Matoke-Muhia, Damaris and Owino, Barrack and Kiplagat, Stephen and Mwangi, Hannah N. and Ingonga, Johnstone M. and Njenga, Daniel and Septer, Benny and Kitondo, Mwatela and Mwiti, Daniel and Magiri, Charles and Nyakundi, Hellen and Onditi, Juliet Akoth and Weihl, Sarah and Wenger, Catherine and Wamai, Richard and Satoskar, Abhay R. and Villinger, Jandouwe and Kamhawi, Shaden and Ndungu, Joseph and Masiga, Daniel,2025-05-142025Available at SSRN: https://ssrn.com/abstract=5242611 or http://dx.doi.org/10.2139/ssrn.5242611https://repository.nrf.go.ke/handle/123456789/1399Background: Leishmaniasis is of major global health concern with global elimination targets set for 2030. East Africa accounts for ~75% of global visceral leishmaniasis (VL) cases. Hence, attention to endemic, recurrent or emerging foci is critical to meeting global elimination targets. In 2021, Kajiado County, on the southern border of Kenya with Tanzania, emerged with cases of local transmission that necessitated this investigation. Methods: This was a mixed methods coordinated response. We conducted a training for clinicians, sensitised communities, and set up medical camps in four villages. Here we screened the community for VL and other common ailments and undertook an entomological survey for sandfly vector species in the same villages. We screened 100 individuals (males: 56; females: 44) for leishmaniasis using the rK39 rapid antibody test and by microscopic examination. Dry blood spots (DBS) were collected from suspected cases. The samples were further analyzed using PCR targeting the internal transcribed spacer 1 (ITS1) region, followed 1 Preprint not peer reviewed This preprint research paper has not been peer reviewed. Electronic copy available at: https://ssrn.com/abstract=5242611 by sequencing for Leishmania species identification. For entomological surveys, sandfly sampling was done in the four villages where medical camps were implemented, and another four adjacent villages using CDC miniature or Silverbullet 2.0 light traps. Sandflies were identified morphologically using taxonomic keys and the speciation confirmed by PCR analysis of the cytochrome c oxidase subunit 1 (Cox1) gene and sequencing. We characterized sandfly blood feeding preference by PCR analysis of the vertebrate cytochrome-b (Cyt-b) gene, followed by HRM analysis and sequencing. Results: Ten people (10/100; 10%) tested positive for VL (eight below 15 years old - six males and two females). Of the 22 suspected cases with lesions suspected of cutaneous leishmaniasis (CL), eight were confirmed as being infected with Leishmania tropica. We trapped 4,781 sandflies and identified 1,624 specimens, consisting of 422 males and 1202 females, to species. They represented four Phlebotomus spp. and eight Sergentomyia spp. The Phlebotomus spp. included Ph. martini (8.4%; n = 136), Ph. saevus (2.2%; n = 35), Ph. orientalis (1.2%; n = 19), and Ph. guggisbergi (0.1%; n = 1). Overall, Sergentomyia species (62.7%, 1019 specimens) were abundant. Of the 450 sandflies examined for presence of Leishmania parasites by PCR, we detected DNA of Leishmania donovani in Sergentomyia clydei (n = 13), Sergentomyia adleri (n = 4), S. antennatus (n = 2), and Ph. saevus (n = 1), while L. tropica DNA was detected in Ph. saevus (n = 1). Analysis of the blood meal sources of the 68 engorged sand flies showed that most fed on humans followed by goats. We also detected blood from donkeys, mongoose and rock hyraxes. Conclusion: We confirmed L. donovani and L. tropica as the main Leishmania species responsible for VL and CL, respectively, in Kajiado. The presence of the parasites in humans and the high human blood indices in sandflies indicate active transmission and high vector human contact in the area. The co-occurrence of VL and CL is unusual and complicates case management as the two forms are managed differently, and raises the possibilities of genetic recombination in Leishmania parasites. Since access to diagnostic and treatment facilities are at the core of infectious diseases management, and elimination efforts, the establishment of two treatment Centres in Kajiado, for the first time, constitutes an important step in enhancing community access to treatment and stemming the spread of leishmaniasis in the region. This study thus contributes to global and national VL elimination targets, and demonstrates the value of coordinated outbreak preparedness.enArticle