Cutaneous leishmaniasis in sub-Saharan Africa: a systematic review of Leishmania species, vectors and reservoirs

Abstract

Background: Cutaneous leishmaniasis (CL) is understudied in sub-Saharan Africa. The epidemiology of CL is determined by the species involved in its transmission. Our objectives were to systematically review available data on the species of Leishmania, along with vectors and reservoirs involved in the occurrence of human cases of CL in sub-Saharan Africa, and to discuss implications for case management and future research.

Methods: We systematically searched PubMed, Scopus, Cochrane and African Index Medicus. There was no restriction on language or date of publication. The review was conducted according to PRISMA guidelines and was registered on PROSPERO (CRD42022384157).

Results: In total, 188 published studies and 37 reports from the grey literature were included. An upward trend was observed, with 45.7% of studies published after 2010. East Africa (55.1%) represented a much greater number of publications than West Africa (33.3%). In East Africa, the identification of reservoirs for Leishmania tropica remains unclear. This species also represents a therapeutic challenge, as it is often resistant to meglumine antimoniate. In Sudan, the presence of hybrids between Leishmania donovani and strictly cutaneous species could lead to important epidemiological changes. In Ghana, the emergence of CL in the recent past could involve rare species belonging to the Leishmania subgenus Mundinia. The area of transmission of Leishmania major could expand beyond the Sahelian zone, with scattered reports in forested areas. While the L. major-Phlebotomus duboscqi-rodent complex may not be the only cycle in the dry areas of West Africa, the role of dogs as a potential reservoir for Leishmania species with cutaneous tropism in this subregion should be clarified. Meglumine antimoniate was the most frequently reported treatment, but physical methods and systemic agents such as ketoconazole and metronidazole were also used empirically to treat L. major infections.

Conclusions: Though the number of studies on the topic has increased recently, there is an important need for intersectional research to further decipher the Leishmania species involved in human cases of CL as well as the corresponding vectors and reservoirs, and environmental factors that impact transmission dynamics. The development of molecular biology in sub-Saharan Africa could help in leveraging diagnostic and research capacities and improving the management of human cases through personalized treatment strategies.

Keywords: Cutaneous leishmaniasis; One Health; Reservoirs; Review; Sub-Saharan Africa; Vectors.

Fig. 1

PRISMA 2020 flow diagram, systematic review of species of Leishmania, vectors and reservoirs involved in human cutaneous leishmaniasis in sub-Saharan Africa, 2023

Fig. 2

Map of the different sub-Saharan African countries with corresponding cases of Leishmania species reported in humans, 2023

Fig. 3

Sankey diagram showing the reported links for each species of Leishmania, and vector and reservoir involved in cutaneous leishmaniasis in sub-Saharan Africa; vectors are on the left of the diagram, reservoirs on the right; countries of isolation are in the center of the diagram; Leishmania species are indicated by different colours