Experimental Infection of Rhodnius prolixus (Hemiptera, Triatominae) with Mycobacterium leprae Indicates Potential for Leprosy Transmission

PLoS One. 2016 May 20;11(5):e0156037. doi: 10.1371/journal.pone.0156037. eCollection 2016.

Abstract

Leprosy is a chronic dermato-neurological disease caused by infection with Mycobacterium leprae. In 2013 almost 200,000 new cases of leprosy were detected around the world. Since the first symptoms take from years to decades to appear, the total number of asymptomatic patients is impossible to predict. Although leprosy is one of the oldest records of human disease, the mechanisms involved with its transmission and epidemiology are still not completely understood. In the present work, we experimentally investigated the hypothesis that the mosquitoes Aedes aegypti and Culex quinquefasciatus and the hemiptera Rhodnius prolixus act as leprosy vectors. By means of real-time PCR quantification of M. leprae 16SrRNA, we found that M. leprae remained viable inside the digestive tract of Rhodnius prolixus for 20 days after oral infection. In contrast, in the gut of both mosquito species tested, we were not able to detect M. leprae RNA after a similar period of time. Inside the kissing bug Rhodnius prolixus digestive tract, M. leprae was initially restricted to the anterior midgut, but gradually moved towards the hindgut, in a time course reminiscent of the life cycle of Trypanosoma cruzi, a well-known pathogen transmitted by this insect. The maintenance of M. leprae infectivity inside the digestive tract of this kissing bug is further supported by successful mice footpad inoculation with feces collected 20 days after infection. We conclude that Rhodnius prolixus defecate infective M. leprae, justifying the evaluation of the presence of M. leprae among sylvatic and domestic kissing bugs in countries endemic for leprosy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Feces / microbiology
  • Humans
  • Leprosy / genetics
  • Leprosy / microbiology*
  • Leprosy / transmission*
  • Microscopy, Fluorescence
  • Mycobacterium leprae / pathogenicity*
  • RNA, Ribosomal, 16S / genetics
  • Real-Time Polymerase Chain Reaction
  • Rhodnius / microbiology*

Substances

  • RNA, Ribosomal, 16S

Grants and funding

This work was supported by Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (www.faperj.br) and the Programa Institucional de Bolsas de Iniciação Científica PIBIC, from Oswaldo Cruz Foundation(www.pibic.fiocruz.br). The sources of funds had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.