Experiments on chickens placed on ground endemic of classical scrub typhus in Akita Prefecture, Japan.

The chicken is available as a bait animal for the study of vector mites and has been found to be infected by chigger mite bite in an area endemic of scrub typhus. L. pallidum and L. palpale were reconfirmed to be zoophilic for the chicken. It is suggested a walking bird can serve as a vector--carrying mites from one place to another. R. orientalis can persist subclinically for a certain period in the spleen and liver of chickens placed on the gound endemic of scrub typhus. Specimens of L. pallidum, 22 in number, collected from chickens placed on the ground of an endemic area in Akita Prefecture were found rickettsia-positive. Both strains isolated from bait chickens and L.pallidum collected from host chickens were identified as a Kato type of R. orientalis.