Double development cycle of Trypanosoma cruzi in the opossum.

Abstract

cance. T. cruzi was found to grow abundantly as eprmtilgotes and to transform Into trypomastrgotes Identical to metacyclic forms, in the lumen of the anal glands of a high proportion of laboratory reared opossums (Didelphis marsupialis) that had been subcutaneously inoculated with faeces of infected trratomine bugs. No intracellular amastlgotes were found In the various layers of the gland wall, not even in the thick striated muscular layer. The developmental phases in the lumen of the anal glands appear to mimic the parasite’s developmental cycle In the intestinal tract of the insect vectors (Figs I and 2). At the same time, a classic intracellular cycle, with trypomastigotes In the bloodstream, was shown by patent parasltaemia, positive haemoculture and xenodiagnosls, and by findtng amastrgotes tn myofibres of several muscles. All the opossums were positive in indirect fluorescent antibody tests. Parasites taken directly from the anal glands were cultivated in axenic media, Infected triatomine bugs, mice and opossums, and were typed to the same schizodeme and zymodeme of those derived from the blood and those of the inoculated strain. No doubt the population that developed In the lumen of the anal glands was part of