A devastating plant pathogen, Phytophthora ramorum, which causes the disease Sudden Oak Death (SOD), is sweeping through oak woodlands of California. This new disease has the potential to profoundly affect local vertebrate populations. Vertebrate populations (e.g., mice, squirrels, lizards), in turn, strongly influence risk of human exposure to Lyme disease (LD) via their impacts on numbers and infection of tick vectors. This research will integrate field, laboratory, and modeling efforts. First, a combination of field and lab studies will furnish information on individual host species' contributions to LD risk in California. Second, the abundance of specific groups of vertebrates will be compared in sites of high versus low SOD impact. Third, responses by specific hosts to SOD will be used to construct models to predict how SOD will change risk of human exposure to LD. Fourth, specific hypotheses arising from these models will be tested by assessing tick abundance and infection prevalence in areas of high and low SOD impact.
Our research embeds the ecology of the most prevalent vector-borne disease of humans in the United States (LD) within the ecology of a devastating infectious disease of plants (SOD), and specifically asks how these two disease systems interact. The outbreak of SOD presents a novel opportunity to determine how a human infectious disease is impacted by an exotic forest pathogen. Such research provides a model for current epidemics of plant pathogens and pests (e.g., beech bark disease, hemlock woolly adelgid, gypsy moth) that in all likelihood will dramatically change the composition of North American forests, with potentially strong consequences for human health.
