Prevalence and genetic diversity of piroplasm species in horses and ticks from Tunisia.

The genetic diversity and prevalence of Babesia and Theileria species in the equine population of Tunisia were studied using reverse line blot (RLB) hybridization on blood samples and unfed adult ticks collected from apparently healthy horses from three bioclimatic zones in Tunisia. Piroplasms were identified in 13 of 104 of the horse blood samples analyzed (12.5%) and five genotype groups were identified: Theileria equi group A (nine animals, 8.7%), group C (one animal, 1.0%) and group D (three animals, 2.9%), and Babesia caballi groups A and B (one animal each). All horses from the semi-arid zone were negative and prevalence in the humid and sub-humid zones were 12.9% and 20.0%, respectively. Three Ixodid tick species (Hyalomma marginatum, Hyalomma excavatum and Rhipicephalus bursa) were collected from examined horses and equine piroplasms were detected in 10.8% of them. T. equi groups A and D (9.2%), and B. caballi group B (1.6%) were identified in ticks. This work represents the first epidemiological report of equine piroplasmosis in Tunisia. Results showed a high level of diversity within the 18S rRNA gene of equine piroplasm species, and confirmed the presence in Tunisia of two T. equi genetic groups, C and D, only reported before in South Africa and Sudan.