Population exposure assessments for Lyme disease are critical in order to focus public health education and to control the distribution of Lyme borreliosis in the community as a whole. We hope to improve such assessments by examining Ixodes pacificus abundance and infection prevalence as indicators of risk of Borrelia transmission to humans in various habitats over time. We evaluated four vegetational habitats for both nymphal and adult Ixodes pacificus abundance and infection prevalence in southern Mendocino county; this poster presents preliminary results of this assessment. The four major habitats (mixed hardwood, woodland grass, open grasslands, and chaparral) within the 3200 acre Hopland Research and Extension Center (HREC) were dragged for ticks in 2000 and 2001 during peak nymphal and adult I. pacificus activity. Ten to fourteen sites were evaluated for each habitat type, paired by aspect (northern and eastern exposures or southern and western exposures). Aspect is an important variable to examine given the high humidity requirements and temperature sensitivity of the vector tick. A total of forty-eight sites were tested, each evaluated on four and ten separate occasions for each nymphal season and for the single adult season conducted to date, respectively. While nymphal ticks have been the primary life stage implicated in Lyme borreliosis, adults may locally play a significant role based on differential human exposure to various habitats throughout the year; consequently collections were made for nymphs from May-June and for adults from December to April. Ticks were identified to genus and species, then tested for Borrelia burgdorferi infection using direct immunoflourescence analysis (DFA). Results are presented for the effect of aspect and habitat type on tick densities, relative infection prevalence in different habitat types, and variability of abundance and infection prevalence within each habitat type.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA