The effect of flea control on Yersinia (Pasteurella) pestis antibody rates in the California vole, Microtus californicus, and its epizootiological implications.

The effects of flea control on the prevalence of (Pasteurella) pestis antibody rates in the California vole, Microtus californicus, were studied in San Mateo County, California, USA. In this area, which had shown antibody prevalence rates of 50% or more during epizootics in previous years, continuous flea control measures reduced the antibody rate to virtually zero and held it at that level for 12 months, although a nearby area showed an incidence of 40-80% seropositive voles for 5 months during the same period. The striking correlation between the reduction of the flea population and the decline of Y. pestis antibody rates suggests that in the area studied there is no evidence that soil, or any factor other than the flea vector, was the agent of transmission of the infective agent in wild rodents.