SEROEPIDEMIOLOGY OF EMERGING TICKBORNE INFECTIOUS-DISEASES IN A NORTHERN CALIFORNIA COMMUNITY

A seroprevalence and risk factor study of emerging tickborne infectiou s diseases (Lyme disease, ehrlichiosis, and babesiosis) was conducted among 230 residents of a semirural community in Sonoma County, Califor nia, Over 50% of residents reported finding a tick on themselves in th e preceding 12 months. Samples from 51 (23%) residents were seroreacti ve to antigens from one or more tickborne disease agents: 1.4% to Borr elia burgdorferi, 0.4% to Ehrlichia equi, 4.6% to Ehrlichia chaffeensi s and 17.8% to the Babesia-like piroplasm WA1. Only 14 (27%) of these seroreactive residents reported one or more symptoms compatible with t hese diseases. Seroreactivity was significantly associated with younge r age (<16 years), longer residence in the community (11-20 years), an d having had a physician's diagnosis of Lyme disease, In northern Cali fornia, the risk of infection with these emerging tickborne diseases, particularly in children, may be greater than previously recognized.