Mammomonogamus nematodes in felid carnivores: a minireview and the first molecular characterization.

Five of the 13 known species of Mammomonogamus have been described in members of the family Felidae, including domestic cats, making felids the most frequent hosts of Mammomonogamus. The occurrence of Mammomonogamus in felids is geographically scattered and information on the life cycle and other aspects of infections is lacking. The paucity of data opens the questions on possible conspecificity of some of the described species of Mammomonogamus and on the existence of possible reservoirs for infections in domestic cats in geographically isolated endemic foci of infection. To test such hypotheses, we compared sequences of mitochondrial and nuclear markers obtained from Mammomonogamus adults or eggs collected from domestic cats in three geographically distant localities. Based on morphology, geographic origin and site of infection, the worms examined can be referred to as Mammomonogamus ierei and Mammomonogamus auris. Phylogenetic analyses of both mitochondrial and ribosomal DNA markers showed monophyly of the genus Mammomonogamus and suggested the existence of at least two species in cats. Review of the literature, the existence of several species and the discontinuous geographic distribution of Mammomonogamus infections in domestic cats suggest an historical spillover of infection from wild reservoirs, presumably wild felids.

Mammomonogamus auris infection in the middle ear of a domestic cat in Saipan, Northern Mariana Islands, USA.

A 2-year-old female domestic shorthair cat on the island of Saipan was presented to a local veterinarian for headshaking. Otoscopic examination showed mild erythema of the right tympanic membrane, but was otherwise unremarkable. Headshaking resolved with topical gentamicin/betamethasone/clotrimazole therapy; however, erythema persisted. Further otoscopy revealed movement of the erythematous region, which was in fact the red-colored strongylid nematode, Mammomonogamus auris, residing within the middle ear. Myringotomy and a saline flush were performed under heavy sedation. A silastic tube was inserted into the incision and the worms were retrieved by applying negative pressure. Follow-up treatment included topical thiabendazole/dexamethasone/neomycin ointment as well as selamectin. Mammomonogamus auris has previously been documented only three times, once each in China, Sri Lanka and Japan. This is the first report of M auris in cats from Saipan.