Methods for the colonisation of unfed nymphs of Hyalomma subspecies for transmission of Theileria annulata

Abstract

Unfed nymphs of one strain of Hyalomma anatolicum anatolicum Koch, 1844 and two strains of Hyalomma anatolicum excavatum Koch, 1844 were required for further investigations into the development cycle of Theileria annulata Dschunkowsky and Luhs, 1904. On rabbits, these ticks have both two- and three- host cycles and there was evidence of a one-host cycle in one of the H. a. excavatum strains. Rabbits were chosen as hosts because of their ability to produce many ticks. Two methods of modifying the feeding pattern were successfully developed: engorged larvae, which were developing to nymphs on the host, were removed for moulting in the laboratory; newly moulted, two-host nymphs were picked off the rabbits before they could attach. In these two ways large numbers of unfed nymphs were produced but they did not store well. Also when applied to two calves suffering acute T. annulata infection they fed poorly and many died before moulting to adults. The cause of this poor performance on calves was not determined.

Checks were made on the rabbits' health and other than a small, but steady fall in weight, they suffered no ill effects.