Hexamita and Giardia as a cause of mortality in congenitally thymus-less (nude) mice.

Two intestinal flagellates, and , were found in high concentrations in most of the congenitally thymus-less (nude) mice in a conventional colony being maintained at the Radiobiological Institute TNO. Antiflagellate therapy markedly reduced mortality, with >50% of the mice living to 110 days. In mice receiving thymus transplants but no antiflagellate treatment the mortality rate was less than in either control or treated mice. In addition, histopathological examination of mice with thymus transplants revealed fewer intestinal flagellates than in control mice. It is suggested that the wasting syndrome seen in nude and neonatally thymectomized mice may be aggravated by infestation with and .