Lyme disease is a progressive illness that is caused by a microorganism and transmitted by the bite of an infected tick, most commonly the deer tick ( Ixodes scapularis ). It is the second fastest growing infectious disease in the United States and is endemic throughout the Northeast, the Great Lakes, and the Pacific Northwest.

Lyme disease can cause painful, debilitating tendonitis, joint pain in the feet and ankles, and plantar fasciitis. As the disease progresses, it can affect the muscles, heart, and nervous system and can cause death. The disease is treated with antibiotics.

Cause
The ticks that cause Lyme disease are very small and hard to see. They live in wooded areas, low-growing grasslands, seashores, and yards. The adult ticks are black or reddish. They feed on the blood of animals and burrow underneath the skin.

Gardening, hiking, picnicking, hunting, and other outdoor activities bring people into tick habitats, increasing the risk for infection. Ticks can be brought into contact with people when they attach themselves to pets.

Signs and Symptoms
Sometimes, a rash develops several days after infection. The rash can last from a few hours to several weeks; it can be small or as large as 12 inches across. The classic symptom is a bull's-eye rash (a round ring with a clear center), but other rashes have been noted, some of which resemble hives, eczema, sunburn, poison ivy, and flea bites. Dark-skinned persons may develop a rash that resembles a bruise. The rash may itch and feel hot, or it may have no sensation at all. It can disappear and return several weeks later. A single bite can cause multiple rashes.

Several days or weeks after a bite from an infected tick, the patient typically experiences flu-like symptoms, including aches and pains in the muscles and joints, low-grade fever, and fatigue.

Untreated, Lyme disease attacks various parts of the body as the disease progresses. Each patient may be afflicted differently. Symptoms of advanced Lyme disease include the following:

• Pain in the jaw, difficulty chewing
• Frequent or painful urination, recurring urinary tract infections
• Respiratory infections, cough, asthma, pneumonia
• Earache, hearing loss, ringing in the ears (tinitis), sensitivity to noise
• Painful inflammation of the eyes, sensitivity to light, drooping of the eyelid, conjunctivitis (pinkeye), blurred or double vision
• Sore throat, swollen glands, hoarseness, difficulty swallowing
• Headaches; facial paralysis; seizures; meningitis; stiff neck; burning, tingling, or prickling sensations; loss of reflexes and coordination
• Abdominal cramps, diarrhea, nausea, vomiting
• Cardiovascular problems, weakness, dizziness, inflammation of the heart muscle or membrane, irregular heartbeat, palpitations, fainting, shortness of breath, chest pain
• Painful swelling of the joints, arthritis, muscle inflammation and pain
• Liver infection, elevated liver enzymes, enlargement of the spleen, swollen testicles, menstrual problems
• Mood swings, irritability, poor concentration, loss of appetite, mental deterioration, depression, disorientation, sleep disturbance
• Miscarriage, premature birth, birth defects, stillbirth

Diagnosis

Lyme disease must be diagnosed clinically. Blood, urine, and spinal fluid tests produce too many false results and medications can interfere with the tests. Patients who experience a suspected Lyme disease-related rash should photograph it and bring the photo to their physician.

Ticks can be tested for infection. If a tick is found, it should be removed carefully with fine tweezers, grabbing the tick as close to the skin as possible. Do not squeeze the insect's body, apply petroleum jelly, use a burnt match, or clean the bite with alcohol while the tick is attached. These actions can transmit the bacteria. The tick should be placed in a clean container with a moistened cotton swab. A sealable storage bag may be used as a temporary container.

Differential Diagnosis
Diagnosis of Lyme disease is difficult because its symptoms often mimic those of other diseases. It is often misdiagnosed as multiple sclerosis, lupus, Lou Gehrig's disease, fibromyalgia, chronic fatigue syndrome, and Alzheimer's disease. The average Lyme disease patient sees five doctors before getting a correct diagnosis.