Home » Volumes » Volume 50 November/December 2017 » Rhodnius stali: new vector infected by Trypanosoma rangeli (Kinetoplastida, Trypanosomatidae)

Rhodnius stali: new vector infected by Trypanosoma rangeli (Kinetoplastida, Trypanosomatidae)

Gabriela Vieira de Souza Castro1 Mariane Albuquerque Lima Ribeiro1 2 Leandro José Ramos2 3 Jader de Oliveira4 5 João Aristeu da Rosa4 5 Luis Marcelo Aranha Camargo1 2 3 5 6 Dionatas Ulises de Oliveira Meneguetti1 9 10

1Programa de Pós-Graduação Stricto Sensu em Ciência da Saúde na Amazônia Ocidental, Universidade Federal do Acre, Rio Branco, AC, Brasil. 2Centro de Ciências da Saúde e do Desporto, Universidade Federal do Acre, Rio Branco, AC, Brasil. 3Programa de Pós-Graduação Stricto Sensu em Biodiversidade e Biotecnologia da Amazônia Legal, Universidade Federal do Acre, Rio Branco, AC, Brasil. 4Departamento de Ciências Biológicas, Faculdade de Ciências Farmacêuticas, Universidade Estadual Paulista Júlio de Mesquita Filho, Araraquara, SP, Brasil. 5Programa de Pós-Graduação Stricto Sensu em Biociências e Biotecnologia, Universidade Estadual Paulista Júlio de Mesquita Filho, Araraquara, SP, Brasil. 6Instituto de Ciências Biomédicas-5, Universidade de São Paulo, Monte Negro, RN, Brasil. 7Departamento de Medicina, Faculdade São Lucas, Porto Velho, RN, Brasil. 8Centro de Pesquisas em Medicina Tropical, Porto Velho, RN, Brazil. 9Programa de Pós-Graduação Stricto Sensu em Ciência, Inovação e Tecnologia para a Amazônia, Universidade Federal do Acre, Rio Branco, AC, Brasil. 10Colégio de Aplicação, Universidade Federal do Acre, Rio Branco, AC, Brasil.

DOI: 10.1590/0037-8682-0054-2017

The encounter of R. stali infected by T. rangeli generates an alert for the state of Acre, since the simultaneous presence with Trypanosoma cruzi can make the differential diagnosis of Chagas disease difficult.



Rhodnius stali infection by Trypanosoma rangeli is reported in this study for the first time.


The triatomines were collected from the campus of the Federal University of Acre in Rio Branco, Acre, Brazil. The identification of T. rangeli was confirmed by multiplex polymerase chain reaction.


The examinations of two specimens revealed R. stali infection by the epimastigote forms of T. rangeli.


The encounter of R. stali infected by T. rangeli generates an alert for the state of Acre, since the simultaneous presence with Trypanosoma cruzi can make the differential diagnosis of Chagas disease difficult.

Keywords: Triatomines; Rangeliose; Trypanosomatids

The protozoan Trypanosoma rangeli is a hemoflagellate parasite, belonging to the family Trypanosomatidae, and it generally infects invertebrate hosts, such as hematophagous insects, and vertebrate hosts such as mammals, including humans. Its transmission occurs mainly during the blood feeding of some species of triatomines1.

Human infections such as those caused by parasites have been reported in Central and South America, including Brazil, where cases of human rangeliosis have been reported in the States of Amazonas, Pará, Alagoas, Minas Gerais, Santa Catarina, and Bahia2,3.

Although there have been no reports of adverse health effects caused by T. rangeli in vertebrates, this protozoan is considered to be pathogenic to invertebrates1.

It is recognized that the species of triatominae belonging to the genus Rhodnius are susceptible to infection by Trypanosoma rangeli, and the occurrence has already been recorded in the following species: Rhodnius domesticusRhodnius nasutusRhodnius neglectus4Rhodnius pallescensRhodnius prolixusRhodnius robustus5Rhodnius brethesi6Rhodnius colombiensisRhodnius ecuadoriensis7Rhodnius dalessandroiRhodnius pictipes8Rhodnius montenegrensis9, and Rhodnius neivai10. However, there are no records of T. rangeli infection in Rhodnius amazonicus, Rhodnius barretti, Rhodnius milesi, Rhodnius paraenses, and Rhodnius zeledoni, also considered to be possible vectors of this parasite8.

This study describes the first report of R. stali infected by T. rangeli. Two specimens of R. stali (Figure 1) were collected on the campus of the Federal University of Acre [Universidade Federal do Acre (UFAC)] in the City of Rio Branco, Acre, Brazil (Lat. 9º57´12’’S, Long. 65º’51´.48’’W) (Figure 2), probably attracted by the campus lighting. The triatomines were found in the vicinity of the Zoobotanical Park at the University, a location that contains several palm trees of the genus Attalea, which are considered to be natural ecotones for R. stali in the southwest region of the Amazon11. This locality also contains wild mammals such as bats, agoutis, and capybaras that circulate frequently in the dependences of the university.

