Risk Factors and Patterns of Treponema Infection Affecting Olive Baboons in Gombe National Park

Abstract

Treponema pallidum subsp. pertenue (TPE) causes yaws, a chronic, nonvenereal treponematosis characterized by contagious cutaneous lesions in early stages and destructive bone involvement in the tertiary stage. In the latency stage, the infection is asymptomatic with only serologic markers. A retrospective analysis of health, demographic, and behavioral records using a Generalized Linear Mixed Model (GLMM) with binomial distribution, conducted through R software to assess disease risks and trends from January 2019 to December 2024 of wild baboons at Gombe, revealed an overall clinical prevalence of 11.24% (2018/17946) across the eight studied troops. Age was a strong predictor where infants (OR = 0.05, p < 0.001), juveniles (OR = 0.27, p < 0.001), and subadults (OR = 0.65, p < 0.01) had significantly reduced odds of displaying Treponema signs compared to adults. Troops B.C and D.D exhibited elevated infection risk (OR = 2.74 and 2.63, respectively). Pregnant females (OR = 0.19, p < 0.001), wounded baboons (OR = 0.45, p < 0.001), and male immigrants (OR = 0.47, p < 0.001) were less likely to show signs. Infection signs were also lower during wet seasons (OR = 0.81, p < 0.001). Notably, the odds of infection increased consistently over time (Year OR = 1.73, p < 0.001). Understanding the ecological and demographic determinants of Treponema transmission is essential for disease surveillance, conservation, and One Health initiatives. This study presents the first long-term dataset on (TPE) infection in wild baboons from Tanzania and East Africa. Author SummaryTreponema pallidum subspecies pertenue (TPE) bacteria can cause debilitating disease in both humans and animals, yet little is known about how it spreads among wild Non-Human Primates. We studied a large population of habituated baboons and analyzed how various factors like Age, Troop, Pregnancy, Wounds, male immigration, Treatments and Interactions affect the likelihood of catching and showing signs of Treponema infection. Our analysis found that younger baboons are much less likely to show symptoms, but infection risk increases with Age. Some troops had significantly higher infection rates compared to others. Pregnant females and immigrants (Males) were less likely to show symptoms, possibly due to behavioral or biological differences. The risk of infection has also been increasing year after year. These findings suggest Treponema is becoming more common and highlight the importance of targeted monitoring and control in high-risk groups. Understanding these dynamics helps us protect wild primates and prevent cross-species transmission and potentially spill over to humans.