First Molecular Epidemiological Study of Cutaneous Leishmaniasis in Libya

Cutaneous leishmaniasis (CL) is caused by protozoan parasites of the genus Leishmania. The disease is characterized by the formation of chronic skin lesions followed by permanent scars and deformation of the infected area. It is distributed in many tropical and subtropical countries with more than 2 million cases every year. During the past few years CL has emerged as a major public health problem in Libya. So far, diagnosis was based on clinical symptoms and microscopic observation of parasites. Disease outbreaks were not investigated and the causative leishmanial species of CL were not identified so far. Our study indicates the presence of two coexisting species: Leishmania major and Leishmania tropica. These results are crucial in order to provide accurate treatment, precise prognosis and appropriate public health control measures. The recent armed conflict in Libya that ended with the Gadhafi regime collapse on October 2011 has affected all aspects of the life in the country. In this study we discussed multiple risk factors that could be associated with this conflict and present major challenges that should be considered by local and national health authorities for evaluating the CL burden and highlighting priority actions for disease control

Temporal Dynamics and Impact of Climate Factors on the Incidence of Zoonotic Cutaneous Leishmaniasis in Central Tunisia

Old world cutaneous leishmaniasis is a vector-borne disease occurring in rural areas of developing countries. The main reservoirs are the rodents Psammomys obesus and Meriones shawi. Zoonotic Leishmania transmission cycle is maintained in the burrows of rodents where the sand fly Phlebotomus papatasi finds the ideal environment and source of blood meals. In the present study we showed seasonality of the incidence of disease during the same cycle with an inter-epidemic period ranging from 4 to 7 years. We evaluated the impact of climate variables (rainfall, humidity and temperature) on the incidence of zoonotic cutaneous leishmaniais in central Tunisia. We confirmed that the risk of disease is mainly influenced by the humidity related to the months of July to September during the same season and mean rainfall lagged by 12 to 14 months

Spatio-temporalgenetic structuring of Leishmania major in Tunisia by microsatellite analysis

In Tunisia, cases of zoonotic cutaneous leishmaniasis caused by Leishmania major are increasing and spreading from the south-west to new areas in the center. To improve the current knowledge on L. major evolution and population dynamics, we performed multi-locus microsatellite typing of human isolates from Tunisian governorates where the disease is endemic (Gafsa, Kairouan and Sidi Bouzid governorates) and collected during two periods: 1991-1992 and 2008-2012. Analysis (F-statistics and Bayesian model-based approach) of the genotyping results of isolates collected in Sidi Bouzid in 1991-1992 and 2008-2012 shows that, over two decades, in the same area, Leishmania parasites evolved by generating genetically differentiated populations. The genetic patterns of 2008-2012 isolates from the three governorates indicate that L. major populations did not spread gradually from the south to the center of Tunisia, according to a geographical gradient, suggesting that human activities might be the source of the disease expansion. The genotype analysis also suggests previous (Bayesian model-based approach) and current (F-statistics) flows of genotypes between governorates and districts. Human activities as well as reservoir dynamics and the effects of environmental changes could explain how the disease progresses. This study provides new insights into the evolution and spread of L. major in Tunisia that might improve our understanding of the parasite flow between geographically and temporally distinct populations

No evidence of interspecific genetic exchange by multi-locus microsatellite typing between Leishmania killicki and Leishmania major in a mixed focus of cutaneous Leishmaniasis in Southeast Tunisia

Sixty-four Leishmania samples were isolated from patients in several villages in the Tataouine governorate, southeast Tunisia. This region is known to be a mixed focus of human cutaneous Leishmaniasis caused by Leishmania (L.) killicki (synonymous L. tropica) and L. major. To identify the Leishmania species in this governorate, a nested polymerase chain reaction based on the variable region of the kinetoplast minicircle was performed on each isolate. Multi-locus microsatellite typing using markers selected for their ability to amplify the two species was used to explore patterns of interspecific genetic exchange. Thirteen L. major and 51 L. killicki isolates were identified. The analysis of microsatellite data showed very low genetic diversity in each species with this set of microsatellites but a high differentiation between the two species. Nine L. major and five L. killicki strains revealed heterozygous genotypes with no shared allele between the two species. These heterozygotes probably resulted from genetic mutation events and not from interspecific genetic exchange. Specific and different epidemiological cycles at the sympatric level might explain the absence of genetic exchange between the two Leishmania species in the Tataouine governorate

Phleboviruses associated with sand flies in arid bio-geographical areas of Central Tunisia

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