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Lyme disease is an infectious disease that is caused by a few species of group of spiral-shaped bacteria called Borrelia. In the United States, the species of Borrelia that usually causes Lyme disease is called Borrelia burgdorferi. In Europe and Asia, the species Borrelia afzelii and Borrelia garinii also cause Lyme disease. Regardless of which species causes the disease, the bacteria enter humans by way of a bite from a type of tick called ixodid. These ticks receive the bacteria from small mammals, such as mice, chipmunks, and birds. Deer also are vital to the tick life cycle.
Lyme disease is on the rise in developed countries, possibly because an increasing number of people are spending leisure time outside. Since the early 1990s, the annual number of cases reported in the United States has increased from 10,000 to 30,000, but the disease is thought to occur in ten times the reported number of people, meaning 100,000 to 300,000 people each year in the US alone. It is called Lyme disease because it was first identified in Lyme, Connecticut, back in the 1970s. Most of the US cases occur in New England and in states of the mid-Atlantic region. Some cases occur in Wisconsin and Minnesota, and more rarely in Oregon and northern California. Children are infected the most, but middle-aged adults are now catching Lyme disease frequently, likely because they are spending more time outdoors. Having young children who play outside and walking or jogging outside during pregnancy puts you at risk for Lyme disease, if you live where Lyme disease is common. The presence of ticks that carry the Borrelia bacteria is more likely from the spring through autumn and in certain geographical regions, as mentioned above.
Lyme disease develops in stages. During the first stage, there is a rash around the tick attachment site, often with flu-like symptoms. Then, the condition can evolve to a more serious, second stage, involving multiple organs and the nervous system, lasting for weeks to months and throughout the course of pregnancy, even if the tick bite occurred before you got pregnant. Patients also can suffer a third stage, characterized by arthritis and sometimes problems in muscle, nerve, and skin. These symptoms are not due to a persistent bacterial infection, but probably from damage caused by the infection during the early stages. For all these reasons, it is very important to recognize Lyme disease early on.
Lyme disease is diagnosed by your history of possible exposure to ticks in a region where ticks carry Borellia bacteria, based on findings on your physical examination, and based on laboratory tests. Physical examination findings that suggest Lyme disease include a rash called erythema migrans, that begins 3-32 days after the bite, and the finding of an actual tick in the center of the rash. Classically, the rash has the look of a target with a bull’s eye, but there is a great deal of variation, not only because skin color varies among people, but also because the amount of reaction in the skin varies. Flu-like symptoms, such as headache and muscle/joint pain can be part of Lyme disease stage 1, but erythemia migrans is the frequent sign to identify the presence of Lyme disease. That’s because you can get bitten by a tick and not get infected with the bacteria.
Laboratory testing that can confirm the diagnosis consists of what doctors call “serology”. In the case of Lyme disease, serology includes one test called ELISA and another called a Western blot. ELISA is performed first. If ELISA comes out as positive or a ‘maybe’, doctors will order a Western blot test, which can confirm the diagnosis of Lyme disease. Western blot also can reveal how many weeks or months you have had the infection.
If you are outside and notice a tick on you and can remove it, this is enough to prevent the infection. If you return home after an outdoor activity and find a tick on your body –generally on the feet, ankles, or leg, or on the groin, back, waist, or armpit– removing the tick can prevent infection, so long as the tick has not been there for a long time. Since stage 1 can take up to 32 days to begin, if you remove the tick, you should make an appointment to see your physician. If you don’t have any symptoms, the doctor will want to observe you to see whether erythema migrans appears.
Erythema migrans can last up to 3-4 weeks before resolving, but if not recognized and treated with antibiotic medication, weeks to months later you can develop stage 2, which can show up with problems in the heart and problems with the nerves that control functions in the head and neck. You also could develop meningitis, which is an inflammation of the connective tissue layers that surround the brain. After months to years, stage 3 can begin, with arthritis as the main symptom, although there also can be muscular and nervous system effects. Its important to appreciate that these later effects of Lyme disease are not the result of the bacterial infection continuing for months to years. Instead, they are complications resulting from damage occurring earlier in the course of the disease. Consequently, there is no good rationale for antibiotic treatment to be given during the many months that these higher stage symptoms persist. As for the pregnancy and the baby, some studies have found that Lyme disease elevates the risk of spontaneous abortion (miscarriage), as well as stillbirth, premature delivery, trouble with growth, and low birth rate. However, such studies are based on just a small number of cases, and research continues.
In non-pregnant adults, the treatment of choice for Lyme disease is doxycycline. The use of this drug in pregnancy is surrounded by controversy, since it belongs to a class of drugs called tetracyclines, that generally are not to be used during pregnancy. Yet, doxycycline may be of lower risk. The drug also enters breast milk, so it should be avoided during lactation. However, antibiotics are mandatory to stop Lyme disease before it advances to stage 2 or 3. There are other antibiotic regimens that seem to be safe and an effective, including amoxicillin and cefuroxime.