Description
Lyme disease is an infection caused by a bacteria normally found in deer and transmitted to humans by deer ticks. The deer tick is found in grassy areas, so people who work, play and hike in these areas are at particular risk. It is not known how long the tick needs to be in contact with the skin in order to transmit the disease.
Lyme disease was first described in 1975, and it has been identified in almost all the states. The vast majority of cases happen in people who live in or have recently traveled to the Northeastern and upper Midwest regions of the country. People of any age can get it. Late spring and summer are peak seasons.
Symptoms
Symptoms are complex and sometimes confusing. The infection begins at the site of the tick bite. There may be a red spot that looks like a target shape. A rash develops at the site of the bite and spreads to other parts of the body (Erythema Migrans). Most people do not remember a tick bite or finding a tick on their body. In initial stages, Lyme disease causes flu-like symptoms of fever, malaise, rash, neck stiffness and joint pain. These symptoms may take days or weeks to show up. Other symptoms include the chills. Joints may become tender with minimal swelling and no redness. The knee is the joint most often affected. In later stages, the disease affects the heart, neurologic system and causes Lyme arthritis.
Diagnosis
See your doctor to diagnose Lyme disease. He or she may use imaging studies to help make the diagnosis:
- In acute stages, X-rays of affected joints may show soft tissue swelling.
- In the chronic stage, signs of swelling, joint fluid and arthritis may be seen.
Diagnosing Lyme disease by blood analysis can be difficult. The signs of inflammation such as the white blood count, sedimentation rate, and C-reactive protein will be elevated, but are not specific for Lyme disease. Specific tests such as serologies may take up to four weeks to six weeks to become elevated. An elevated serum titer indicates the body's response to exposure to the bacteria, which may have been cleared, and does not necessarily reflect an active infection.
If joint swelling is present, a culture of the fluid may indicate the presence of an active infection, but is only positive about 60 percent to 70 percent of the time. A more sensitive test called PCR is being developed to detect the presence of the bacteria.
Lyme disease is usually suspected in an individual with a history of exposure, tick bite and joint pain. In cases where the presentation is unclear, the doctor will need to rule out other potential causes for the symptoms. These can include soft tissue infections, septic arthritis and rhuematoloic diseases such as juvenile arthritis.
Treatment
Most cases of Lyme disease respond to a one-month course of antibiotics. The appropriate antibiotic depends on the patient's age, allergies and special medical conditions (such as pregnancy). The prognosis is excellent if the infection is recognized early. Even with treatment, a small number of individuals can go on to develop chronic arthritis.
The prophylactic treatment for an individual presenting after finding a tick on their body is controversial. Talk with your doctor. A vaccine has been developed, but it is currently not recommended because of potential side effects.
Risk Factors/Prevention
Tell your doctor if you travel to areas of high risk for Lyme disease, especially during summer months. Taking precautions is very important to avoid getting this potentially dangerous condition. While hiking, stay on hiking trails and avoid deep grassy areas. Wear pants, long sleeve shirts and high socks. Check for ticks on household pets and anyone who may have come in contact with high-risk areas. If a tick bite is suspected, contact your family physician immediately.
March 2005
Reviewed by members of POSNA (Pediatric Orthopaedic Society of North America)
Information provided by American Association of Orthopaedic Surgeons
