Light microscopic and ultrastructural studies on Sarcocystis spp. infection in Philippine water buffaloes (Bubalus bubalis)

In a survey for sarcocysts in muscle tissues obtained from 142 water buffaloes (Bubalus bubalis）, 92(64.8%) carcasses had sarcocysts. Macroscopic and two forms of microscopic cysts, the spindle-shaped or fusiform cysts commonly occurring in the muscles of the esophagus, throat and limbs, and the globular to oval cysts which were the dominant form in the diaphragm and cervical muscle tissue were noted. Ultrastructural analysis of macroscopic and microscopic cysts and their cyst wall revealed two distinct species of Sarcocystis infecting Philippine water buffaloes. These are the macroscopic species, Sarcocystis fusiformis which has been previously reported in the country possessing highly-dendritic cauliflower-like projections emanating from the primary cyst wall, with annulated microfibrils and numerous electron dense granules; and the newly redescribed Sarcocystis levinei (Dissanaike and Kan 1978; Huong, Dubey and Uggla 1997b) exhibiting a cyst wall with numerous, minute hair-like villar protrusions with expanded or dome-shaped base, an intermediate finger-like, and distal tapering segments which at some points join to form conical tufts. Our findings represent the first report of S. levinei in Philippine water buffaloes supported with ultrastructural analysis of the sarcocyst and its cyst wall, and likewise refute earlier published reports that all microscopic cysts in Philippine water buffaloes are developing forms of S. fusiformis.