Preliminary findings and molecular characterization of thin-walled Sarcocystis species in hearts of cattle and buffaloes in Thailand, Lao PDR, and Cambodia.

Cattle and buffaloes, popular protein sources worldwide, are intermediate hosts for several Sarcocystis species. These coccidian protozoans cause sarcocystosis resulting in subclinical and chronic infections in striated muscles by forming macrocysts or microcysts. In Thailand, Lao People's Democratic Republic, and Cambodia, Sarcocystis species have been reported, but molecular identification has been lacking. This study investigates the prevalence of infection, histo-morphology, and molecular identification of Sarcocystis species in hearts of cattle and buffalo sold in local markets. A phylogenetic tree inferred from a portion of the 18S ribosomal (r) RNA gene was used to identify the genus and species of Sarcocystis. The mitochondrial cytochrome c oxidase subunit 1 (cox-1 gene) was sequenced to confirm the species of host tissue. In Thailand, Sarcocystis was detected in 66.7% (14/21) of samples. In Lao People's Democratic Republic, 90% (9/10) of samples were infected and in Cambodia 100% (8/8). For the first time from these countries, we report Sarcocystis cruzi, Sarcocystis heydorni, and Sarcocystis levinei found in taurine cattle (Bos taurus) and water buffalo (Bubalus bubalis). Zoonotic protozoan transmission needs to be controlled by inspection activities by local health inspectors, and appropriate action is required at all points in the food chain by competent authorities to protect consumer health and prevent sarcocystosis in cattle and water buffaloes.