Trypanosoma rangeli

Synonyms: Trypanosoma guatemalense, T. ariarii.

T. rangeli was first found in the triatomid, Rhodnius prolixus, in Venezuela. It was later found in children in Guatemala and still later in Colombia, Chile and El Salvador. It is quite common in dogs, cats and man in certain areas of Venezuela, Colombia and Guatemala, and is sometimes found in mixed infections with T. cruzi. Groot, Renjifo and Uribe (1951) found it in 67 of 183 persons in the Ariari Valley and Groot (1951) found it in 1 of 30 persons, 2 of 27 dogs and an opossum in the Miraflores region of Colombia. It has also been found in the monkey, Cebus fatuellus. Young mice, rats and rhesus monkeys can be infected experimentally.

The trypanosomes in the blood are considerably larger than T. cruzi, being 26 to 36 u long. The nucleus is anterior to the middle of the body, the undulating membrane is rippled and the kinetoplast is small and subterminal.

The most common vector is Rhodnius prolixus, but Triatoma dimidiata and other triatomids have also been found infected. A piriform stage about 7 u long has been found in the foregut, and crithidial and metacyclic trypanosome forms develop in the hindgut. The crithidial stages may be extremely long, ranging from 32 to 70 or even over 100 u in length. The metacyclic trypanosome forms have a well-developed undulating membrane and a long free flagellum. They may pass into the hemolymph and thence to the salivary glands. They can be transmitted either by bite or by fecal contamination.

T. rangeli does not appear to be pathogenic for vertebrates, but Grewal (1957) found that it was pathogenic for R. prolixus and also for experimentally infected bedbugs.

The blood forms of T. rangeli can be readily differentiated from those of T. cruzi by their larger size and their much smaller kinetoplast. The forms in the insect hosts can be distinguished by their small kinetoplast and giant crithidial forms.

T. rangeli can be easily cultivated in a modified NNN medium containing glucose, peptone and macerated meat (Pifano, 1948). The culture forms are similar to those in the triatomid intestine. For further information regarding this species, see Groot, Renjifo and Uribe (1951), Groot (1954), Pifano (1948, 1954) and Zeledon (1954).