- A genus of bird and rodent mites; species include O. bacoti, the tropical rat mite, a possible vector of murine typhus and a cause of human dermatitis; O. bursa, the tropical fowl mite; and O. sylviarum, the northern fowl mite. [G. ornis (ornith-), bird, + nyssus, to prick]
* * *Or·ni·thon·ys·sus .ȯr-nə-'thän-ə-səs, -thə-'nis-əs n a genus of mites (family Macronyssidae) that are parasitic on vertebrates and include the rat mite (O. bacoti) and two serious pests (O. bursa and O. sylviarum) of domestic fowl
* * *Or·ni·tho·nys·sus (or″nĭ-tho-nisґəs) a genus of mites of the family Dermanyssidae; formerly called Liponyssus.
Medical dictionary. 2011.