Rickettsia rickettsii and Rickettsia montana from Ixodid ticks in Connecticut.

Dermacentor variabilis, infected with spotted fever group rickettsiae, parasitized 8 of 70 raccoons captured in Newtown, Connecticut. The spotted fever agent, Rickettsia rickettsii, was isolated and identified from 4 adult D. variabilis and from 1 nymphal Ixodes texanus removed from raccoons. This verifies the presence of this etiologic agent in ticks in an area where 6 people had clinical signs and symptoms of Rocky Mountain spotted fever (RMSF) and antibodies to R. rickettsii. These are the first isolations of R. rickettsii from D. variabilis in southern New England and the first identified rickettsiae from I. texanus. No rickettsiae were isolated from Ixodes muris or I. cookei. Rickettsia montana was recovered in Vero cell culture from a D. variabilis collected in East Haddam, Connecticut where RMSF is not known to be prevalent.