Capillaria hepatica (Bancroft) in select rat populations of Hartford, Connecticut, with possible public health implications.

Capillaria hepatica was found in 82% of 86 Norway rats (Rattus norvegicus) trapped in Hartford, Connecticut between February and November 1975. Adults were parasitized more frequently than juveniles and infection rate did not differ between sexes. Rats demonstrated a low intensity of infection, with 9% having extensive liver involvement. A seasonal variation in infection rate may have been a manifestation of environmental factors, cannibalism, and predation.