Risk of Lyme disease: perceptions of residents of a Lone Star tick-infested community

Background Lone Star ticks (Amblyomma americanum) have been suggested as a vector of the agent of Lyme disease (Borrelia burgdorferi sensu lato) in th e USA, based on associations with an infection manifesting mainly as erythe ma migrans. In laboratory experiments, however, they failed to transmit B. burgdorferi sensu stricto. Methods In this study, carried out from 1994 to 1996, we determined the ser oprevalences of B.burgdorferi (1.2%), Ehrlichia chaffeensis (7%), F. phagoc ytophila (0%), Rickettsia rickettsii (0%), R. typhi (0%), Coxiella burneti (0%), Francisella tularensis (0%), and Babesia microti (0%) by standard ser ological methods for 325 residents (97% of the total population) of Gibson Island, coastal Maryland, USA, where 15% of the residents reported having h ad Lyme disease within a recent 5-year span. Findings Of the 167 seronegative individuals who were followed up prospecti vely for 235 person-years of observation, only 2 (0.85%) seroconverted for B. burgdorferi. Of 1556 ticks submitted from residents, 95% were identified as Lone Star ticks; only 3% were deer ticks (Ixodes dammini), the main Ame rican vector of Lyme disease. 3. burgdorferis.s. infected 20% of host-seeki ng immature deer ticks and borreliae ("B. lonestari") were detected in 1-2% of Lone Star ticks. Erythema migrans was noted in 65% of self-reports of L yme disease, but many such reports indicated that the rash was present whil e the tick was still attached, suggesting a reaction to the bite itself rat her than true Lyme disease. Sera from individuals reporting Lyme disease ge nerally failed to react to B. burgdorferi or any other pathogen antigens. Conclusion The residents of Gibson island had an exaggerated perception of the risk of Lyme disease because they were intensely infested with an aggre ssively human-biting and irritating nonvector tick. In addition, a Lyme dis ease mimic of undescribed etiology (named Masters' disease) seems to be ass ociated with Lone Star ticks, and may confound Lyme disease surveillance. T he epidemiological and entomological approach used in this study might frui tfully be applied wherever newly emergent tickborne zoonoses have been disc overed.