FIGURE 1: Dorsal view of Rhodnius stali. 

FIGURE 2: Geographical location of the municipality of Rio Branco, State of Acre, Brazil. 

Identification of the triatomines was carried out in the Department of Biological Sciences of the Faculty of Pharmaceutical Sciences, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Araraquara, São Paulo, Brazil, via comparison between characteristics of R. stali genitalia and those of R. pictipes from the same insectarium (CTA 71), collected in Belém, Pará. These characteristics have been reported as being similar to those described by Lent et al.12,13.

Initially, fresh and stained smears were prepared with 0.1% triarylmethane, 0.1% xanthenes and 0.1% thiazines) from the contents of the triatomine rectal ampulla and were then analyzed under a 1,600X optical microscope (Figure 3A and B).

FIGURE 3: A and B: Epimastigote form of Trypanosoma rangeli at 1,600X magnification. 

The trypanosomatid species were confirmed by multiplex polymerase chain reaction (PCR). Parasite deoxyribonucleic acid (DNA) was extracted from the triatomine rectal samples using a Qiagen DNA extraction kit®. The multiplex PCR was performed according to a protocol described by Fernandes et al.14. This method amplifies a portion of the non-transcribed spacer of the mini-exon gene that varies between T. cruzi and T. rangeli species, and between lines 1 and 2 of T. cruzi. The following primers were used: TC1, 5’-ACACTTTCTGGCGCTGATCG-3’; TC2, 250 bp, 5’-TTGCTCGCACACTCGGCTGCAT-3’; Z3, 150 bp, 5’-CCGCGCACAACCCCTATAAAAATG-3’; TR, 100 bp, 5’-CCTATTGTGATCCCCATCTTCG-3’ and EXON, 5’-TACCAATATAGTACAGAACTG-3’. The reaction mixture consisted of 100pmol of each primer and 150μM deoxynucleotide triphosphates (dNTPs) in a buffer composed of 10mM Tris-HCl (pH 8.3), 1.5mM MgCl2, 25mM KCl, 0.1mg/mL bovine serum albumin, 2.5U of Taq DNA polymerase, and 10ng of genomic DNA in a total volume of 50μL. The thermal cycling conditions were as follows: an initial step of 5 min at 95°C, 34 cycles of 30 s at 94°C, 30 s at 55°C, and 30 s at 72°C, and a final extension of 10 min at 72°C. The following reference strains were used as controls in each reaction: TC1, X10 Clone 1; TC2, Strain Y; Z3, Emerald Clone 1, and T. rangeliR1625. The amplified products were subjected to electrophoresis on a 2% agarose gel at 100V for 1h. After electrophoresis, the DNA was stained with ethidium bromide and visualized under ultraviolet light. A molecular marker of 50 base pairs was used as a size control for the amplified fragments9.

This first report of R. stali infection by T. rangeli increases the total number of triatomine vector species of this protozoan from 13 to 14, with 8 of these occurring in Brazil. It is known that the protozoan T. rangeli can be found infecting any species of triatomine; however, the only vectors of this trypanosomatid confirmed to date are the species of the genus Rhodnius8. The report of a 14th species of Rhodnius infected by T. rangeli is important, since it is known that this protozoan has relevance for the study of Chagas disease, since more than 60% of its antigens are associated with T. cruzi1.

The occurrence of T. rangeli naturally infecting R. stali offers increased knowledge of the geographical distribution of this parasite in the northern region of Brazil, because it acts as an alert regarding epidemiological surveillance of the same area. Moreover, it is known that the occurrence of T. cruzi and T. rangeli in the same geographical region, allows for the occurrence of mixed infections in both vertebrate hosts and vectors1, making it difficult to isolate and differentially diagnose the infection, leading to misdiagnoses of Chagas disease15. This situation is of concern, especially in regions where other vector species of T. rangeli are reported, such as the state of Acre, where they occur in addition to R. stali, for example, the species R. pictipes, R. robustus and R. montenegrensis10,14.

Ethical considerations

The specimens were collected with permission from the Brazilian Institute of Environment and Renewable Natural Resources [Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA)], permanent license Nr. 52260-1.


