RESUMO
Skin lesions, consisting of nonspecific bites with intense pruritus and excoriation of the skin, were found on personnel working in an animal colony primarily housing mice. The tropical rat mite, Ornithonyssus bacoti, was diagnosed from mites trapped on insect-monitoring sticky traps and collected from mouse cages in the colony. Because these mites do not live on mice but only come to feed when the animals are in their nest, an initial attempt was made to eliminate the mites with a thorough cleaning of the facility. Clidox foam was applied to the entire room with a foaming machine. Then the mice were transferred into the sanitized cages in the cleaned room. The numbers of mites were reduced to the point that they were no longer noticed in the colony, but the mites returned within 2 weeks. The mites were successfully eliminated with the use of permethrin-impregnated cotton balls in the mouse cages for 8 weeks and treatment of the premises. Treatment of the premises included spraying floors and walls of all rooms housing mice and adjacent hallways in the colony with pyrethrin spray by a commercial pest control company. To prevent one room of rabbits from maintaining the infestation, they were treated weekly with an organic pyrethrin dust. Insect sticky traps have remained negative for mites for more than 3 years after treatment.