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Open Access Research

Evidence for genetic differentiation at the microgeographic scale in Phlebotomus papatasi populations from Sudan

Noteila M Khalid1*, Marium A Aboud2, Fathi M Alrabba3, Dia-Eldin A Elnaiem4 and Frederic Tripet5

Author Affiliations

1 Department of Zoology, Khartoum College of Medical Science, PO Box 10995, Khartoum, Sudan

2 Department of Biological Sciences, Faculty of Science, Al-Neelain University, Khartoum, Sudan

3 Department of Zoology, Faculty of Science, University of Khartoum, PO Box 321, Khartoum, Sudan

4 Department of Natural Sciences, University of Maryland Eastern Shore, Princess Anne, MD, USA

5 Centre for Applied Entomology and Parasitology, Keele University, Keele, Staffordshire, ST5 5BG, UK

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Parasites & Vectors 2012, 5:249  doi:10.1186/1756-3305-5-249

Published: 12 November 2012

Abstract

Background

Cutaneous Leishmaniasis (CL) is endemic in Sudan. It is caused by Leishmania major parasites and transmitted by Phlebotomus papatasi sandflies. Recently, uncommon clinical manifestations of CL have been reported. Moreover, L. donovani parasites that cause Visceral Leishmaniasis (VL) have been isolated from CL lesions of some patients who contracted the disease in Khartoum State, Central Sudan with no history of travelling to VL endemic sites on south-eastern Sudan. Because different clinical manifestations and the parasite behaviour could be related to genetic differentiation, or even sub-structuring within sandfly vector populations, a population genetic study was conducted on P. papatasi populations collected from different localities in Khartoum State known for their uncommon CL cases and characterized by contrasting environmental conditions.

Methods

A set of seven microsatellite loci was used to investigate the population structure of P. papatasi samples collected from different localities in Khartoum State, Central Sudan. Populations from Kassala State, Eastern Sudan and Egypt were also included in the analyses as outgroups. The level of genetic diversity and genetic differentiation among natural populations of P. papatasi was determined using FST statistics and Bayesian assignments.

Results

Genetic analyses revealed significant genetic differentiation (FST) between the Sudanese and the Egyptian populations. Within the Sudanese P. papatasi populations, one population from Gerif West, Khartoum State, exhibited significant genetic differentiation from all other populations including those collected as near as 22 km.

Conclusion

The significant genetic differentiation of Gerif West P. papatasi population from other Sudanese populations may have important implication for the epidemiology of leishmaniasis in Khartoum State and needs to be further investigated. Primarily, it could be linked to the unique location of Gerif West which is confined by the River Nile and its tributaries that may act as a natural barrier for gene flow between this site and the other rural sites. The observed high migration rates and lack of genetic differentiation among the other P. papatasi populations could be attributed to the continuous human and cattle movement between these localities.

Keywords:
Phlebotomus papatasi; Sudan; Gene flow; Genetic differentiation