Phylogenetic analysis of Sarcocystis nesbitti (Coccidia: Sarcocystidae) suggests a snake as its probable definitive host.

Sarcocystis nesbitti was first described by Mandour in 1969 from rhesus monkey muscle. Its definitive host remains unknown. 18S rRNA gene of S. nesbitti was amplified, sequenced, and subjected to phylogenetic analysis. Among those congeners available for comparison, it shares closest affinity with those species of Sarcocystis which use snakes as definitive hosts. We therefore hypothesize that a snake may serve as the definitive host for S. nesbitti.