Non-exanthematous mpox and the implications on response measures during outbreaks.

Abstract

In 2024, mpox was declared a public health emergency. Several response measures have since been implemented by health authorities in the affected countries to control the outbreak. Our perspective was triggered by an article in the special issue on the surge of mpox in Africa that highlighted rashless or non-exanthematous presentations of mpox in Nigeria. Although these have been previously highlighted, especially during the global outbreak in 2022, the contribution of these factors to the general outbreak dynamics remains poorly understood. We reflect on the possible implications of this outbreak and strategies to address it in the context of a newer clade 1b responsible for the current upsurge, where no prevalence studies of rashless mpox have been done. Using our experiences, we also discuss how diagnostic expectations centred on the presence of rash may hinder timely detection, response, and reporting. Moreover, current outbreak situation reports do not disaggregate cases by symptom profile (for example, rash-presenting versus rashless), a gap that undermines a comprehensive understanding of the actual burden of mpox. Finally, we analyse the potential implications of undetected spread, surveillance, vaccination strategies and risk communication and behavioural change practices, to help break the chains of transmission that might have been missed.