(Ornithonyssus bacoti), a parasitic tick of the gama-sid group. Body length, to 1.1 mm.
The mouth parts of the rat tick are adapted to bloodsucking. The tick is very widely distributed (in the USSR, mainly in port cities). The rat tick parasitizes rats and mice (more rarely, other rodents), proliferating in their nests. During periods of massive reproduction they may attack humans, causing severe skin irritations (dermatoses) with their bites. Control measures involve disinfesting the premises with insecticides and destroying unwanted rodents.