A Clinical Study to Develop a Controlled Human Infection Model Using Leishmania Major-infected Sand Flies

Plain-language summary

The disease leishmaniasis mainly occurs in hot and tropical countries, affects millions of people and causes around 20,000 deaths across the world every year. Leishmaniasis is caused by the Leishmania parasite and is transmitted by sand flies. The parasite is tiny and not visible to the naked eye, whereas the sand fly is visible but small and inconspicuous. There are different types of leishmaniasis which can affect the skin (cutaneous leishmaniasis) or the internal organs of the body (visceral leishmaniasis). Some of the milder forms will produce skin problems which will be localised, whilst other forms of leishmaniasis will cause widespread skin changes. The skin lesions of cutaneous leishmaniasis can be disfiguring if left untreated. There are some treatments for leishmaniasis but many of them are not easy to use or don't work well. Therefore, new treatments are needed including vaccines that prevent or work against leishmaniasis. A solution being adopted for other diseases, which the investigators now wish to adopt for leishmaniasis is to develop a 'Controlled human infection model' (CHIM). These models involve deliberate exposure of individuals to an infection, in order to better understand how the disease works and to test potential vaccines and treatments. They have contributed knowledge that has led to advances in the development of treatments. This is study builds on an our initial successful study, FLYBITE, where uninfected (disease-free) sand flies were used to test the safety aspects and ensure that sand flies were able to bite human participants in a controlled environment. The investigators observed no major adverse effects and it was well tolerated by participants. The investigators therefore wish to proceed to a study using sand flies infected with a form of leishmaniasis that causes localised skin disease and is treatable, on the pathway to assessing future vaccines.

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