Key words: Endotrypanum -Protozoa -Kinetoplastida -Trypanosomatidae -molecular taxonomy -enzyme activities -monoclonal antibodies -enzyme electrophoresis -DNA analyses -mammalian reservoirssandflies vectorsBiological characteristics of Endotrypanum spp. -Parasitic protozoa of the genus Endotrypanum are unique among the Kinetoplastida in that they infect erythrocytes of their mammalian host. Infection with Endotrypanum appears to be restricted to edentates, principally of forest-dwelling two-toed sloths of the genus Choloepus, but rarer infections with these flagellates seems to occur in three-toed sloths (genus Bradypus) (Fig. 1). As shown in Fig. 2, inside the erythocyte the Endotrypanum assumes an epimastigote or trypomastigote form, while in the sandfly or during in vitro culture the parasite assumes promastigote morphology (Shaw 1992). However, the complete life cycle of Endotrypanum spp. has not been reproduced in experimental studies. Other developmental stages of the parasite may occur within the mammalian host (Deane 1961).In nature, Endotrypanum parasites are probably transmitted by the bite of infected phlebotomine sandflies (Diptera: Psychodidae). Arias et al. (Rogers et al. 1988). Further evidence for the development of Endotrypanum in phlebotomines was obtained by feeding several laboratory-reared sandfly species on infected sloths (Shaw 1964, 1969, 1981, Christensen & Herrer 1977, 1979. In these studies, infections developing within the insect gut (Shaw 1964(Shaw , 1969 were similar to those found in wild caught sandflies (Johnson et al. 1963, Arias et al. 1985. Moreover, we have reported (Franco et al. 1997b) the developmental biology of Brazilian strains of Endotrypanum for three sandfly species. Development of Endotrypanum varied for each parasitehost species association. After feeding on culture forms of E. schaudinni, significantly more Lu. shannoni (100%, 9/9) became infected than did Lu. longipalpis (62.3%, 33/53) or Phlebotomus papatasi (27.3%, 15/55). The greatest number of infections were in the midgut and hindgut from 6 to 16 days after feeding, but flagellates also were present in the Malpighian tubules. Moreover, distinct development patterns in the sandfly gut were obtained when the Callejon Lu. longipalpis colony was fed on cultures of other Endotrypanum strains.
