Ixodes scapularisandBorrelia burgdorferiAmong Diverse Habitats Within a Natural Area in East-Central Illinois

Abstract

The distributions of the tick vector, Ixodes scapularis, and of the etiologic agent of Lyme disease, Borrelia burgdorferi (Bb), have continued expanding in Illinois over the past 20 years, but the extent of their spread is not well known. The role of multiple habitats in the establishment and maintenance of I. scapularis and Bb at local scales is not well understood, and the use of integrated approaches to evaluate local scale dynamics is rare. We evaluated habitat diversity and temporal changes of I. scapularis occurrence and Bb infection within a natural area in Piatt County, Illinois, where I. scapularis were first detected in 2002. Small mammals were trapped and attached ticks were collected in young forest, prairie, mature forest, and flood plain sites from 2005 to 2009. Small mammal abundance, and the prevalence (% mammals infested), mean intensity (I. scapularis per infested mammal), and relative density (I. scapularis per mammal trapped) of I. scapularis were computed for each habitat type and compared. Immature I. scapularis were tested for Bb infection using polymerase chain reaction techniques. Out of 2446 trapped small mammals, 388 were infested with I. scapularis. The prairie had the highest diversity of small mammal hosts. Prevalence, mean intensity, and relative density of I. scapularis and prevalence of Bb infection were highest for the prairie and young forest sites; in the former, all infection was associated with the prairie vole, Microtus ochrogaster. The minimum Bb infection prevalence of on-host I. scapularis collected in the natural area was 14% (n=56). Unlike previous studies solely focused on forested areas and Peromyscus leucopus, our study is the first to provide evidence of I. scapularis collected from prairie habitat and other reservoir hosts, particularly M. ochrogaster.