Investigations into the carrier-state of sp. (buffalo) in cattle.

The are apicomplexan parasites transmitted by ticks to vertebrate hosts. Most species exhibit some form of host or vector specificity, since under endemic conditions only a limited number of tick species act as vectors and not all vertebrate hosts are able to maintain a persistent carrier state. Data for sp.

Corridor disease (buffalo-associated Theileria parva) outbreak in cattle introduced onto a game ranch and investigations into their carrier-state.

East Coast fever (Theileria parva infection in cattle) was eradicated from South Africa in the mid-1900. However, another form named Corridor disease (CD), associated with T. parva carrier buffaloes exists and outbreaks have increased in endemic areas.

Efficacy of South African Babesia bovis vaccine against field isolates.

A high-passage Babesia bovis vaccine containing only one genotype population was, although protective, inferior compared to the immunity afforded by a lower passage of the same strain containing two populations. The 24 times serially passaged South African B. bovis S vaccine strain contain only a single parasite population (Bv80 allele A 558bp).

Co-transmission of the non-transmissible South African Babesia bovis S24 vaccine strain during mixed infection with a field isolate.

The South African Babesia bovis live blood vaccine, originating from a field isolate attenuated by 23 serial syringe passages in splenectomized calves, has lost the ability to infect the natural vector Rhipicephalus (Boophilus) microplus. In this study, infection with mixed parasites from the vaccine strain and a field isolate, resulted in transmission of both genotype populations. Comparing the field isolate and transmitted combination indicated no significant difference in their virulence, while challenge of vaccinated cattle with these isolates showed the ability of the vaccine to protect against both.

Genotypic diversity in Babesia bovis field isolates and vaccine strains from South Africa.

Genotypic diversity in Babesia bovis (cause of Asiatic redwater in cattle) vaccine strains and field isolates from South Africa were investigated using the Bv80 gene as well as microsatellites. The S11 vaccine strain possessed both A and B alleles of the Bv80 gene, as well as genotypic diversity within each allele type as defined by repeat variation resulting in different amplicon sizes. Rapid serial passage of vaccine strain from passage S10 to S24 resulted in loss of genotypic diversity that yielded a single allele A genotype with an amplicon size of 558 bp.