Leishmania infection in sand flies in a Cutaneous Leishmaniasis focus in Ghana

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JUNE 2015
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Abstract
Leishmaniasis is a parasitic disease caused by various species of the genus Leishmania, a protozoan parasite transmitted through the bite of an infected female Phlebotomine sand fly. There are three forms of the disease namely, visceral leishmaniasis, cutaneous leishmaniasis and muco-cutaneous leishmaniasis. Cutaneous leishmaniasis is the most common form of leishmaniasis, characterized by sores on the skin that usually enlarge with time and develop into an ulcer. The disease is caused by various Leishmania sp. and depending on whether human beings are the main reservoir or other small mammals, transmission is usually considered anthroponothic or zoonotic. The distribution of leishmania infection in sand flies was examined in some endemic cutaneous leishmaniasis (CL) communities of the Volta Region, Ghana. CL was first reported in 1999 in these communities by the Ghana Health Service in the Ho, Hohoe and kpando municipality. Since the first outbreak of the disease, there have been increasing reports of the disease in various villages in the Volta Region of Ghana. The present study therefore, conducted to identify natural infection by Leishmania sp. in insect vectors of CL. Entomological survey was conducted in three endemic communities (Dodome Awuiasu, Dodome Dogblome and Lume Atsiame) in the Volta Region. From October 2012 to February 2013, a total of 4219 female sand flies were captured with Center for Disease Control (CDC) light traps and dissected for studies on the head and last three abdominal segments for identification. It was observed that twenty (0.5%) female sandflies were identified from the genus Phlebotomus and 4199 (99.5%) belong to Sergentomyia. To determine leismania infection in female sandlies, DNA was extracted from pools of sand fly species ranging from 1 to 25 dissected females. This was done using a Qiagen DNA extraction Kit. In considering the pools of individual sandfly species, Leishmania sp. infection of 0.0384% (95% CI, 0.00119-0.197) was vi detected in a pool of 7 (5.7%). S. africana female sand flies out of 122 pools using PCR. The infection was detected in sand flies collected from Dodome Dogblome. This is the first report of natural infection by Leishmania sp. in S. africana in Ghana. This observation that S. africana is naturally infected by Leishmania sp., suggested that the sand fly species might play a role in the transmission of cutaneous Leishmaniasis in that part of the Volta Region of Ghana. The control of Leishmaniasis in endemic areas requires understanding of Leishmania ecology and the epidemiology of the disease. Finding naturally infected sand flies is important in identifying species of sand flies as a vector(s) of Leishmania in studying infection rates and estimating the prevalence of the disease in endemic communities that experience occasional outbreaks of Cutaneous Leishmaniasis.
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A Thesis submitted to the Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Master of Philosophy in Entomology.
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