Volume 30, Issue 3
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



To compare rickettsial infectivity and seropositivity rates against spotted fever group (SFG) rickettsiae, ticks and wild mammals were collected from three areas where was thought to be enzootic in Connecticut during 1978–1979, and from four additional sites (with no reported human cases) between 1976 and 1979. Of the 1,001 examined by the hemolymph test, 59 (5.9%) contained rickettsia-like organisms; direct immunofluorescence tests verified the presence of SFG rickettsiae in 14 specimens. Prevalence of rickettsiae-infected ticks at Newtown, an area where human cases of Rocky Mountain spotted fever probably originated, was 2.2%. Rates for six other areas ranged between 0 and 6.3%. Isolations included from four ticks collected at Branford and Woodbridge, and (R-like strain) from the blood of an acutely ill person. Microagglutination (MA) tests indicated that 15 (14.9%) of 101 (white-footed mice) from Newtown had agglutinins in titers ⩾1:8 against , whereas five of 92 white-footed mice (5.4%) from Branford, West Hartford, Woodbridge, and Sharon were considered MA-positive. Indirect microimmunofluorescence tests of (raccoon) sera revealed antibodies to in 33 of 69 (47.8%) samples from Newtown and in two of 60 (3.3%) from Guilford. Additionally, 17 raccoons had sera specific to (n = 8) or to the 369-C rickettsia strain (n = 9). Since rickettsia-positive ticks and high-titered seropositive mammals occurred at widely separated sites in Connecticut, there are probably several foci of SFG rickettsiae distributed throughout the range.


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