Widespread transmission in diverse ecotypes challenges visceral leishmaniasis control in East Africa

Publication Type

Journal Article

Journal Name

medRxiv : the preprint server for health sciences

Eva Iniguez, Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
Mercy Tuluso, Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi 00200, Kenya.
Steve Kiplagat, International Centre of Insect Physiology and Ecology (icipe), Nairobi 30772-00100, Kenya.
Araya Gebresilassie, Department of Zoological Sciences, College of Natural and Computational Sciences, Addis Ababa University, Addis Ababa 1176, Ethiopia.
Esayas Aklilu, Vector Biology and Control Research Unit, Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa 1176, Ethiopia.
Olivia Battistoni, Departments of Pathology and Microbiology, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA.
Johnstone Ingonga, Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi 00200, Kenya.
John Mark Makwatta, International Centre of Insect Physiology and Ecology (icipe), Nairobi 30772-00100, Kenya.
Mohamed Alamin, Department of Zoology, Faculty of Science, University of Khartoum, Khartoum 11111, Sudan.
Osman Dakien, Department of Zoology, Faculty of Science, University of Khartoum, Khartoum 11111, Sudan.
Alphine Chebet, Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi 00200, Kenya.
Esther Kaunda, Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi 00200, Kenya.
Patrick Huffcutt, Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
Serena Doh, Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
Pedro Cecilio, Vector Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville 20852, MD, USA.
Galgallo Bonaya, International Centre of Insect Physiology and Ecology (icipe), Nairobi 30772-00100, Kenya.
Claudio Meneses, Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
Tiago D. Serafim, Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
Myrthe Pareyn, Department of Clinical Sciences, Institute of Tropical Medicine Antwerp 2000, Belgium.
Mohamed Osman, York Biomedical Research Institute, University of York, York YO10 5DD, UK.
Eltahir A. Khalil, Department of Zoology, Faculty of Science, University of Khartoum, Khartoum 11111, Sudan.
Omran F. Osman, Department of Zoology, Faculty of Science, University of Khartoum, Khartoum 11111, Sudan.
Brima M. Younis, Department of Zoology, Faculty of Science, University of Khartoum, Khartoum 11111, Sudan.
Sithar Dorjee, Faculty of Postgraduate Medicine, Khesar Gyalpo University of Medical Sciences of Bhutan, Thimphu 11001, Bhutan.
Guofa Zhou, Program in Public Health, University of California at Irvine, Irvine, CA 92697, USA.
Jesus G. Valenzuela, Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
Dan K. Masiga, International Centre of Insect Physiology and Ecology (icipe), Nairobi 30772-00100, Kenya.
Ahmed M. Musa, Department of Clinical Pathology and Immunology, Institute of Endemic Diseases, University of Khartoum, Khartoum 11111, Sudan.
Asrat Hailu, College of Health Sciences, Addis Ababa University, Addis Ababa 1000, Ethiopia.

Publication Date

11-24-2025

Abstract

East Africa is emerging as the global hot spot of visceral leishmaniasis (VL), yet efforts to eliminate it are hindered by substantial knowledge gaps in its ecoepidemiology. Here, we report on the high prevalence of Leishmania infection in Phlebotomus orientalis in Marsabit county, Kenya (3.9%), and Gedaref state, Sudan (3.6%), where this species comprised 99.8% (n = 1185) and 100% (n = 1350) of captured Phlebotomus females, respectively. In Aba Roba, Ethiopia, Ph. martini accounted for 99% of 184 collected Phlebotomus females and had a lower infection rate of 1.5%. Ph. orientalis and Ph. martini exhibited different habitat and feeding preferences. While Ph. orientalis was abundant in diverse peridomestic and sylvatic microhabitats, Ph. martini was predominantly collected from termite hills. Moreover, Ph. orientalis primarily fed on humans and less on domestic and sylvatic animals. In contrast, Ph. martini exhibited zoophagic behavior, mostly feeding on cows and Ovis. Widespread transmission of Leishmania in our study sites is supported by high rK39 seroprevalence in both Kenya (17.9%) and Sudan (6.22%). An observed greater prevalence of antibodies to rK39 in individuals living near than away from VL cases in both Kenya (19.8% versus 7.41%, P = 0.0015) and Sudan (8.4% versus 2.1%, P = 0.0105) demonstrated that proximity to a VL case carries an increased risk of infection. Our findings highlight the need for a risk-based targeted site-specific elimination strategy that accounts for the intensity, diversity, and complexity of VL transmission in today's East Africa.

Keywords

East Africa, Leishmania-infected sand flies, Sand fly ecology, rK39 seroprevalence, visceral leishmaniasis

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