Prevalence of infection in ticks submitted to the human tick test kit program of the US Army Center for Health Promotion and Preventive Medicine

In 1997, ticks removed from humans and received alive by the Tick-Borne Dis ease Laboratory of the U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM) were tested for pathogens by polymerase chain reaction (PCR). Thirty-three of 222 (15%) Amblyomma americanum (L.) DNAs produced a mplicons of the expected size of Ehrlichia chaffeensis Anderson, Dawson & W ilson and 26/222 (12%) produced amplicons indicating Borrelia burgdorferi J ohnson, Schmid, Hyde, Steigalt & Brenner. Five (2%) appeared to be co-infec ted with both organisms. Thirteen of 308 (4%) Dermacentor variabilis (Say) were POP-positive for spotted fever group rickettsiae. Restriction fragment -length polymorphism analysis indicated all were Rickettsia montane. One hu ndred twenty-seven D. variabilis from Monroe County, WI, were tested for B. burgdorferi and 14 (11%) were positive. Five of 24 (21%) Ixodes scapularis Say were positive for B. burgdorferi and one (2%) was positive for the age nt of human granulocytic ehrlichiosis. Different species of ticks transmit different pathogens, and most tick-borne diseases have similar early sympto ms, therefore knowing the species and infection status of the tick enhances the physician's ability to consider tick-borne agents as a potential cause of disease and recommend appropriate therapy. Ongoing surveillance of the vector species of human diseases provides an additional estimate of human e ncounters, with infected ticks, and testing ticks removed from humans may i ncrease our knowledge of the vector status of tick species for transmitting tick-borne pathogens.