Ticks of small ruminants in China.

The importance of ticks and tick-borne diseases of small ruminants in China is discussed. Of the 109 species of ticks identified to date in China, 45 species infest small ruminants. Five species have been proved to be involved, or possibly involved, in the transmission of tick-borne diseases. Anaplasma ovis, Babesia motasi, Babesia ovis and two unidentified species of Theileria, have been recorded in small ruminants in China. The diseases caused by these organisms are widespread in China, causing great economic losses, estimated at approximately 70 million USD per annum. Anaplasmosis occurs from September to March in Inner Mongolia and during spring in other areas. Babesiosis and theileriosis occur in March to June in northwestern China. The vectors of A. ovis are Dermacentor nuttalli, Hyalomma asiaticum and Rhipicephalus pumilio. These three species of ticks do not appear to transmit A. ovis transstadially or transovarially, but rather through movement of partially engorged, infected adult ticks from A. ovis carrier animals. The vector ticks of the two species of Babesia have not been very well documented, but at least two species of Haemaphysalis are thought to transmit them. Haemaphysalis qinghaiensis transmits the two as yet unidentified species of Theileria transstadially. Priorities for future research on these diseases are summarised.