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Lyme disease, also known as Lyme borreliosis, is an infectious disease caused by bacteria of the Borrelia type which is spread by ticks. The most common sign of infection is an expanding area of redness on the skin, known as erythema migrans, that begins at the site of a tick bite about a week after it has occurred. The rash is typically neither itchy nor painful. Approximately 25–50% of infected people do not develop a rash. Other early symptoms may include fever, headache and feeling tired. If untreated, symptoms may include loss of the ability to move one or both sides of the face, joint pains, severe headaches with neck stiffness, or heart palpitations, among others. Months to years later, repeated episodes of joint pain and swelling may occur. Occasionally, people develop shooting pains or tingling in their arms and legs. Despite appropriate treatment, about 10 to 20% of people develop joint pains, memory problems, and feel tired for at least six months.
Lyme disease is transmitted to humans by the bite of infected ticks of the genus Ixodes. Usually, the tick must be attached for 36 to 48 hours before the bacteria can spread. In North America, Borrelia burgdorferi and Borrelia mayonii are the cause. In Europe and Asia, the bacteria Borrelia afzelii and Borrelia garinii are also causes of the disease. The disease does not appear to be transmissible between people, by other animals, or through food. Diagnosis is based upon a combination of symptoms, history of tick exposure, and possibly testing for specific antibodies in the blood. Blood tests are often negative in the early stages of the disease. Testing of individual ticks is not typically useful.
Prevention includes efforts to prevent tick bites such as by wearing long pants and using DEET. Using pesticides to reduce tick numbers may also be effective. Ticks can be removed using tweezers. If the removed tick was full of blood, a single dose of doxycycline may be used to prevent development of infection, but is not generally recommended since development of infection is rare. If an infection develops, a number of antibiotics are effective, including doxycycline, amoxicillin, and cefuroxime. Standard treatment usually lasts for two or three weeks. Some people develop a fever and muscle and joint pains from treatment which may last for one or two days. In those who develop persistent symptoms, long-term antibiotic therapy has not been found to be useful.
Antibiotics are the primary treatment. The specific approach to their use is dependent on the individual affected and the stage of the disease. For most people with early localized infection, oral administration of doxycycline is widely recommended as the first choice, as it is effective against not only Borrelia bacteria but also a variety of other illnesses carried by ticks. Doxycycline is contraindicated in children younger than eight years of age and women who are pregnant or breastfeeding; alternatives to doxycycline are amoxicillin, cefuroxime axetil, and azithromycin. Individuals with early disseminated or late infection may have symptomatic cardiac disease, refractory Lyme arthritis, or neurologic symptoms like meningitis or encephalitis. Intravenous administration of ceftriaxone is recommended as the first choice in these cases; cefotaxime and doxycycline are available as alternatives.
These treatment regimens last from one to four weeks. If joint swelling persists or returns, a second round of antibiotics may be considered. Outside of that, a prolonged antibiotic regimen lasting more than 28 days is not recommended as no clinical evidence shows it to be effective. IgM and IgG antibody levels may be elevated for years even after successful treatment with antibiotics. As antibody levels are not indicative of treatment success, testing for them is not recommended.