Tropical rat mite dermatitis: Case report and review

Six medical students inhabiting a centuries-old, rat-infested house in Lube ck, in northern Germany, were suffering from itching papules and seropapule s. Prior to these patients' visit to our institute, their conditions had be en diagnosed as pediculosis, scabies, or pulicosis and treated unsuccessful ly with the antiparasitic agent lindane (0.3%). The final diagnosis, tropic al rat mite dermatitis, was based on the identification of the arthropod Or nithonyssus bacoti, which has an unsegmented body with eight legs. No treat ment was recommended, and the dermatitis disappeared within 2 weeks. Measur es taken to prevent reinfestation included extermination of the rats and tr eatment of the rooms of the house with the acaricide benzyl benzoate. Becau se the mite O. bacoti spends a relatively short time on a host and penetrat es the skin for feeding only, the application of an antiparasitic agent is not necessary. If indicated, treatment should be symptomatic.