Genetic diversity and population structure of Glossina morsitans morsitans in the active foci of human African trypanosomiasis in Zambia and Malawi.

Yukiko Nakamura,Cornelius Mweempwa,John Chisi,Noboru Inoue,Kalinga Chilongo,Naoki Osada,Chihiro Sugimoto,Junya Yamagishi,Janelisa Musaya,Boniface Namangala,Kyoko Hayashida,Elisha Chatanga,Brian L Weiss

doi:10.1371/journal.pntd.0007568

Abstract

The tsetse fly, Glossina morsitans morsitans, is a significant problem in Zambia and Malawi. It is the vector for the human infective parasite Trypanosoma brucei rhodesiense, which causes human African trypanosomiasis, and various Trypanosoma species, which cause African animal trypanosomiasis. Understanding the genetic diversity and population structure of G. m. morsitans is the basis of elucidating the connectivity of the tsetse fly populations, information that is essential in implementing successful tsetse fly control activities. This study conducted a population genetic study using partial mitochondrial cytochrome oxidase gene 1 (CO1) and 10 microsatellite loci to investigate the genetic diversity and population structure of G. m. morsitans captured in the major HAT foci in Zambia and Malawi. We have included 108 and 99 G. m. morsitans samples for CO1 and microsatellite analyses respectively. Our results suggest the presence of two different genetic clusters of G. m. morsitans, existing East and West of the escarpment of the Great Rift Valley. We have also revealed genetic similarity between the G. m. morsitans in Kasungu National Park and those in the Luangwa river basin in Zambia, indicating that this population should also be included in this historical tsetse belt. Although further investigation is necessary to illustrate the whole picture in East and Southern Africa, this study has extended our knowledge of the population structure of G. m. morsitans in Southern Africa.

Highlights

Tsetse flies (Glossina spp.) are the vector for the Trypanosoma parasites that cause human African trypanosomiasis (HAT) and African animal trypanosomiasis (AAT)
Analysis of the 407-bp fragment of the cytochrome oxidase gene 1 (CO1) gene of 108 individual G. m. morsitans flies from five locations resulted in the identification of 16 haplotypes, Hap_1 to Hap_16 (Fig 2, Table 1)
We analyzed partial mitochondrial CO1 sequences and 10 microsatellite loci of G. m. morsitans collected from three locations of Zambia and two locations from Malawi, and identified two genetically separated clusters: NWR and others

Summary

Introduction

Tsetse flies (Glossina spp.) are the vector for the Trypanosoma parasites that cause human African trypanosomiasis (HAT) and African animal trypanosomiasis (AAT). Both diseases present a significant burden in terms of public health and economy in sub-Saharan Africa [1,2]. Control of both diseases are difficult, mainly due to the presence of wild and domestic animal reservoirs, the lack of prophylactic drugs and vaccines, and the high cost and severe side effects of available drugs. Several population genetics studies have been successful in identifying population structure and the extent to which the discrete populations are connected by dispersal and migration in several tsetse-infested African countries [5,6,7,8]

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