Tropical Rat Mite Dermatitis: Case Report and Review

Abstract

Six medical students inhabiting a centuries-old, rat-infested house in Lübeck, in northern Germany, were suffering from itching papules and seropapules. Prior to these patients' visit to our institute, their conditions had been diagnosed as pediculosis, scabies, or pulicosis and treated unsuccessfully with the antiparasitic agent lindane (0.3%). The final diagnosis, tropical rat mite dermatitis, was based on the identification of the arthropod Ornithonyssus bacoti, which has an unsegmented body with eight legs. No treatment was recommended, and the dermatitis disappeared within 2 weeks. Measures taken to prevent reinfestation included extermination of the rats and treatment of the rooms of the house with the acaricide benzyl benzoate. Because the mite O. bacoti spends a relatively short time on a host and penetrates the skin for feeding only, the application of an antiparasitic agent is not necessary. If indicated, treatment should be symptomatic.

Tropical rat mites (Ornithonyssus bacoti) – serious ectoparasites

“…If the tropical rat mite plays a role as vector for various diseases is unknown. In the literature infestations of rodents and humans, too, with Ornithonyssus bacoti manifesting clinically as ictus reactions have been reported [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. As it is a parasite active at night, predominantly skin regions not covered by tight clothing are affected.…”

Outbreak of Tropical Rat Mite <i>(Ornithonyssus bacoti)</i> Dermatitis in a Home for Disabled Persons

“…hominis, which burrow tunnels into the skin of their host. However, sometimes humans are also vulnerable to less frequently recognized forms of dermatitis caused by ectoparasites parasitic on various animals [15,16,17,18]. These dermatoses are often misdiagnosed as prurigo simplex, allergy, unspecific mosquito insect bites or bacterial folliculitis.…”

Acarosis y zoonosis relacionadas

“…La larva pasa a protoninfa con cuatro pares de patas, se alimenta de sangre y posteriormente pasa a deutoninfa, que no se alimenta y es la que se transforma en adulto en un plazo de 24 horas. Ocasionalmente se describe un ciclo reproductivo partenogenético 39 . El ciclo dura entre 11 y 16 días, pudiendo generar grandes poblaciones en corto tiempo 2 .…”

“…La mayoría de las veces se captura a la hembra, que ingurgitada puede alcanzar el tamaño de 1 cm, lo que facilita su visualización 43 . Morfológicamente es similar a D. gallinae y O. sylviarum, se diferencia por presentar gran cantidad de pelos en la zona abdominal, un ápice caudal grueso y un escudo ovo genital con un ano en posición craneal 39 . Los principales diagnósti-cos diferenciales son: escabiosis, acarosis ocasionadas por otros animales, pulicosis, prúrigo insectario y pediculosis corporis entre otros.…”