Xenodiagnosis After Antibiotic Treatment for Lyme Disease

Lyme disease is the most common vector borne disease in the United States. Although antibiotic therapy is clinically effective in treating the symptoms of Lyme disease for most patients early in the course of disease, a significant number of patients who receive therapy report persistent symptoms. The cause of persistent symptoms after antibiotic therapy for Lyme disease is an area of great controversy. Recent studies have shown that the organism (Borrelia burgdorferi) may persist in animals after antibiotic therapy and can be detected by using the natural tick vector (Ixodes scapularis) to acquire the organism through feeding (xenodiagnosis). Whether this occurs in humans is unknown. Currently available tests for human Lyme disease do not allow determination of persistent infection after antibiotic therapy. We performed the first study of the use of I. scapularis larva for the xenodiagnosis of B. burgdorferi infection in humans. Our pilot study showed that xenodiagnosis was well tolerated with no severe adverse events (AEs). The most common AE was mild itching at the site. In this small pilot study, xenodiagnosis for B. burgdorferi was positive in 2 participants and indeterminate in 2 participants. Further studies are needed to determine the sensitivity of xenodiagnosis in evaluating the infection status of Lyme disease patients. In this proposal, we want to further investigate the utility of xenodiagnosis for identifying persistence of infection with B. burgdorferi in treated human Lyme disease. Our objectives include assessing the link between detection of B. burgdorferi by xenodiagnosis and persistence of symptoms in patients diagnosed with Lyme disease, within 1 year, post therapy; compare the rate of detection of B. burgdorferi by xenodiagnosis after therapy in participants with posttreatment Lyme disease symptoms; identify subject characteristics related to the likelihood of detecting B. burgdorferi by xenodiagnosis including: time from infection, time between infection and therapy, time from therapy; and continue to assess the safety of xenodiagnosis in humans. The results of study have the potential to resolve this long-standing controversy in Lyme disease pathogenesis. While xenodiagnosis is unlikely to be widely used in clinical practice due to the labor intensity and speed of testing, if our study shows a linkage between positive xenodiagnostic testing and persistence of symptoms after B. burgdorferi infection, it may prove to be a useful tool for testing new strategies for treatment and for correlation with more generally applicable diagnostic markers. Understanding the pathogenesis of persistent symptoms following Lyme disease, and identifying reliable diagnostic tests for determining the success of antibiotic therapy, is critical to the medical management of these patients.