DETECTION OF THEILERIA-ANNULATA BY THE PCR IN TICKS (ACARI, IXODIDAE)COLLECTED FROM CATTLE IN MAURITANIA

We report on the detection of Theileria annulata in infected Hyalomma ticks by the PCR using primers derived from the gene encoding the 30 k Da major merozoite surface antigen (Tams1-1). No inhibition of the PCR was observed and as little as 0.1 pg of parasite DNA, corresponding t o 12 sporozoites, could he detected in non-infected tick DNA samples, spiked with T. annulata genomic DNA. Hyalomma dromedarii ticks, fed on a calf experimentally infected with T. annulata, were used to validat e the PCR further. The infection rate in the adult ticks, fed as nymph s during the febrile reaction, was high (62%), dropped to zero for 1 d ay in tick batches that engorged after treatment with Butalex(TM) and increased to 30% 2 days later and 38% of the ticks acquired the infect ion after feeding as nymphs during; carrier state piroplasm parasitaem ia of less than 0.1%. As an internal control, 16S tick rDNA sequences could je amplified from T. annulata-negative tick samples. Finally, 20 2 adult ticks from Mauritania, collected fi om zebu cattle carrying lo w levels of Theileria piroplasms, were tested by the PCR. Thirty-eight out of 52 (73%) and 17 out of 30 (57%) H. dromedarii from the Gorgol and Trarza regions, respectively and two out of 30 (7%) Hyalomma margi natum rufipes from the Gorgol region were positive. Hyalomma marginatu m rufipes, Rhipicephalus evertsi evertsi and Rhipicephalus guilhoni fr om the Trarza region were negative. These findings confirm that N. dro medarii is the main vector of T. annulata in Mauritania and that the P CR is a useful method of determining the infection rates in ticks coll ected from cattle carrying low levels of T. annulata piroplasms.