While most tick bites are harmless, several species can transmit 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 a newly identified ailment called 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 U.S., with LD cases more than doubling during the surveillance period of 1992 to 2006. In 2010, there were almost 23,000 confirmed cases and nearly 7,000 probable cases of LD.
- Ixodes scapularis (northeastern and north-central U.S., black-legged deer tick)
- Ixodes pacificus (Pacific coastal U.S., Western black-legged tick)
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.
Lyme disease is a year-round problem, although, April through October is considered tick season, with ticks being very active in the spring and early summer. 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.
For about 70 to 80 percent of people, the primary and first symptom is a red rash that:
- Can appear three to 30 days after infection, or not at all.
- Can last up to several weeks.
- Can be very small or very large (up to 12 inches across) and resemble a "bulls-eye."
- Can mimic such skin problems as hives, eczema, sunburn, poison ivy, flea bites.
- Can itch or feel hot, or may not be felt at all.
- Can disappear and return several weeks later.
Several days or weeks after a bite from an infected tick, a patient usually experiences flu-like symptoms such as the following:
- Stiff neck
- Aches and pains in muscles and joints
- Low-grade fever and chills
- Poor appetite
- Swollen glands
After several months, arthritis-like symptoms may develop, including painful and swollen joints.
Other possible symptoms may include the following:
- Neurological symptoms
- Heart problems
- Skin disorders
- Eye problems
- Severe fatigue
- Limb weakness
- Poor motor coordination
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 20 to 30 percent of cases.
Diagnosis for Lyme disease is a clinical one and must be made by a doctor 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:
- Your age, overall health, and medical history
- Extent of the symptoms
- Your tolerance for specific medications, procedures, or therapies
- Expectations for the course of the condition
- Your opinion or preference
Lyme disease is usually treated with antibiotics. If diagnosed at an early stage, treatment is usually given for three weeks.
Treatment will also be considered based on these and other factors:
- If you are bitten by a tick that tests positive for spirochetes.
- If you are bitten by a tick and have any of the symptoms.
- If you are bitten by a tick and are pregnant.
- If you are bitten by a tick and live in an endemic, high-risk area.
Relapse and incomplete treatment responses occur. Complications of untreated early-stage disease include: joint disease, neurologic disease, carditis, and hospitalization, some with chronic debilitating conditions.
Humans do not develop immunity to LD and reinfection is possible. In 1998, the U.S. 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:
- Dress appropriately by wearing:
- Light-colored clothing
- Long-sleeved shirts
- Socks and closed-toe shoes
- Long pants with legs tucked into socks
- Frequently check for ticks on:
- All parts of the body that bend: behind the knees, between fingers and toes, and underarms.
- Other areas where ticks are commonly found: belly button, in and behind the ears, neck, hairline, and top of the head.
- Areas of pressure points, including:
- Where underwear elastic touches the skin
- Where bands from pants or skirts touch the skin
- Anywhere else where clothing presses on the skin
- Visually check all other areas of the body, and run fingers gently over skin.
- Shower after all outdoor activities are over for the day.
- When a tick is found, remove it carefully and do not squeeze the body. Remember that any method of removal could cause transmission of the bacteria.
- Ticks can be tested for spirochetes, so place the removed tick in a glass, plastic vial, or plastic storage bag with a moistened cotton swab.
- Consider using repellents:
- Products that contain DEET are tick repellents, but do not kill the tick and are not 100 percent effective in discouraging a tick from feeding on you.
- Products that contain permethrin are known to kill ticks; however, they should not be sprayed on the skin but on clothing.
- Check pets and children for ticks.
Click here to view the
Online Resources of Travel Medicine