Background
Mpox, a zoonotic disease caused by the Monkeypox virus (MPXV) within the Orthopoxvirus family, includes two major clades: Clade I, associated with severe disease and higher mortality, and Clade II. On August 14, 2024, the World Health Organization (WHO) declared Mpox a public health emergency of international concern following multi-country outbreaks since May 2022. Uganda declared a Mpox outbreak on August 2, 2024. With increasing case counts, sexually mediated clusters, and sustained human-to-human transmission, this study aimed to characterize the epidemiology, clinical presentations, and genetic diversity of Mpox cases confirmed in Uganda from July to October 2024.
Methods
This cross-sectional study analyzed data from the national Results Dispatch System (RDS) for Mpox cases reported between July 22 and October 31, 2024. Extracted data included patient demographics, symptom onset dates, symptoms, sample collection dates, sample types, test results, epidemiological exposure links, and whole-genome sequencing results.
Results
A total of 323 Mpox cases were confirmed from 1,991 samples tested (positivity rate: 16%) across 35 districts (24% of Uganda’s 146 districts), with Kampala reporting the highest case burden (41%). The median age was 24 years (IQR: 17), and 28% of cases involved children (0–17 years). Males accounted for 55% of cases. Symptom onset began on July 12, 2024, with a median delay of 4 days (IQR: 6) to sample collection. Common symptoms included rash (92%), fever (85%), and lymphadenopathy (78%). Atypical genital lesions were observed in 25% of cases within sexually mediated clusters. Close contact with infected individuals was reported in 60% of cases. Genomic analysis classified all positive samples as Clade 1b, with five distinct subclades, and no APOBEC3-like mutations were identified. No associations were found between clustering and variables such as district, gender, and collection batch.
Conclusions
The Mpox outbreak in Uganda was primarily driven by behavioral and environmental factors, emphasizing the importance of targeted interventions to address sexual transmission dynamics and protect vulnerable populations. While viral evolution resulted in five subclades, transmission was not linked to specific demographic or geographic factors, indicating widespread dissemination.