Prevalence and associated factors of severe mpox in Mbarara City, southwestern Uganda, October 2024-May 2025.

BACKGROUND

In October 2024, Mbarara City, Uganda, experienced sustained mpox transmission, with Nyamityobora Ward being disproportionately affected. Data on factors associated with severe disease were limited. We determined the prevalence and factors associated with severe mpox in Nyamityobora Ward during October 2024-May 2025.

METHODS

We conducted a cross-sectional study using active case finding among suspected mpox cases in Nyamityobora Ward from April to May 2025. Disease severity was assessed using an adapted Mpox Severity Scoring System (MPSSS) and dichotomized as severe versus non-severe. Modified Poisson regression was used to identify associated factors.

RESULTS

Of 106 mpox cases identified, 62 (59%) had severe disease. The median age was 29 years and 55% were female. HIV co-infection (adjusted prevalence ratio [aPR] 1.8, 95% CI: 1.2-2.7), delayed care-seeking >5 days (aPR 1.5, 95% CI: 1.1-2.1) and sex work (aPR 1.4, 95% CI: 1.0-2.0; P = 0.045) were independently associated with severe mpox.

CONCLUSION

Severe mpox was common and strongly associated with HIV co-infection, delayed care-seeking and sex work. Integrating mpox screening into HIV services and promoting early care-seeking and implementing targeted interventions for sex workers may reduce severe outcomes during outbreaks.