Trypanosoma rangeli Tejera, 1920
ETYMOLOGY: This parasite is named after Dr. Rangel.
SYNONYMS:Trypanosoma escomeli Yorke, 1920; Trypanosoma guatamalense De Léon, 1946; Trypanosoma cebus Floch and Abonnenc, 1949; Trypanosoma ariarii Groot, Renjifo, and Uribe, 1951.
HISTORY: This trypanosome like Trypanosoma cruzi was first discovered in its invertebrate vector Tejera (1920). Although nonpathogenic trypanosomes were observed in Latin America after this time, it was some time until the nonpathogenic trypanosomes isolated from the human blood were identified as T. rangeli (Piafano, Mayer, Medina, and Pinto, 1948).
GEOGRAPHIC DISTRIBUTION: This organism is found in Central America and South America down into Chile.
LOCATION IN THE HOST: In the mammalian host, the trypomastigote stage of the parasite is found within the peripheral blood.
DIAGNOSIS: Trypomastigotes may be identified within a peripheral blood smear, as like T. cruzi, may be better identified above the buffy coat in a hematocrit tube viewed under 400X magnification. Culture may be attempted in axenic media. Trypanosoma rangeli may be distinguished from T. cruzi morphologically, and with mouse infection studies: T. rangeli does not infect mice.
IDENTIFICATION OF THE PARASITE: The trypomastigote stage of Trypanosoma rangeli is the only stage of the parasite found in the vertebrate host. The trypomastigote may be seen to be dividing. The trypomastigote is slender, 26 to 34 m long; the undulating membrane is well developed and may have 4 to 5 undulations throughout its length. The kinetoplast is small and subterminal to the posterior end of the cell. The free flagellum of Trypanosoma rangeli that extends from the anterior end is about one-half to two-thirds of the length of the cell body.
LIFE CYCLE: This parasite is transmitted between hosts by the bite of triatomid bugs (Groot, 1952); genera that have been shown to serve as vectors include Rhodnius and Triatoma. Within bugs that have ingested blood containing trypomastigotes, the parasites develop within the hemolymph and then make their way to the salivary glands. In the vertebrate host, the parasites multiply within the blood stream.
CLINICAL PRESENTATION AND PATHOGENESIS: This trypanosome is apparently nonpathogenic in humans, and it would likely be nonpathogenic in cats.
TREATMENT: There are no reports of attempted treatment of infected cats.
EPIZOOTIOLOGY: Overall, very few cats have been examined for the presence of Trypanosoma rangeli. A cat in Venezuela was found to have circulating trypomastigotes of Trypanosoma rangeli in its blood (Pifano, 1954). More recently, 8.5% of cats in Venezuela were shown to be infected with Trypanosoma rangeli (Tonn et al., 1983).
HAZARDS TO OTHER ANIMALS: Although transmission to other animals could occur, this protozoan is considered to be nonpathogenic.
HAZARDS TO HUMANS: The role of cats in the epidemiology of this nonpathogenic organism is not known.
CONTROL/PREVENTION: Control and prevention of the disease in cats would, in part, be similar to that for humans, i.e., removing the domesticated triatomid vectors from the living quarters. However, the nature of cats to hunt on their own in the wilds will continue to place them at risk of acquiring infections from this parasite.
Groot H. 1952. Further observations on Trypanosomaariarii of COlombia, South America. Am J Trop Med Hyg 1:585-592.
Pifano F, Mayer M, Medina R , Pinto HB. 1948. Primera comprabación de Trypanosomarangeli en el organisms humana por cultiva sangria perifica. Arch Venezol Patol Trop Parasitol 1:1-31.
Pifano F. 1954. Nueva trypanosomiasis humana de la region neotropica producida por el Trypanosomarangeli, con especial referencia a Venezuela. Arch Venezol Patol Trop Parasitol 2:89-120.
Tejera E. 1920. Un nouveau flagellé de Rhodniusprolixus, Trypanosoma (ou Crithidia) rangeli n.sp. Bull soc Path Exot 13:525-530.
Tonn RJ, Cedillos RA, Ortegon A, Gonzalez JJ, Carrasquero B. 1983. Reservorios domésticos de Trypanosomacruzi y Trypanosomarangeli en Venezuela. Bol Dir Malariol Saneam Ambient 23:18-26.