Trypanosoma acomys (Wenyon, 1909): reproductive forms and course of parasitemia in the natural hostAcomys cahirinus (Desmarest, 1819)

Abstract

Trypanosoma acomys (Stercoraria, Trypanosomatidae) was studied in the laboratory-bred spiny mouseAcomys cahirinus. Only trypomastigotes were found in peripheral blood, whereas the thymus of experimentally infectedA. cahirinus showed amastigote syncytial reproductive forms whose number of nuclei ranged from 2 to 128. These reproductive forms were detected 9–10 days after the i.p. injection of spiny mice with trypanosomes obtained from primary lung cultures. Transitional trypomastigote-like forms were observed in the thymus; no reproductive or dividing forms were encountered in any other tissue, including blood. The course of the parasitemia in spiny mice inoculated i.p. with 1.2×10⁶ parasites from 26- to 32-day-old cultures initiated from infected lungs was studied. A similar, characteristic pattern was observed in both male and female hosts. Four phases were recognized: latent, logarithmic, stationary, and decline. These phases ended on days 2, 14, 98, and 154 postinoculation, respectively. The decline phase was gradual and the parasites could not be detected by day 154 postinoculation. In contrast, inoculation from older cultures (35–50 days old) showed longer latent and logarithmic phases, a shorter stationary phase, and a sharp drop in parasite density during the decline phase; the parasites were not detected in the peripheral blood by 120 days postinoculation.