by Nathan Wei, MD, FACP, FACR
Nathan Wei is a nationally known board-certified rheumatologist and author of the Second Opinion Arthritis Treatment Kit. It's available exclusively at this website... not available in stores.
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Information from the Arthritis Foundation, the American College of Rheumatology and the CDC
Lyme arthritis is one of the common complications of Lyme disease.
Lyme disease is the most common tick transmitted disease in the United States. It is caused by the spirochete, Borrelia burgdorferi, and it is transmitted to humans by tick bites. Lyme disease cannot be transmitted from an infected person to another person. The infection can involve multiple organ systems and has multiple signs and symptoms.
Lyme disease is transmitted to people by ticks of the Ixodes ricinus complex. These include I. scapularis in the eastern United States, I. pacificus in the western United States, I. ricinus in Europe, and I. persulcatus in Asia.
There have also been case reports of Lyme disease after bites of biting flies.
Ixodes scapularis has a two year life cycle in three stages. Sub-adult forms (larvae, nymphs) feed on a wide variety of small mammals, birds, and reptiles, but prefer to feed on white-footed mice, which are the important reservoir of infection. Adults prefer to feed and mate on white-tailed deer.
Cases of Lyme disease have been reported from almost every state in the U.S. Since 1989, approximately 75% of cases have been reported from just four states - New York, Connecticut, New Jersey, and Pennsylvania.
The highest attack rates are in children up to 14 years of age and in persons over the age of 30 years.
Most cases of Lyme disease are thought to result from exposure to infected ticks. Persons who reside, work, or recreate in wooded areas or areas of overgrown brush are at risk of acquiring the infection. A useful clue to the possible presence of ticks is whether deer have been commonly seen in the area.
One study of outdoor workers in New Jersey identified occupational tick exposure, hunting, and male gender to be risk factors and antibiotic use and insect repellent use to be protective factors for anti-B. burgdorferi antibody seropositivity.
Several epidemiologic studies have documented that outdoor workers have an increased risk of Lyme disease.
The classic presentation of early Lyme disease is the appearance of a characteristic rash, erythema chronicum migrans. This rash begins as a small red spot at the site of a tick bite, generally 3-30 days after a tick bite, but most patients do not recall a tick bite at the site. Over several days to weeks, it can grow in size, with red borders and often a clearing center.Concentric rings of redness may appear, resembling a target. The rash can grow to more than 20 cm in diameter, and the specificity of this sign for the diagnosis of Lyme disease is probably improved with increasing diameter of the rash (a minimum diameter of 5 cm is suggested by the Centers for Disease Control for diagnosis). B. burgdorferi can be detected (by culture or polymerase chain reaction) at the leading edge of the rash.
While the vast majority of patients develop a rash, the classic, target-shaped rash is not the most common appearance of this rash. Central clearing probably occurs in less than 40% of cases, and solid red rashes are probably most common.
Within weeks to months of becoming infected, stage 2 or early disseminated disease occurs. Approximately 4-10% of patients in the U.S. develop heart involvement, including conduction defects (e.g., atrioventricular block, complete heart block, bundle branch block, fascicular block), tachyarrhythmias (e.g., atrial due to pericarditis,and myopericarditis.
Involvement of the central or peripheral nervous systems may occur in up to 10 to 20% of cases. Patients have headache, fatigue, stiff neck, and malaise, and may have meningitis, neuroborreliosis, cranial neuropathies (especially facial nerve palsy, which can be bilateral), peripheral neuropathy, radiculitis, myelopathy, or brachial plexopathy. Lyme disease may also involve the eye.
Musculoskeletal manifestations of Lyme disease are very common. During early infection, migratory joint pains and pain in bursae, tendon, muscle, or bone occur in the majority of patients. Weeks to months later, arthritis involving large joints (most commonly knees, but also shoulders, ankles, elbows, and other sites), may develop. Lyme arthritis is one manifestation of persistent or late Lyme disease.
