October 2022

​Gerbil with an itch

A Bushy Tailed Jird/Gerbil was presented to Texas A&M college of veterinary medicine with a two-week history of progressive pruritus on the left ear. The pruritus progressed to the point where the external ear was scabbed and scratched till it was raw (Image 1). The gerbil was not on any medication or prevention and no other animals in the same cage appeared affected. Several specimens, as the one observed on the following images were collected from the gerbil (Image 2-3).

Image 1: Lesion on ear of gerbil
Image 2-3: Specimens collected from gerbil

This month’s case was a contribution of Tiana Sanders and Dr. Gui Verocai.

What's your diagnosis?

​Ornithonyssus bacoti. Known as the “tropical rate mite” is a bloodsucking mesostigmatid mite. They can be distinguished from Liponyssoides sanguineus, another mite that typically parasitizes rodents, by observing an anterior anus within the anal plate compared to a centrally located anus in Liponyssoides. Liponyssoides also has long whip-like chelicerae whereas Ornithonyssus have well-developed chelicerae that are the same in diameter throughout. Ornithonyssus is zoonotic and results in “Tropical Rat Dermatitis” in humans. It also harbors other pathogenic agents such as Francisella tularensis, Yersenia pestis, Borrelia burgdorferi and Rickettsia typhi.