Transmission of an unidentified Theileria species to small ruminants by Haemaphysalis qinghaiensis ticks collected in the field

Abstract

The transmission of a recently identified Theileria species pathogenic for sheep and goats in northern China is described. Haemaphysalis qinghaiensis nymphs which had been collected from grass in epidemic areas were able to transmit this Theileria species to sheep. The pathogen was also transmitted to sheep and goats by three batches of adult ticks collected from grass, ticks collected when moving about on sheep and ticks which were found partially engorged on sheep or goats.

Phylogenetic analysis of Theileria species transmitted by Haemaphysalis qinghaiensis

“…described in China was pathogenic to both sheep and goats, Luo and Yin (1997) suggested that there was only one species of Theileria infective for small ruminants and that this was T. lestoquardi. Yin et al (2002a) demonstrated that this parasite could be transmitted by field-collected H. qinghaiensis and confirmed that the tick was the natural vector. Questions arose when attempts to culture schizont infected lymphoblasts in vitro were unsuccessful, since T. lestoquardi has been cultured in vitro and a vaccine was developed in Iran and Iraq (Friedhoff 1997).…”

“…However, recent biological and molecular studies (Schnittger et al 2000;Yin et al 2002aYin et al , 2002bYin et al , 2003 suggested that this parasite could not transform cells in vitro and that schizonts were very difficult to detect in biopsy smears of lymph node. In addition, it was different from T. annulata and T. lestoquardi, and in an inferred phylogenetic tree, the 18S ssrRNA gene sequence of this parasite was most closely related to T. buffeli and clearly divergent from T. lestoquardi and T. annulata.…”

Phylogeny of sheep and goat Theileria and Babesia parasites

“…China, Iran; Luo and Yin 1997;Schnittger et al 2000a;Ahmed et al 2002;Bai et al 2002;Yin et al 2002Yin et al , 2003.…”

Simultaneous detection and differentiation of Theileria and Babesia parasites infecting small ruminants by reverse line blotting

“…Not long ago, it was assumed that only Theileria lestoquardi (formerly T. hirci) is pathogenic for small ruminants (Luo and Yin 1997). However, a number of previously unidentified parasites have been described recently as also pathogenic for small ruminants, among which is a Theileria species causing a fatal disease of small ruminants distributed in North China (Luo and Yin 1997;Schnittger et al 2000aSchnittger et al , 2000bBai et al 2002;Yin et al 2002). This latter parasite is transmitted by Haemaphysalis qinghaiensis and often occurs in mixed infections with other parasites.…”