Spotted fever group rickettsiae or Borrelia burgdorferi in Ixodes cookei (Ixodidae) in Connecticut.

Immatures and females of Ixodes cookei, a hard-bodied tick, were collected from woodchucks and other mammals in the northeastern United States and examined for spotted fever group rickettsiae and Borrelia burgdorferi. Of the 93 nymphs analyzed by a hemolymph test, 4 (4.3%) harbored rickettsiae. Six (15%) of 40 females were also infected. All infected ticks were collected from woodchucks in Connecticut. Indirect fluorescent antibody staining of midgut tissues from 128 nymphs revealed B. burgdorferi in two (1.6%) ticks, whereas larval and female ticks were negative. Further consideration should be given to I. cookei as a possible vector of spotted fever group rickettsiae or spirochetes that cause Lyme borreliosis.