D3007: Assessing Lyme disease risk in dynamic ecotonal communities

Ecotones are transitional zones between habitats that experience unique environmental characteristics and high species diversity. They are identified as risky areas for transmission of vector borne zoonoses which are rising and primarily transmitted by ticks and mosquitoes. Researchers have associated the occurrence of malaria, yellow-fever, and Lyme disease to the ecotone between human settlements and natural habitats. However, in California’s mosaic of ecosystems investigating beyond the urban landscape and understanding the disease dynamics in ecotones between natural environments is important. In western United States, the primary vector for Lyme disease, is Ixodes pacificus, which humans encounter in many habitats including oak-woodlands, chaparral, and grasslands. The most studied habitat has been oak-woodlands, however Borrelia burgdorferi reservoirs also occur in adjacent habitats. The risk in transitional zones between such habitats has not been studied. I will assess Lyme disease risk and characterize tick diversity in ecotonal habitats between oak-woodlands and grasslands. Plots along an oak-woodland and grassland gradient were surveyed for ticks using standard tick drags. Samples were identified and tested for Borrelia infection to determine disease prevalence and nymphal densities across the ecotonal gradient. We found that tick densities increased as you transitioned from grassland to forest in a linear manner possibly responding to favorable environmental conditions. Ecotone habitats also experienced the greatest diversity of tick species and life stages. Understanding these disease dynamics in ecotonal environments is a step forward in prevention. Areas of risk can be more clearly defined, allowing implementation of control measures and protection of the public.