The 2024 Mpox surveillance in Senegal uncovers a large circulation of Chickenpox

During preparedness activities in Senegal to the 2024 Mpox Public Health Emergency of International Concern, a study was conducted to assess the prevalence of Varicella-Zoster virus among patients suspected of having Mpox. Samples, including skin swabs, serum, and nasopharyngeal swabs, were collected from 103 patients who presented with Mpox-like symptoms. Molecular testing via qPCR revealed that 30.1% of patients tested positive for herpesviruses, whereas no Mpox cases were detected. Common symptoms include fever, skin rash, headache, and myalgia, which closely resemble Mpox symptoms, increasing the risk of misdiagnosis. The most affected group was children under 15 years of age (50% of herpesvirus cases), followed by adults over 30 years of age (30.8%). The male/female sex ratio among herpesvirus-positive patients was 2.1, indicating a higher prevalence in males. Phylogenetic analysis of 14 newly characterized Varicella-Zoster virus genomes from metagenomic sequencing revealed that the strains circulating in Senegal were closely related to those from Guinea-Bissau, suggesting possible regional transmission. In addition, viral and bacterial coinfections were identified in Mpox-negative patients, which may have contributed to some skin lesions initially suspected to be Mpox. Our data highlight the importance of differential diagnostic testing to distinguish between Mpox and other infections, such as Chickenpox. The unexpectedly high prevalence of herpesviruses among suspected Mpox cases underscores the need for improved laboratory diagnostics, enhanced epidemiological surveillance, and targeted public health interventions to prevent misdiagnosis and improve patient management.