5 FACTS ABOUT LYMES
Lyme disease is the most common vector-borne disease (transmitted to people via animal or insect) in the United States, with about 300,000 cases reported every year. Thats a significant number, particularly considering that over 95% of these cases occur in only 12 states (mostly along the east coast, from Maine to Maryland, and a few states in the Midwest: Minnisota, Michigan, and Northwest: northern California and Oregon). "Lyme" is actually the name of a town in Conniticuit where the disease was first identified. Lyme disease occurs in a bimodal age distribution in humans: 5-9 years old, and 50-59 years old.
Lyme disease is caused by a bacteria Borrelia burgdorferi. The bacteria lives in the gut of the tick, and becomes activated when the tick attaches to humans, the bacteria enters the saliva of the tick and then enters a person's blood stream. This process doesnt happen immediately, an infected tick must be attached to a human for over 24 hours, and this means that being bitten by a tick does not mean you are infected as well. It requires a prolonged exposure to be at risk for the disease.
Diagnosis. Lyme occurs in 4 stages.
Stage-1 Early Local. Lyme disease is suspected in kids living in areas endemic to ticks that present to a doctor with the classic "bulls-eye rash" or symptoms that include fever, fatigue, muscle aches (these are all pretty generalized flu-like symptoms, making diagnosis tough). Symptoms present around 3-30 days after transmission. Interestingly, 20% of kids dont report symptoms, and 80% dont recall a tick bite.
Stage-2 Early Disseminating and Stage-3 Late Disseminating. This occurs weeks to months after the initial infection. This is when a spontaneous knee effusion will occur, or migrating arthralgia (joint pain). Any joint can be infected although the knee is the most common.
Kids suspected of having Lyme disease because of a knee effusion should have labs drawn (ESR,CRP) and possibly knee synovial fluid aspirated (depending on the lab values) to differentiate between septic arthritis and lyme arthritis. Blood or synovial fluid can be sent for Enzyme Immunoassay (ELISA). However this test lacks the specificity to act as a stand-alone test. Therefore, diagnosis is based on a two-tier system, so if ELISA+ve, the fluid is sent for IgM and IgG Western Blot. If these findings are also positive, then patient should be treated for Lyme. Synovial fluid PCR is not sensitive enough for routine use.
Stage-4: Posttreatment Syndrome. Roughly 10% of patients will continue to experience symptoms similar to Lyme disease despite multiple treatments. This is considered to a result of an autoimmune reaction after Lyme disease has been treated (bacteria is probably gone), although its full etiology is not completely understood.
Treatment. Lyme disease is treated with antibiotics (because the infection is caused by a bacteria). Patients typically receive 28 days of one of the following antibiotics: Doxycycline 100 mg BID, Amoxicillin 500 mg BID, Cefuroxime 500 mg BID.
The knee effusion does not respond immediately to treatment, but does resolve after a few weeks. However, if there is persistent effusions after a few months, a secondary treatment is recommended consisting of 2 - 4 weeks of IV antibiotics (ceftriaxone).
NSAIDS can be given throughout treatments to improve symptoms of pain and swelling.
There are some studies that suggest prophylactic treatment for lyme disease (a single dose of doxycycline in kids over 8 years old) if a tick bite was observed, however, there must be evidence to suggest the tick has been attached for at least 36 hours, and the dose of antibiotics must be given within 72 hours of the initial contact, and the tick bite must occur in an area of high incidence of Lyme disease. These strict criteria are in place because the overall transmission rate of lyme after tick bites is extremely low.
Outcome. 99% of patients treated for early lymes disease, and 90% of patients treated for early disseminated (knee effusion) lymes respond completely to antibiotic therapy.
If left untreated, however, Lyme can progress systemically to involve cardiac, neurologic, and musculoskeletal sequale. Knee effusions have about 60% chance of eventually developing lyme arthritis (cartilage degeneration secondary to the lasting inflammation of lymes infection).
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