While most tick bites are harmless, several species can cause life-threatening diseases. Two of these well-known diseases are Rocky Mountain Spotted Fever and Lyme disease. Ticks can also transmit tularemia (a plague-like disease in rodents that can be transmitted to man), relapsing fever, and ehrlichiosis (an abrupt illness consisting of fever, rash, nausea, vomiting, and weight loss).
Lyme disease (LD) is a multi-stage, multi-system bacterial infection caused by the spirochete Borrelia burgdorferi, a spiral shaped bacterium that is most commonly transmitted by a tick bite. The disease takes its name from Lyme, Connecticut, where the illness was first identified in the United States in 1975.
According to the Centers for Disease Control and Prevention (CDC), Lyme disease continues to be a rapidly emerging infectious disease, and is the leading cause of all insect-borne illness in the US. According to the CDC, LD cases more than doubled during the surveillance period of 1992 to 2006. In 2008, there were nearly 23,000 confirmed cases and nearly 7,000 probable cases of LD.
Ticks prefer to live in wooded areas, low-growing grasslands, and yards. Depending on the location, anywhere from less than 1 percent to more than 50 percent of the ticks are infected with spirochetes.
Although Lyme disease is a year-round problem, April through October is considered tick season. Cases of Lyme disease have been reported in nearly all states in the U.S. and in large areas in Europe and Asia.
The list of possible symptoms is long, and symptoms can affect every part of the body. The following are the most common symptoms of Lyme disease. However, each individual may experience symptoms differently:
The primary symptom is a red rash that:
Several days or weeks after a bite from an infected tick, a patient usually experiences flu-like symptoms such as the following:
After several months, arthritis-like symptoms may develop, including painful and swollen joints.
Other possible symptoms may include the following:
Some people may develop post-Lyme disease syndrome (PLDS), a condition also known as chronic Lyme disease, characterized by persistent musculoskeletal and peripheral nerve pain, fatigue, and memory impairment.
Lyme disease is difficult to diagnose because symptoms are not consistent and may imitate other conditions. The primary symptom is a rash, but it may not be present in up to 20 percent of cases.
Diagnosis for Lyme disease is a clinical one and must be made by a physician experienced in recognizing LD. Diagnosis is usually based on symptoms and a history of a tick bite. Testing is generally done to eliminate other conditions and may be supported through blood and laboratory tests, although these tests are not absolutely reliable for diagnosing LD.
Research is underway to develop and improve methods for diagnosing LD.
The symptoms of Lyme disease may resemble other medical conditions or problems. Always consult your doctor for a diagnosis.
Specific treatment for Lyme disease will be determined by your doctor based on:
Lyme disease in the earliest stage is usually treated with antibiotics for three weeks.
Treatment will also be considered based on these and other factors:
Relapse and incomplete treatment responses occur. Complications of untreated early-stage disease include: joint disease, neurologic disease, carditis, and frequent hospitalizations to manage the disease. Some of these complications result in chronic, debilitating conditions.
Humans do not develop immunity to LD and reinfection is possible. In 1998, the US Food and Drug Administration (FDA) had approved a new vaccine against Lyme disease called LYMErix. The vaccine was not 100 percent effective, however, and the FDA still recommended using other preventive measures. In 2002, the manufacturer of LYMErix announced that the vaccine would no longer be available commercially.
Some general guidelines for preventing LD include the following:
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