Field-Based Analysis of Sodalis glossinidius -Trypanosome Co-infection in Wild Tsetse Flies from Kagarko and Ijah Gwari, Nigeria

Abstract

This study investigated Sodalis glossinidius-trypanosome interactions in wild tsetse populations from Nigeria using morphological and molecular approaches. Analysis of 1,611 flies revealed Glossina palpalis palpalis as dominant (81.6%), with higher wet-season abundance. Trypanosome infections peaked in wet seasons, notably Trypanosoma vivax (36.7–47.4%) and T. brucei (19.3–30.6%). qPCR demonstrated significantly lower Ct values in Sodalis-positive flies (mean Ct = 22.1) Sodalis- negatives (Ct = 28.6, p < 0.0001), corresponding to a 66-fold higher trypanosome load (4.2 × 10⁵ vs. 6.3 × 10³ copies/µL). Melting curve analysis confirmed specificity, with Sodalis-positives showing sharp peaks at 85°C versus broader peaks (87°C) in negatives. Sodalis prevalence was significantly higher in wet seasons (OR > 2.0), and coinfection analysis revealed strong Sodalis-T. brucei association in G. palpalis (53.1%, OR = 1.23, p = 0.021), contrasting with an inverse Sodalis T. congolense savannah relationship (OR = 0.76). Site-specific variations underscored ecological influences on these interactions. The tight clustering of Ct values and distinct melting profiles in Sodalis-positive flies suggests symbiont-mediated facilitation of trypanosome proliferation, likely through immune modulation. These findings provide field evidence that Sodalis enhances trypanosome transmission potential in tsetse populations. The qPCR and melting curve data validate the robustness of these associations, highlighting Sodalis as a key target for innovative disease control strategies.