The polymerase chain reaction (PCR) was adapted for detection of Theileria parva sporoblasts in Rhipicephalus appendiculatus ticks by comparison with staining of histological preparations of ticks with methyl green and pyronin (MGP). Two 32mer primers (IL174 and IL179) were used to amplify Theileria parva (Muguga isolate) DNA from the TPR 1 region of the genome by the PCR. Detection of T. parva was carried out with dissected salivary glands and whole ticks preserved in ethanol. Adult ticks which fed as nymphs on a T. parva infected calf were used in three experiments. Firstly, 70 whole ticks divided into 7 batches representing the rising and falling parasitaemia of the calf were used to show that detection of infection by the PCR was significantly correlated with MGP staining. Secondly, 120 dissected ticks were used from 4 different batches representative of the overall infection profile within the ticks to show a high correlation between PCR quantification within tick salivary glands and MGP count data of the paired gland. Thirdly, 120 ticks were used in batches selected for high and low infections. Bloodmeal contaminants from partially fed adult ticks, present in 60 out of the 120 ticks used, did not inhibit the PCR amplification of T. parva DNA. This experiment also showed a great increase in infection detection in partially fed batches of ticks compared to the untreated batches.

Pathological effects have been demonstrated in a number of arthropod species as a consequence of parasitic infection. This is usually manifest as reduced arthropod survival and/or fecundity. This paper describes the detrimental effects the protozoan parasite, Theileria parva has on Rhipicephalus appendiculatus ticks. R. appendiculatus ticks were dissected and sectioned at regular intervals during their nymph to adult moult after detaching from a T. parva infected calf, and assessed by light and electron microscopy. The reproductive capacity of the T. parva infected ticks was also compared with that of control, uninfected ticks. The number of T. parva forms seen during the ticks' moult were recorded and showed a substantial reduction as the moult progressed. A non-linear relationship between piroplasm ingestion by the engorged nymph and eventual adult salivary gland infection levels was shown. Tick gut and salivary gland pathology was noted at various stages throughout the moult and correlated with the parasite burdens in the affected organs at those timepoints. The reproductive performance of infected ticks was greatly impaired compared to controls. Infected female ticks had longer bloodmeal engorgement times, reduced bloodmeal volumes, smaller egg batch weights and greatly decreased egg hatching success. The pathological effects are discussed in relation to parasite population dynamics within the ticks and compared with similar examples of pathology evidenced with other parasite infected arthropod species.

Theileria parva is a hemoprotozoan parasite responsible for causing East Coast fever in east and central Africa. The vaccine currently available is an "infection and treatment" procedure which involves the injection of live sporozoites followed by drug therapy to prevent clinical illness. Before introducing potentially new strains of parasite into an area, however, it is crucial to check the disease situation in the field first. We looked at three different areas in Kenya: Limuru in which many cattle have already been vaccinated and Kitale and Kakamega which so far have not been vaccinated. Genus and species specific primers were used to test for the presence of Theileria species in blood and tick samples collected from the three areas. Limuru showed a cattle and tick infection prevalence of 27% and 2.3% respectively with T. parva. Kitale showed a cattle and tick infection prevalence of 100% and 14.2% respectively while Kakamega showed 100% and 0% respectively. Reasons for variations between areas involving vaccination status and epidemiological data are discussed.

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