A Stroll Through the History of Monoxenous Trypanosomatids Infection in Vertebrate Hosts.

Carolina Boucinha,André Luis Souza Dos Santos,Eduardo Caio Torres-Santos,Marta Helena Branquinha,Vítor Ennes-Vidal,Claudia Masini D’Avila-Levy,Valter Viana Andrade-Neto

doi:10.3389/fcimb.2022.804707

Abstract

The Trypanosomatidae family encompasses unicellular flagellates and obligate parasites of invertebrates, vertebrates, and plants. Trypanosomatids are traditionally divided into heteroxenous, characterized by the alternation of the life cycle between an insect vector and a plant or a vertebrate host, including humans being responsible for severe diseases; and monoxenous, which are presumably unique parasites of invertebrate hosts. Interestingly, studies reporting the occurrence of these monoxenous trypanosomatids in humans have been gradually increasing, either associated with Leishmania co-infection, or supposedly alone either in immunocompromised or even more sporadically in immunocompetent hosts. This review summarizes the first reports that raised the hypothesis that monoxenous trypanosomatids could be found in vertebrate hosts till the most current reports on the occurrence of Crithidia spp. alone in immunocompetent human patients.

Highlights

The family Trypanosomatidae encompasses eukaryotic flagellates, unicellular and obligatory parasites of invertebrates, vertebrates, and plants
This review summarizes the first reports that raised the hypothesis that monoxenous trypanosomatids could be found in vertebrate hosts till the most current reports on the occurrence of Crithidia spp. alone in immunocompetent human patients
The heteroxenous trypanosomatids are the causative agents of severe human diseases that are mainly transmitted by an insect vector, such as Chagas disease, sleeping sickness, and the various forms of cutaneous and visceral leishmaniasis (Vickerman, 1994)

Summary

INTRODUCTION

The family Trypanosomatidae encompasses eukaryotic flagellates, unicellular and obligatory parasites of invertebrates, vertebrates, and plants. Trypanosomatids are traditionally divided into heteroxenous, characterized by alternating the life cycle between an insect vector and a vertebrate host or a plant; and monoxenous, which are parasites presumably exclusive of invertebrate hosts, mainly insects. Species typically non-pathogenic to humans are important models for understanding the biological behavior, biochemistry and molecular biology of pathogenic trypanosomatids (d’Avila-Levy et al, 2015). These organisms are being explored as vaccine candidates; for example, Phytomonas serpens confers protective immunity against T. cruzi (Pinge-Filho et al, 2005; da Silva et al, 2013); and as a platform to produce folded eukaryotic proteins, such as erythropoietin and insulin produced by Leishmania tarentolae (Dortay and MuellerRoeber, 2010). We will present a historical review since the first reports that raised the hypothesis that monoxenous trypanosomatids could be found in vertebrate hosts till the recent reports on the occurrence of Crithidia spp. in immunocompetent human patients

FIRST REPORTS ON THE OCCURRENCE OF MONOXENIC TRYPANOSOMATIDS IN HUMANS

CRITHIDIA OCCURRENCE IN IMMUNOCOMPETENT PATIENTS

Findings

FINAL CONSIDERATIONS