Prevalence and genetic relatedness of Besnoitia besnoiti isolates from different geographical regions of South Africa.

Abstract

Bovine besnoitiosis is a protozoan disease caused by an apicomplexan parasite Besnoitia besnoiti and is reportedly re-emerging in Europe and occurring in many other countries including South Africa. The disease has long been neglected and has only recently started getting attention due to its increasing geographical distribution. This parasite causes significant economic losses due to reduced body condition, declined milk production, irreversible sterility in males and mortality. This study was conducted to determine the prevalence of Besnoitia besnoiti infection in cattle, as well as to establish the phylogenetic relationship among parasite isolates in different geographical regions of South Africa, where the disease was previously reported. A total of 688 cattle (688 blood and 376 skin samples) were randomly sampled from farms located in Limpopo, Gauteng, KwaZulu-Natal and Eastern Cape provinces of South Africa. Based on the analyses of DNA sequences of the nuclear ribosomal internal transcriber spacer 1 (ITS1), it was observed that 15.7% (108/688) of the sampled animals were positive, with 5.3% (20/376) and 14.4% (99/688) of the animals being positive on skin and blood samples, respectively. 2.9% (11/376) of the animals were positive on both blood and skin samples. The difference between in prevalence between the areas sampled were not significant, χ² = 0.263. The parasite was more prevalent in communal farms (30.8 %) and in exotic breeds (35.3 %) than local or mixed breeds, and the difference in prevalence between farming and breed type were not significant (χ² = 0.199, χ² = 0.227 respectively). Aligned sequences were analysed by Maximum parsimony, neighbour joining and maximum likelihood and phylogenetic analysis of the isolates was carried out. Results showed that, based on the ITS1 region, our isolates were closely related to the wildebeest strain which is currently used for the manufacture of the vaccine, forming a clade which is separate from the European strains. One of the isolates from Gravelotte, Limpopo province, was closely related to the European strains, forming a sister clade for the European strains from GenBank. This is the first report on molecular characterisation of the parasite in South Africa and will aid in disease surveillance and control in the studied areas.