PCR detection and genetic diversity of bovine hemoprotozoan parasites in Vietnam

Abstract

Hemoprotozoan infections often cause serious production losses in livestock. In the present study, we conducted a PCR-based survey of Babesia bovis, Babesia bigemina, Theileria annulata, Theileria orientalis, Trypanosoma evansi and Trypanosoma theileri, using 423 DNA samples extracted from blood samples of cattle (n=202), water buffaloes (n=43), sheep (n=51) and goats (n=127) bred in the Hue and Hanoi provinces of Vietnam. With the exception of T. annulata and T. evansi, all other parasite species (B. bovis, B. bigemina, T. orientalis and T. theileri) were detected in the cattle populations with B. bovis being the most common among them. Additionally, four water buffaloes and a single goat were infected with B. bovis and B. bigemina, respectively. The Hue province had more hemoprotozoan-positive animals than those from the Hanoi region. In the phylogenetic analyses, B. bovis-MSA-2b, B. bigemina-AMA-1 and T. theileri-CATL gene sequences were dispersed across four, one and three different clades in the respective phylograms. This is the first study in which the presence of Babesia, Theileria and Trypanosoma parasites was simultaneously investigated by PCR in Vietnam. The findings suggest that hemoprotozoan parasites, some of which are genetically diverse, continue to be a threat to the livestock industry in this country.

Fig. 1.

Phylogenetic analysis of B. bovis-MSA-2b gene sequences. Sequences generated in the present study (n=5) are indicated by boldface-type letters. Note that the Vietnamese sequences fall into four different clades.

Fig. 2.

Phylogenetic analysis of B. bigemina-AMA-1 gene sequences. Sequences generated in the present study (n=5) are indicated by boldface-type letters. Note that all the Vietnamese sequences are in clade 2.

Fig. 3.

Phylogenetic analysis of T. theileri-CATL gene sequences. Sequences determined in the present study (n=5) are indicated by boldface-type letters. Note that the Vietnamese sequences fall into three different sub-clades. Because the two Cameroon sequences (HQ664748 and HQ664750) were found in previously described ThaiIIa [12], this sub-clade has been renamed TthIID in the present study.