On 14 August 2024, the World Health Organization (WHO) declared the current situation regarding the mpox virus to be a Public Health Emergency of International Concern (PHEIC). (The original declaration can be consulted at the following address:https://www.who.int/news/item/14-08-2024-who-director-general-declares-… )
Mpox is not a new virus. It has been known to infect humans since the 1970s. It was previously referred to as monkeypox, because monkeys were accidentally infected, and the name was recently changed to ‘mpox’. The natural reservoir of the virus is not monkeys, but rodents endemic to West, Central and East Africa. In these regions, there has been an increase in mpox cases since vaccination against human smallpox ceased in the 1980s, a trend that has worsened since the global epidemic of 2022.
The sharp increase in the number of cases reported in the Democratic Republic of Congo (DRC) and a growing number of previously unaffected neighbouring countries, and the appearance of a new clade of the virus (a new strain that has evolved), called Clade Ib, prompted the declaration of the UPPPI. In 2022, the UPPSI had already been declared when a global epidemic of another clade (IIb) was identified, which mainly affected men who declared having sex with men and/or numerous sexual partners. This epidemic was brought under control by vaccination and public health measures outside endemic areas, but the virus continues to circulate quietly around the world.
There are currently 3 major strains of the virus in circulation:
- Clade Ia in Central Africa
- Clade Ib: eastern DRC and neighbouring countries (Uganda, Kenya, Burundi and Rwanda)
- Clade II: West Africa and the global epidemic of 2022 (clade IIb)
Several epidemics caused by different strains are underway simultaneously in many countries, with distinct modes of transmission and levels of risk. Uncertainties remain concerning the case-fatality rate, morbidity and transmissibility of the different strains of the virus, given the paucity of existing data on mpox and on the current epidemic in East Africa.
The virus is transmitted by direct contact (e.g. injured skin or mucous membranes) with lesions or secretions from infected people or animals. Transmission occurs mainly by:
- Zoonotic transmission: (in particular Clade Ia)
- Prolonged sexual or non-sexual contact, (mainly Clade Ib and Clade IIb)
- Transmission during pregnancy from mother to child (with significant risk of foetal death).
Current challenges in the region include a lack of access to diagnostic tests, vaccines and treatments. The WHO and other partners are working with countries and manufacturers to address this need and bring the epidemic under control.
The overall risk to the general public is currently considered low by the ECDC for the EU/EEA. It is likely that cases will be diagnosed in Switzerland and Europe over the coming weeks.
Our Centre is actively involved in the diagnostic validation of mpox tests with our partner FIND and as part of our activities as a WHO Collaborating Centre.
Our reference laboratory, CRIVE, is able to test samples if clinical suspicion arises.
In addition, clinical studies on mpox are currently underway at the HUG.
More information is available on the CMVE website.