Re: Zanedbaná borelióza

Serology

Following the transmission of B. burgdorferi from a tick bite, specific immunoglobulin M (IgM) antibodies appear first, usually at 3-4 wk, peak at 6-8 wk, and subsequently decline. Sometimes a prolonged elevation of IgM antibodies occurs despite effective antimicrobial treatment. (For that reason, the results of tests for specific IgM antibodies alone should not be used as a reliable indicator of either active or recent infection.) Specific IgG antibodies usually appear at 4-8 wk, peak after 4-6 mo, and can remain elevated for years, particularly in patients with arthritis. The antibody response to B. burgdorferi may be blunted in patients with early Lyme disease who are treated promptly with an effective antimicrobial agent.

By far the most common method used to detect IgG and IgM antibodies is the enzyme-linked immunosorbent assay (ELISA). This method is sensitive but not optimally specific. The ELISA sometimes produces false-positive results because of antibodies that cross-react with other spirochetal infections (e.g., syphilis, leptospirosis, or relapsing fever), or certain viral infections (e.g., Epstein-Barr virus or parvovirus B19) or that occur in certain autoimmune diseases (e.g., systemic lupus erythematosus). The positive predictive value of the ELISA result depends primarily on the plausibility that the patient has Lyme disease based on the clinical and epidemiologic history and the physical examination (the pretest probability). For patients who have been in endemic areas with opportunities for Ixodes tick exposure and who have typical clinical manifestations of Lyme disease, the pretest probability is high and positive ELISA results are usually true positives. For patients who are from nonendemic areas and/or who have little risk for Ixodes tick exposures and/or have nonspecific symptoms (low pretest probability), rates of false-positive results are high.

Western immunoblotting is well standardized, and there are accepted criteria for interpretation. Five of 10 IgG bands and 2 of 3 IgM bands is considered positive. The Western blot is not as sensitive as ELISA, especially in early infection, but it is highly specific. Any positive or equivocal ELISA should be confirmed with Western blotting. This two-tier testing is the recommended laboratory evaluation of most cases of Lyme disease and is associated with a high degree of sensitivity and specificity when used appropriately.

Clinicians should be aware that Lyme disease might not be the cause of a patient""s symptoms despite the presence of antibodies to B. burgdorferi. The test result may be falsely positive (as described for ELISA), or the patient might have been infected previously. Antibodies to B. burgdorferi that develop with infection can persist for many years despite adequate treatment and clinical cure of the disease. In addition, because some people who become infected with B. burgdorferi are asymptomatic, the background rate of seropositivity among patients who have never had clinically apparent Lyme disease may be substantial in endemic areas. Finally, because antibodies against B. burgdorferi persist after successful treatment, there is no reason to obtain follow-up serologic tests.

RECOMMENDED TREATMENT OF LYME DISEASE
DRUG PEDIATRIC DOSING
Amoxicillin 50 mg/kg/day in 3 divided doses (max 1,500 mg/day)
Doxycycline 4 mg/kg/day in 2 divided doses (max 200 mg/day) (see text regarding doxycycline use in children)
Cefuroxime axetil 30 mg/kg/day in 2 divided doses (max 1,000 mg/day)
Ceftriaxone (IV)*[†] 50-75 mg/kg/day once daily (max 2,000 mg/day)
RECOMMENDED THERAPY BASED ON CLINICAL MANIFESTATION
Erythema migrans Oral regimen, 14-21 days
Meningitis Ceftriaxone, 10-28 days
Cranial nerve palsy Oral regimen, 14-21 days (see text regarding possible need for lumbar puncture)
Cardiac disease Oral regimen or ceftriaxone, 14-21 days (see text for specifics)
Arthritis[‡] Oral regimen, 28 days
Late neurologic disease Ceftriaxone, 14-28 days

From Wormser GP, Dattwyler RJ, Shapiro ED, et al: The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America, Clin Infect Dis 43:1089–1134, 2006.