DNA PROBES DETECT THEILERIA-PARVA IN THE SALIVARY-GLANDS OF RHIPICEPHALUS-APPENDICULATUS TICKS

The ability of Theileria parva-specific DNA probes to detect T. parva sporoblasts and sporozoites in samples prepared from the salivary glands of infected Rhipicephalus appendiculatus ticks was evaluated. The two DNA probes used, pgTpM-23 and lgTpM-58, were selected from a genomic library of T. parva (Muguga) piroplasm DNA. In all, 25-200 adult ticks infected with each of 6 different T. parva stocks were tested. One salivary gland from each tick was processed for DNA hybridization, whereas the other was stained and examined by light microscopy to determine the number of infected acini. The correlation for the detection of infected acini between the two methods was 90%-100% for both probes, except when the pgTpM-23 probe was hybridised to salivary glands from ticks infected with the Mariakani stock of T. parva (84% correlation). The discrepancy lay within the range expected, based on the observation that in 12.5% of the ticks, only one salivary gland was infected. The probes did not hybridize to salivary glands from uninfected ticks.