Human Monkeypox Outbreak in Non-Endemic Countries: The Need for Global Health Action

Abstract

Monkeypox (MPX) is a re-emerging zoonotic disease caused by the MPX virus (MPXV), a member of the orthopoxvirus genus of the poxviridae family. Before 2022, local transmission of MPX was essentially limited to the rainforest regions of Central and West Africa where the disease is known to be endemic1. The MPXV is a large DNA virus that is very stable and more efficient than many RNA viruses at detecting and repairing mutations. This makes the virus less prone to higher transmissibility unlike RNA viruses such as SARS-CoV-22. Prior to the 2022 outbreak, two distinct clades of the MPXV were recognized: the Congo Basin (Central African) and the West African clades, otherwise known as Clades I and II in the newly proposed nomenclature. The Congo Basin clade is associated with a higher transmission rate and higher case fatality rate (CFR) of about 11% compared to the West African clade with an estimated CFR of 1%2. The first case of MPX in the ongoing 2022 epidemic among non-endemic countries was reported in the United Kingdom (UK) by the UK Health Security Agency (UKHSA) on 7 May 2022, in a returning traveler from Nigeria. Subsequent cases discovered one week later in London were unrelated to the index case and had no travel links to endemic regions in Africa3. Since then, the World Health Organization (WHO) has reported more than 64,300 cases outside Africa in over 90 countries across Europe, the Americas and the West Pacific Regions4. On 23 July 2022, the WHO declared MPX a Public Health Emergency of International Concern (PHEIC). A newly discovered Clade IIb among the circulating strains of MPXV in non-endemic countries has been reported to have similarities with the West African clade but with higher transmissibility1. The WHO projects detection of more cases as surveillance is enhanced to involve more non-endemic countries4. This is surprisingly occurring at a time several countries are lifting COVID-19 pandemic lockdowns with increased international travels.