Effects of temperature on morphologic variation of Schizotrypanum cruzi in tissue culture

A strain of Schizotrypanum cruzi, isolated from an acute case of Chagas' disease, was inoculated into cultures of "L" cells. Some infected tissue cultures were kept at 26 ± 2 ° C and some at 37 ± 0.5 ° C. At 37 ° C both intra- and extracellular forms of S. cruzi were similar to those found in the infected mammals. At 26 ° C the intra- and extracellular forms were strikingly different from the corresponding ones at 37 ° C. The extracellular forms at 26 ° C are similar to the so-called metacyclic forms found in the hind gut of the invertebrate host. The hypothesis is presented that temperature alone is the factor responsible for the morphological differences observed and that the slender forms occasionally present in the blood of vertebrates originate in sites of lower temperature.