile, and can also cause the patient to become allergic to the antibiotic. Experimental and alternative remedies are also not recommended. However, some patients 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 (magnesium L-lactate dihydrate) to help relieve symptoms. No evidence suggests that they are beneficial. Any such therapies should be discussed with a doctor. Medicine and medications: Antibiotics, such as doxycycline or amoxicillin, are the main treatment for Lyme disease. The goals of treatment are to eliminate the infection and prevent complications of Lyme disease, such as problems involving the skin, joints, nervous system, or heart. The type of antibiotic prescribed, the amount, and whether the medicine is taken orally, as an injection, or through a vein (intravenous or IV) depends on how bad your symptoms are and how long you've had Lyme disease. Oral antibiotics are prescribed for early Lyme disease. Either oral or intravenous antibiotics may be used to treat late Lyme disease symptoms. Intravenous (IV) antibiotics are the treatment of choice if your nervous system is affected by late Lyme disease and you have bad headaches, neck pain, weakness or numbness in the arms or legs, or problems with thinking or memory. IV antibiotics are also used if the Lyme disease bacteria or antibodies against the bacteria have been found in your spinal fluid. Oral antibiotics are usually prescribed first for chronic Lyme arthritis (recurring swelling and joint pain), but IV antibiotics may be tried if the oral antibiotics do not work. Medication Choices: Antibiotics, such as doxycycline, amoxicillin, cefotaxime, or penicillin, are used to treat Lyme disease. Taking doxycycline for 10 days may effectively treat early Lyme disease.6 Also, if doxycycline is given within 72 hours after you are bitten by an infected tick, it may prevent Lyme disease. The type of antibiotic your doctor gives you and the number of days you take it depends on your symptoms and the stage of the disease. Talk to your doctor if you have any questions about your antibiotic treatment. There used to be a vaccine for prevention of Lyme disease in high-risk areas, but it is no longer available because of uncertainty over its effectiveness and lack of demand. DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.  

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