Lecture 11 serology Lyme’s Disease Dr. Dalia Galal

Introduction Lyme disease was named in 1977 when arthritis was observed in a cluster of children in and around Lyme, CN Conditions suggested that this was an infectious disease probably transmitted by an arthropod Further investigation revealed that Lyme disease is caused by the bacterium

Causative Organism Borrelia burgdorferi Loosely coiled spirochete 8-20 micrometers

Vector Ixodes ticks are much smaller than common dog and cattle ticks Below adult female, adult male, nymph, and larva on a centimeter scale. Humans acquire disease from bite of nymphal or adult tick.

Three Stages of Disease Localized rash – erythema chronicum migrans (chronic migrating redness) Dissemination to multiple organ systems Chronic disseminated stage often with arthritic symptoms

Localized Rash (chronic migrating redness)

Dissemination Signs of early disseminated infection usually occur days to weeks after the appearance of a solitary erythema migrans lesion Neurologic – Bell’s Palsy Musculoskeletal manifestations may include migratory joint and muscle pains Late disseminated Lyme disease is intermittent swelling and pain of one or a few joints.

Chronic Disseminated Chronic arthritis Chronic axonal polyneuropathy Lyme disease morbidity may be severe, chronic, and disabling. Rarely, if ever, fatal

Diagnosis Diagnosed clinically, confirmed serologically. Often appropriate to treat patients with early disease solely on the basis of objective signs and a known exposure. CDC recommends testing initially with a sensitive first test, ELISA or an immunofluorescence assay (IFA) test, followed by testing with the more specific Western immunoblot (WB) test to corroborate equivocal or positive results obtained with the first test.

Serology Patients with early disseminated or late-stage disease usually have strong serological reactivity Antibodies often persist for months or years following successfully treated or untreated infection. seroreactivity alone cannot be used as a marker of active disease

Problems with Serology IFA false positive may occur if patient has syphilis, relapsing fever or reumatoid arthritis (RA). IFA interpretation highly subjective Enzyme immunoassay (EIA) lacks sensitivity in early disease. EIA false positives with syphilis, other treponemes, and autoimmune disease.

Western Blot Must be used if the Lyme IgG/IgM antibody serology is equivocal or positive "Osp" refers to outer surface protein of the bacteria. "kDa" is the abbreviation for "kilodalton," which is used for molecular weight designations. Lyme antibodies of importance are against the following molecular weights of the B. burgdorferi antigens: 23-25 kDa (Osp C); 31 kDa (Osp A); 34 kDa (Osp B); 39 kDa; 41 kDa; and 83-93 kDa7.

Lane 1, monoclonal antibodies defining selected antigens to B Lane 1, monoclonal antibodies defining selected antigens to B. burgdorferi Lane 2, human serum (IgG) reactive with the 10 antigens scored in the currently recommended criteria for blot scoring; lines indicate other calibrating antibodies. Molecular masses are in kilodaltons.

Treatment Single dose doxycycline shortly after tick bite. Lyme disease give doxycycline followed by amoxacillin Neuroborreliosis requires IV antibiotic therapy.