A PCR-based RFLP analysis of Sarcocystis cruzi (Protozoa: Sarcocystidae) in Yunnan Province, PR China, reveals the water buffalo (Bubalus bubalis) as a natural intermediate host.

A polymerase chain reaction-based restriction fragment length polymorphism (RFLP) approach is used to examine Sarcocystis cruzi-like taxa from the atypical intermediate host, water buffalo, in Yunnan, People's Republic of China. The loci examined lie within the 18S rRNA gene. A total of 15 water buffalo isolates are compared with those of 10 S. cruzi from cattle. RFLP patterns for the S. cruzi isolates from cattle and the S. cruzi-like taxon from water buffalo are found to be identical with all the 12 restriction enzymes used. Interpopulation variation between samples from Kunming and Gengma (Yunnan) is found to be undetectable at these loci for both S. cruzi and the S. cruzi-like taxon. But RFLPs are found between the S. cruzi taxa and S. suihominis from pigs at the same study sites. These findings support the hypothesis that S. cruzi is able to use the water buffalo as an intermediate host and is not restricted to cattle as was previously supposed.