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Lyme disease: a brief overview

Posted by Tom Gocke on Aug 15, 2018 8:02:00 AM

Lyme disease is a multisystem illness with acute and chronic manifestations as a result of infection by the spirochete Borrelli burgdorferi. In the USA, the bacteria are transmitted to people and animals by the bite of an infected tick,Ixodes scapularis, (commonly called the blacklegged or deer tick), and Ixodes pacificus(western blacklegged tick) in the West. Although other types of ticks such as the Dermancentor variabilis (American dog) have been shown to carry the Lyme bacteria.

Lyme disease was first encountered in 1975 when several children in a Connecticut town developed arthritic illnesses of unknown origin. Lyme disease is one of the most prevalent vector borne illnesses in the United States with nearly 50,000 cases reported since 1982. The Northeast, Mid-Atlantic and Southeastern portions of the US report the highest incidences of Lyme disease followed by the Midwest and Pacific Northwest. Lyme disease has also been reported in Asia and parts of Europe.

Patients with Lyme disease initially have variable flu like symptoms. It is often overlooked as being viral illness when in fact it is the early manifestations of this disease. The symptoms are commonly accompanied by skin rash (erythema migrans) or a more distinctive skin lesion known as a “target/bulls eye lesion” (variant of erythema migrans) A “target lesion” is found on the extremities or in areas where the patient has been bitten by a tic. An people of color, the rash may appear more like a bruise. The rash is usually not itchy. The rash can be mistaken for a spider bite.

Arthralgia associated with Lyme disease will present as isolated unilateral knee pain and swelling. Remember that unilateral joint arthralgia and swelling should make the provider think of other possible manifestations. However polyarticular arthralgias are uncommon with Lyme disease. There are cardiovascular manifestations that occur and less than 10% of patients and neurologic symptoms that affect less than 15% of patients. These neurologic effects typically present as cranial nerve palsy (Bell's palsy). In patients who have developed chronic Lyme disease, often have symptoms that do not manifest themselves for several years but develop chronic or recurrent arthritic conditions. Patient's can present with chronic fatigue, fibromyalgia-type symptoms, encephalopathy's resulting in memory loss and difficulties with concentration.

Physical examination for patients exposed to Lyme disease should undergo a comprehensive skin assessment, evaluation for erythema migrans and joint evaluations for symptomatic complaints. Patient's who present with Lyme disease related arthralgia would have limited range of motion, joint effusions and/or symptoms of acute or subacute recurrent synovitis. There is usually no history of trauma, joint instability or musculoskeletal weakness directly related to Lyme disease. X-ray findings may reveal some osteoarthritis joint changes but no clear-cut manifestations are associated with Lyme disease. Lyme disease is usually diagnosed through serology specifically looking for levels of  Borrelia in the blood. These are typically referred to as a Lyme panel or Lyme titers. A positive Lyme titer is usually evident in later stages of the disease and is not found on acute infection. Difficulty in diagnosing Lyme disease can occur secondary to patients who have an underlying history of arthritic changes in weight bearing joints, history of cranial nerve palsy, fibromyalgia or chronic fatigue syndrome's, cognitive abnormalities, cardiac conduction abnormalities and peripheral vascular disease or peripheral neuropathy.

Avoidance is the most common way to minimize exposure to Lyme disease. Patients should take great care when walking in wooded areas or in areas that have a history of endemic Lyme disease. Long sleeves, tucking in shirttails, wearing long pants and tucking long pants into socks are all methods to limit ticks gaining access to skin surfaces. Frequent checks of clothing and skin are important to limit tick bites. If an embedded tick is found on the skin, it should be removed within 24-36 hours to minimize exposure to Lyme disease. The best method for removal of imbedded ticks is using fine tweezers to disengage the tick. Using heat or caustic chemicals can have an adverse effect on the patient's skin tissues. Once a tick is removed the skin should be thoroughly cleansed and monitored for several days. Antibiotic treatment for Lyme disease is typical but often not necessary if the tick is removed within 24 hours. However patient's concerns, expectations and sound clinical judgment should all be taken into consideration when determining if antibiotic therapy is warranted.

Clinicians should prescribe amoxicillin, cefuroxime or doxycycline as first-line agents for the treatment of EM. Azithromycin is also an acceptable agent, particularly in Europe, where trials demonstrated it either outperformed or was as effective as the other first-line agents. Initial antibiotic therapy should employ 4–6 weeks of amoxicillin 1500–2000 mg daily in divided doses, cefuroxime 500 mg twice daily or doxycycline 100 mg twice daily or a minimum of 21 days of azithromycin 250–500 mg daily. Pediatric dosing for the individual agents is as follows: amoxicillin 50 mg/kg/day in three divided doses, with a maximal daily dose of 1500 mg; cefuroxime 20–30 mg/kg/day in two divided doses, with a maximal daily dose of 1000 mg and azithromycin 10 mg/kg on day 1 then 5–10 mg/kg daily, with a maximal daily dose of 500 mg. For children 8 years and older, doxycycline is an additional option. Doxycycline is dosed at 4 mg/kg/day in two divided doses, with a maximal daily dose of 200 mg. Higher daily doses of the individual agents may be appropriate in adolescents.

Selection of the antibiotic agent and dose for an individual patient should take several factors into account. In the absence of contraindications, doxycycline is preferred when concomitant Anaplasma or Ehrlichia infections are possibilities. Other considerations include the duration and severity of symptoms, medication tolerability, patient age, pregnancy status, comorbidities, recent or current corticosteroid use.

Lyme disease can often be overlooked in patients who present with flu-like symptoms and who report little exposure to ticks ( Borrelia spirochete). It is important to determine the level of a patient’ outdoor activities and possible tick exposure during the historical review. This is especially important during warm weather months and for patients living in high exposure areas. However, providers who work in year-round warm weather climates should always be suspicious of Lyme disease exposures. If detected early and the tick is removed no treatment is necessary. However, in a patient who has concerns regarding contracting Lyme disease or who presents with the classic target lesion (erythema migrans) antibiotic therapy is recommended. In most cases patients will have resolution of there symptoms after completing antibiotic therapy and usually will not be affected long-term.

Bibliography:

Lyme Disease (Borrelia burgdorferi) 2017 Case Definition https://wwwn.cdc.gov/nndss/conditions/lyme-disease/case- definition/2017/

Cameron DJ, Johnson JB, Maloney EL: Evidence assessments and guideline      recommendations in Lyme disease: the clinical management of known tick   bites, erythema migrans rashes and persistent disease, Expert Review of Anti-Infective therapy; 2014; 12(9):1103-1135 

Topics: Lyme disease