The laboratory diagnosis of Lyme borreliosis

Abstract

Summary Borrelia burgdorferi, the causative organism of Lyme disease, is transmitted to man primarily by the bite of Ixodid ticks. Lyme disease has a world-wide distribution and is currently the most frequently reported tick-borne disease in Europe and North America. The most common symptoms involve the skin, nervous system, heart and joints. Lyme disease responds well to antibiotic therapy, and early treatment can prevent progression to the later more serious clinical complications. However, clinical diagnosis is difficult in the absence of erythema migrans, the characteristic early skin rash. Infection by B. burgdorferi can be confirmed in the laboratory using both direct and indirect methods. Direct methods include cultivation of the organism, immunohistology and antigen detection. Indirect methods rely on a range of serological tests. Culture of B. burgdorferi is of limited use in routine diagnosis but is helpful in confirming atypical cases of Lyme disease. The most commonly used serological method is an enzyme-linked immunosorbent assay screen, with confirmation by immunoblot where required. Serological testing is complicated by the poor immune response in early infection and the relatively high prevalence of cross-reacting antibody in the normal population. Despite recent improvements in the specificity and sensitivity of some serological tests arising from the use of purified borrelial antigens, the diagnosis of Lyme disease remains primarily clinical.