Xenodiagnosis and Infection Rate of Trypanosoma brucei in Glossina Vectors of Kogi-Benue Confluence Zone

The Kogi-Benue confluence zone represents a historically documented focus of human African trypanosomiasis in Nigeria, and contemporary assessment of trypanosome infection rates in Glossina vectors is essential for determining current transmission risk. This study employed xenodiagnosis and molecular methods to determine Trypanosoma brucei infection rates in Glossina populations in the Kogi-Benue confluence zone, North Central Nigeria. A total of 560 Glossina fuscipes flies were collected using biconical traps across eight riverine sites over six months. DNA was extracted from dissected salivary glands and midguts, and nested PCR targeting the ITS1 region of ribosomal DNA was used for Trypanosoma detection and species identification. Sub-Saharan African cattle were used for xenodiagnosis to confirm infectivity of fly-derived trypanosomes. Trypanosome infection was detected by PCR in 6.8 percent of flies. Trypanosoma brucei was the dominant species at 52.6 percent of positive flies, with T. congolense and T. vivax also identified. No T. b. rhodesiense was detected. Xenodiagnosis confirmed viable transmission-stage trypanosomes in 61.1 percent of T. brucei-positive fly midguts. The study provides updated entomological risk data for the Kogi-Benue zone and recommends active human case-finding in adjacent communities as part of post-elimination surveillance in North Central Nigeria. Keywords: Trypanosoma brucei, Glossina, xenodiagnosis, human African trypanosomiasis, Kogi-Benue confluence.