Abstract
BackgroundCutaneous 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.MethodsA 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.ResultsGenetic 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.ConclusionThe 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.
Highlights
Cutaneous Leishmaniasis (CL) is endemic in Sudan
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 parasites within the Leishmania donovani complex usually invade the macrophages of the liver, spleen and bone marrow causing the severe symptoms of the fatal Visceral Leishmaniasis (VL) [3,4]; while the parasites of L. major complex which cause Cutaneous Leishmaniasis (CL) invade the subcutaneous reticulo-endothelial system and cause self-healing lesions that leave life-long scars [5,6]
Summary
Cutaneous Leishmaniasis (CL) is endemic in Sudan It is caused by Leishmania major parasites and transmitted by Phlebotomus papatasi sandflies. Phlebotomus papatasi (Scopoli, 1786) is the principal vector of Leishmania major in the Old World [1] It is a widely distributed species found in variable habitats and associated with a wide range of vertebrate hosts [7,8]. Due to their poor dispersal capacity, populations of P. papatasi are expected to show some genetic structuring along their geographical range as a result of adaptation to local habitats and limited gene flow [9] Such genetic variability could play an important role in the epidemiology and clinical manifestations of leishmaniasis since it affects the vectorial capacity of the vector [10,11]
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