High prevalence of infection with Entamoeba dispar, but not E-Histolytica,in captive macaques

A total of 268 nonhuman primates (20 species) kept in the Primate Research Institute, Kyoto University, Japan, were surveyed for intestinal amebas. To tal positive rates as based on the presence of cysts in the stool following formalin-ether sedimentation were as follows: Entamoeba histolytical/E. di spar, 53%; E. coli, 34%; E. hartmanni, 34%; Iodamoeba buetschlii, 25%; Endo limax nana, 8%; and E. chattoni, 3%. Positive rates were higher in Old Worl d monkeys and lower in New World monkeys. Ail the 141 E. histolytica/E. dis par-positive animals were Macaca monkeys. The E. histolytica/E. dispar-posi tive samples were analyzed by polymerase chain reaction (PCR) for identific ation of E. histolytica and E. dispar. E. dispar DNA was detected in 137 sa mples, whereas no E. histolytica DNA was seen. Zymodeme analysis and reacti vity to monoclonal antibodies of cultured trophozoites also supported the p resence of E. dispar and the absence of E. histolytica. When the sera of 93 macaques were examined by an indirect fluorescent antibody test, only 3 an imals proved to be positive for E. histolytica, showing the lowest titer. T hese results demonstrate that infection with E. dispar, but not E. histolyt ica, is predominant in macaques.