Genetic diversity of trypanosome species in tsetse flies (Glossina spp.) in Nigeria

Judith Sophie Weber,Thaddeus Terlumun Gbem,Sørge Kelm,Jonathan Andrew Nok,Daniel Mbunkah Achukwi,Mohammed Mamman,Gloria Dada Chechet,Stephen Saikiu Shaida,Sen Claudine Henriette Ngomtcho

doi:10.1186/s13071-019-3718-y

Abstract

BackgroundTrypanosomes cause disease in humans and livestock in sub-Saharan Africa and rely on tsetse flies as their main insect vector. Nigeria is the most populous country in Africa; however, only limited information about the occurrence and diversity of trypanosomes circulating in the country is available.MethodsTsetse flies were collected from five different locations in or adjacent to protected areas, i.e. national parks and game reserves, in Nigeria. Proboscis and gut samples were analysed for trypanosome DNA by molecular amplification of the internal transcribed spacer 1 (ITS1) region and part of the trypanosome specific glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene.ResultsThe most abundant Trypanosoma species found in the tsetse gut was T. grayi, a trypanosome infecting crocodiles. It was ubiquitously distributed throughout the country, accounting for over 90% of all cases involving trypanosomes. Trypanosoma congolense was detected in gut samples from all locations except Cross River National Park, but not in the proboscis, while T. brucei (sensu lato) was not detected at all. In proboscis samples, T. vivax was the most prominent. The sequence diversity of gGAPDH suggests that T. vivax and T. grayi represent genetically diverse species clusters. This implies that they are highly dynamic populations.ConclusionsThe prevalence of animal pathogenic trypanosomes throughout Nigeria emphasises the role of protected areas as reservoirs for livestock trypanosomes. The genetic diversity observed within T. vivax and T. grayi populations might be an indication for changing pathogenicity or host range and the origin and consequences of this diversity has to be further investigated.

Highlights

Trypanosomes cause disease in humans and livestock in sub-Saharan Africa and rely on tsetse flies as their main insect vector
Distribution of T. grayi and other Trypanosoma species in Nigeria Evidence for trypanosomal DNA was obtained by amplification of the internal transcribed spacer 1 (ITS1) region of Kinetoplastida in 42% of the 413 analysed gut samples and 18.7% of the 412 proboscis samples (Tables 2, 3)
This study provides an overview of trypanosome species in the gut and proboscis of tsetse from different regions in Nigeria, with a focus on protected areas (GR and national parks (NP))

Summary

Introduction

Trypanosomes cause disease in humans and livestock in sub-Saharan Africa and rely on tsetse flies as their main insect vector. African trypanosomes are protozoan parasites causing disease in humans and livestock in sub-Saharan Africa. The trypanosomes of greatest socioeconomic importance are Trypanosoma brucei (sensu lato), T. congolense and T. vivax. They rely largely on the presence of tsetse flies (Glossina sp.) as their key biological vector, whose geographical distribution is restricted to sub-Saharan Africa. The Salivaria are transmitted via the saliva and mouthparts of the infected vector and consist of the African trypanosomes Trypanosoma brucei (s.l.), T. congolense, T. simiae, T. godfreyi, T. suis and T. vivax. Rhodesiense cause the severe disease human African trypanosomiasis (HAT; sleeping sickness). Trypanosoma congolense, T. vivax and the third subspecies of T. brucei (s.l.), T. b. brucei, cause African animal trypanosomiasis (AAT; nagana) mainly in cattle and other livestock [4]

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