USE OF THE POLYMERASE CHAIN-REACTION FOR IDENTIFICATION AND QUANTIFICATION OF THEILERIA-PARVA PROTOZOA IN RHIPICEPHALUS-APPENDICULATUS TICKS

The polymerase chain reaction (PCR) was adapted for detection of Theil eria parva sporoblasts in Rhipicephalus appendiculatus ticks by compar ison with staining of histological preparations of ticks with methyl g reen 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 d issected salivary glands and whole ticks preserved in ethanol. Adult t icks which fed as nymphs on a T. parva infected calf were used in thre e experiments. Firstly, 70 whole ticks divided into 7 batches represen ting the rising and falling parasitaemia of the calf were used to show that detection of infection by the PCR was significantly correlated w ith MGP staining. Secondly, 120 dissected ticks were used from 4 diffe rent batches representative of the overall infection profile within th e ticks to show a high correlation between PCR quantification within t ick salivary glands and MGP count data of the paired gland. Thirdly, 1 20 ticks were used in batches selected for high and low infections. Bl oodmeal contaminants from partially fed adult ticks, present in 60 out of the 120 ticks used, did not inhibit the PCR amplification of T. pa rva DNA. This experiment also showed a great increase in infection det ection in partially fed batches of ticks compared to the untreated bat ches.