In the United States, approximately 60% of untreated patients will develop intermittent episodes of joint pain and swelling, months to years after the infecting tick bite. The most common presentation is a single involved knee, but both large and small joints may be affected, and usually only one or two joints at a time. Over time, the frequency and severity of attacks tends to decline, and, on average, the proportion of patients with recurrent attacks drops by 10-20% annually. Approximately 10% of untreated patients may develop chronic arthritis, defined as one year or more of continuous joint inflammation. Some patients with Lyme arthritis have no resolution of symptoms even after long-term antibiotic therapy, and have antibiotic treatment-resistant Lyme arthritis. It is thought that this condition is an autoimmune phenomenon.
The history is very important to the diagnosis of the disease. A detailed description of the rash may be helpful if it is not present at the time of the examination. The history that the rash expanded over several days, eventually getting larger than 5 cm in diameter, is a useful clue.
Classical later presentations such as unilateral facial palsy, heart block, or arthritis of the knee, should prompt diagnostic tests for Lyme disease. Diagnosis of Lyme disease is aided by serologic testing, which should include antibody testing by ELISA, and if positive, follow-up with Western blot testing for both immunoglobulin G and M antibodies. By 6-8 weeks of infection, most patients will have an antibody response. The sensitivity of serologic testing is approximately 50% at the erythema migrans stage, but increases to more than 90% by the later stages of the disease. Serologic testing is therefore not very helpful in a patient with classic erythema migrans, who will be treated for Lyme disease regardless of the serologic test result. The specificity of serologic testing is approximately 90-95% for all stages of the disease.
As recommended by the Centers for Disease Control, a positive ELISA test result must be followed by Western blot testing. The usual criterion for a positive Western blot for IgM is at least two bands corresponding to proteins of specific molecular weights (two of the following three: 23, 39, or 41 kDa). For Western blot testing for IgG, the usual criterion is five bands corresponding to proteins of specific molecular weights (five of the following ten: 18, 23, 28, 30, 39, 41, 45, 58, 66, or 93 kDa). A positive IgM test alone in patients who have had symptoms for longer than one month is insufficient evidence of infection and is more likely to be a false positive, rather than a true positive, result. This is likely due to the less stringent criterion for a positive IgM Western blot (only two positive bands). Even though both IgG and IgM antibodies are tested by the Western blots, these results do not distinguish between active and past infections. Test results can remain positive for years.
Lyme disease serologic testing should be used with caution in patients complaining solely of nonspecific symptoms such as, for example, chronic fatigue, headaches, or diffuse musculoskeletal pain. False positive results can present a diagnostic conundrum.
Lyme disease is considered treatable at all stages, with either oral or intravenous antibiotics. There have been few randomized clinical trials of treatment, so optimal choice of antibiotic or optimal duration of treatment are not known. In general, early Lyme disease in adults is treated with doxycycline 100 mg orally twice daily or amoxicillin 500 mg orally three times daily for 20 to 30 days. Doxycycline should not be used in children under age nine years or pregnant women. Other antibiotic choices include phenoxymethyl penicillin, tetracycline, cefuroxime axetil, erythromycin, or azithromycin, with the latter two considered to be second line choices.
Doxycycline for 30 day courses has been used to treat certain heart, nervous system, and joint manifestations of Lyme disease. More severe manifestations of Lyme disease are generally treated with intravenous antibiotics, most often ceftriaxone 2 gm twice daily for 14 to 30 days, and these include Lyme meningitis, neuroborreliosis, arthritis not responsive to doxycycline, and severe cardiac manifestations.
Patients should make slow, steady progress. Patients who have lingering symptoms after treatment should not be routinely retreated with antibiotics without clear evidence of antibiotic failure. Non-steroidal anti-inflammatory medications, anti-depressants, exercise, and physical therapy have been used for symptomatic relief after an adequate trial of antibiotic therapy.
Individuals should be educated to check themselves, very carefully, at the end of each day in tick-infested habitats, for ticks on their skin. Any ticks should be removed and discarded. Other things to consider: DEET (n,n-diethyl-m-toluamide) use on skin (an insect repellent) or permethrin use on clothing (an insecticide which kills ticks), tucking pants into socks, wearing long sleeves and long pants, and wearing light-colored clothing for easier spotting of ticks, can also be used. Environmental interventions such as elimination of leaf litter, fencing, deer elimination, and insecticide applications have been shown to decrease tick burden in residential areas.
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