1. Guhl F, Vallejo GA. Trypanosoma (Herpetosoma) rangeli Tejera 1920: an updated review. Mem Inst Oswaldo Cruz. 2003;98(4):435-42. [ Links ]

2. Coura JR, Fernandes O, Arboleda M, Barrett TV, Carrada N, Degrave W, et al. Human infection by Trypanosoma rangeli in the Brazilian Amazon. Trans R Soc Trop Med Hyg. 1996;90(3):278-9. [ Links ]

3. Sousa MA, Silva Fonseca T, Santos BN, Santos Pereira SM, Carvalhal C, Hasslocher Moreno AM. Trypanosoma rangeli Tejera, 1920, in chronic Chagas disease patients under ambulatory care at the Evandro Chagas Clinical Research Institute (IPEC-FIOCRUZ, Brazil). Parasitol Res. 2008;103(3):697-703. [ Links ]

4. Machado PE, Eger-Mangrich I, Rosa G, Koerich LB, Grisard EC, Steindel M. Differential susceptibility of triatominae of the genus Rhodnius to Trypanosoma rangeli strains from different geographical origins. Int J Parasitol. 2001;31(5-6):631-3. [ Links ]

5. Urrea DA, Guhl F, Herrera CP, Falla A, Carranza JC, Cuba-Cuba C, et al. Sequence analysis of the spliced-leader intergenic region (SL-IR) and random amplified polymorphic DNA (RAPD) of Trypanosoma rangeli strains isolated from Rhodnius ecuadoriensisR. colombiensisR. pallescens and R. prolixus suggests a degree of co-evolution between parasites and vectors. Acta Trop. 2011;120(1-2):59-66. [ Links ]

6. Maia da Silva F, Junqueira AC, Campaner M, Rodrigues AC, Crisante G, Ramírez LE, et al. Comparative phylogeography of Trypanosoma rangeli and Rhodnius (Hemiptera: Reduviidae) supports a long coexistence of parasite lineages and their sympatric vectors. Mol Ecol. 2007;16(16):3361-73. [ Links ]

7. Vallejo GA, Guhl F, Schaub GA. Triatominae-Trypanosoma cruzi/T. rangeli: vector-parasite interactions. Acta Trop . 2009;110(2-3):137-47. [ Links ]

8. Vallejo GA, Suárez Y, Olaya JL, Gutiérrez SA, Carranza JC. Trypanosoma rangeli: un protozoo infectivo y no patógeno para el humano que contribuye al entendimiento de latransmisión vectorial y la infección por Trypanosoma cruzi, agente causal de la enfermedad de Chagas. Rev Acad Colomb Cienc Ex Fis Nat. 2015;39(150):111-22. [ Links ]

9. Meneguetti DUO, Soares EB, Campaner M, Camargo LMA. First report of Rhodnius montenegrensis (Hemiptera: Reduviidae: Triatominae) infection by Trypanosoma rangeli. Rev Soc Bras Med Trop. 2014;47(3):374-6. [ Links ]

10. D’Alessandro A, Hincapié O. Rhodnius neivai: A new experimental vector of Trypanosoma rangeli. Am J Trop Med Hyg. 1986;35(3):512-4. [ Links ]

11. Abad-Franch F, Monteiro FA. Biogeography and evolution of Amazonian triatomines (Heteroptera: Reduviidae): implications for Chagas disease surveillance in humid forest ecoregions. Mem Inst Oswaldo Cruz . 2007;102(Suppl 1):57-70. [ Links ]

12. Lent H, Jurberg J, Galvão C. Rhodnius stali n. sp. afim de Rhodnius pictipes Stal, 1872 (Hemiptera, Reduviidae, Triatominae). Mem Inst Oswaldo Cruz . 1993;88(4):605-14. [ Links ]

13. Meneguetti DUO, Castro GVS, Castro MALR, Souza JL, Oliveira J, Rosa JA, et al. First report of Rhodnius stali(Hemiptera, Reduviidae, Triatominae) in the State of Acre and in the Brazilian Amazon. Rev Soc Bras Med Trop . 2016;49(3):365-8. [ Links ]

14. Fernandes O, Santos SS, Cupolillo E, Mendonça B, Derre R, Junqueira ACV, et al. A mini-exon multiplex polymerase chain reaction to distinguish the major groups of Trypanosoma cruzi and Trypanosoma rangeli in the Brazilian Amazon. Trans R Soc Trop Med Hyg . 2001;95(1):97-9. [ Links ]

15. Peterson JK, Graham AL, Elliott RJ, Dobson AP, Triana Chávez O. Trypanosoma cruzi-Trypanosoma rangeli co-infection ameliorates negative effects of single trypanosome infections in experimentally infected Rhodnius prolixus. Parasitology. 2016;143(9):1157-67. [ Links ]

Received: February 09, 2017; Accepted: August 24, 2017

Corresponding author: Dr. Dionatas Ulises de Oliveira Meneguetti. e-mail:dionatas@icbusp.org

Conflict of interest: The authors declare that there is no conflict of interest.