Sarcocystis singaporensis Zaman and Colley, (1975) 1976, Sarcocystis villivilliso sp. n., and Sarcocystis zamani sp. n.: development, morphology, and persistence in the laboratory rat, Rattus norvegicus.

Sporocysts obtained in Singapore in the feces of the boid snake, Python reticulatus, were given by mouth to laboratory rats, mice, and a monkey (Macaca mulatta). Infections developed in rats only. Schizonts were observed in vascular endothelium of various tissues of rats examined at 7 to 15 days of infection; and in each of 20 rats examined at 1 mo to 2 yr, cysts of three species of Sarcocystis were observed. Based on observations made by light and electron microscopy, one species was identified as S. singaporensis and redescribed; two species, S. villivillosi and S. zamani, were described as new. The cyst wall of S. singaporensis is thick with tall, stalked, digitiform villi. That of S. villivillosi is moderately thin and bears short, stout villi that are covered with microvilli; and that of S. zamani is thin and bears delicate, branched villi. The cyst of S. zamani is macroscopic with rounded ends; it induces multiplication of host-cell nuclei and causes resorption of the myofibrils. Cysts of the other species are microscopic with fusiform shape that changes markedly with contraction of the host cell. Refrigerated sporocysts of S. singaporensis, S. zamani, and S. villivillosi remained viable for at least 24, 14, and 6 mo, respectively. Sarcocystis singaporensis and S. zamani apparently have been reported previously from several species of Malaysian wild rodents; S. villivillosi represents a unique type in rodents.