Background
The Africa CDC and the WHO declared Mpox a Public Health Emergency of Continental Security and of International Concern respectively. The first Mpox-positive cases in Uganda were reported in July 2024 from Kasese District, Bwera Hospital by the Uganda Virus Research Institute (UVRI) and MRC/UVRI & LSHTM Uganda Research Unit. In light of ongoing Mpox virus (MPXV) transmission and an increasing number of cases reported in the neighboring DRC, we heightened surveillance for MPXV infections in Uganda to mitigate against the increased public health risk of cross-border spillover.
Methods
In this cross-sectional study, we tested samples collected from suspected Mpox cases on real-time PCR using different platforms to increase accuracy. All Mpox-positive samples were subsequently genotyped using targeted enrichment next-generation sequencing (NGS) while unbiased metagenomic NGS was performed on the Mpox-negative samples from clinically suspected cases to characterize other pathogens. Phylogenetic analysis was performed using IQTREE.
Results
As of 24-09-2024, 24 specimens tested positive for Mpox virus (MPXV) on real-time PCR out of the 597 samples collected from clinically suspected cases. Twenty of the 24 positives (83%) were detected at UVRI and near full-length Mpox genomes were generated for 8 samples with a genome coverage of >99%. Phylogenetic analysis showed that Ugandan sequences were closely genetically related to clade Ib sequences from the DRC suggesting a close link to the Sudan-Kivu Mpox outbreaks (Figure 1). Differential testing using unbiased deep sequencing of suspected Mpox cases that tested PCR-negative (n=73) detected human herpesvirus 3 as the top viral hit present in the samples (genome coverage of 90-100%) (Figure 1).
Conclusions
The Mpox outbreak in Uganda suggests an epidemiologic link to clade Ib MPXV associated with recent South Kivu Mpox outbreaks in the Democratic Republic of Congo (DRC). An increase in Mpox positivity is likely due to increasing community transmissions and findings from differential testing of Mpox-negative samples suggests co-circulation of Mpox and Chickenpox viruses, highlighting the need for routine surveillance of other emerging and re-emerging infections.