Mpox Current Situation: A Public Health Emergency of International Concern

Published on October 3, 2024

In August 2024, the WHO declared mpox a public health emergency of international concern (PHEIC) for the second time, this time due to an outbreak of clade 1 mpox [1]. Mpox is a zoonotic disease caused by monkeypox virus (MPXV), a member of the Orthopoxvirus genus of viruses. Before 2022, mpox (formerly known as monkeypox) had been reported mainly in countries in Central and Western Africa, but starting in May 2022, an outbreak was reported in over 100 countries, with almost 90,000 laboratory-confirmed cases globally and 152 reported deaths by August 2022 [2]. As of July 2024, the WHO had reported over 100,000 confirmed cases globally, including more than 200 deaths [3,4].

The new public health emergency is due to an outbreak of clade 1 mpox, which is more severe than its relative and has a mortality rate of approximately 5% compared to 1% or less for clade 2 mpox (the cause of the PHEIC in 2022). Clade 1 mpox is currently spreading from the Democratic Republic of the Congo (DRC), which has seen over 20,000 cases, to other countries in Africa. Individual cases have been reported in several other countries around the world, including Sweden and Thailand [5,6].

A significant issue in the current outbreak is the rate of transmission and the size of the outbreak in DRC, overwhelming response efforts, and suggesting possible differing mechanisms of transmission from the 2022 outbreak. The rapid spread started first in rural areas but is now also in urban areas, with dramatic spread in children, who account for more than 70% of the cases in the 2024 outbreak in Africa. It is well-established that children (along with pregnant women and individuals with suppressed immune systems) are highly vulnerable to the risk of severe disease and death [7,8].

The clade 2 mpox outbreak that started in 2022 remains ongoing alongside the new clade 1 outbreak. In the US alone, almost 2,000 mpox cases have been reported in 2024 to date (unreported clade), already more than double the number reported at this time in 2023 [9,10]. 

How Is It Spread?

Mpox is frequently transmitted via skin-to-skin contact from an infected person or wild animal, contact with contaminated surfaces such as bedding and clothes, and airborne transmission. The early stages are characterized by fever and other cold-like symptoms, followed by a characteristic rash with lesions that are deep-seated, painful, and well-circumscribed. Other symptoms are fever, headaches and muscle aches. Symptoms typically last 2-4 weeks, and may last longer in individuals with weakened immune systems. 

To reduce risk of mpox, avoid close contact with infected individuals, practice good air hygiene (mask appropriately, particularly in indoor spaces), and sanitize surfaces. Two smallpox vaccines, Jynneos and LC16m8, have been shown to reduce the risk of contracting mpox [11], but due to the evolving nature of outbreaks, existing vaccine efficacy in the newly emerging subclades is not well-established [12]. 

WHN has published an article on mpox response guidelines [13].

Who We Are

The WHN Science Content Team produces the WHN Newsletter and other science-based content. We are currently working on policy-relevant literature reviews on transmission in schools and air purifiers. If you would like to join us, our Slack channel is #science-content-team, and if you’re not on Slack, you can email info@whn.global or fill out our interest form at https://whn.global/join-our-science-content-team/. No formal science writing experience is necessary. 

References

[1] World Health Organization. (2024, August 26). Mpox. World Health Organization. https://www.who.int/news-room/fact-sheets/detail/mpox

[2] Dee, K., Manali, M., Bissett, L. A., Bone, J., Magill, C., Davis, C., Willett, B. J., & Murcia, P. R. (2024). Smallpox vaccination campaigns resulted in age-associated population cross-immunity against monkeypox virus. Journal of General Virology, 105(6). https://doi.org/10.1099/jgv.0.001999

[3] World Health Organization. (2024, September 17). 2022-24 mpox (Monkeypox) outbreak:global trends. World Health Organization. https://worldhealthorg.shinyapps.io/mpx_global/

[4] Andrianou, X. & Skoglund, J. M. (2024, September 2). Epidemiological update – Week 35/2024: Mpox due to monkeypox virus clade I. European Centre for Disease Prevention and Control. https://www.ecdc.europa.eu/en/news-events/mpox-epidemiological-update-monkeypox-2-september-2024

[5] Ancona, A., Andrianou, X., Bacci, S., Cauchi, D., Cenciarelli, O., Reyes, J., & Spiteri, G. (2024, August 26). Epidemiological update: Mpox due to monkeypox virus clade I. European Centre for Disease Prevention and Control.  https://www.ecdc.europa.eu/en/news-events/epidemiological-update-mpox-due-monkeypox-virus-clade-i

[6] Centers for Disease Control and Prevention. (2024, August 22). Fact sheet: United States response to the clade I mpox outbreak in several African countries. Centers for Disease Control and Prevention. https://www.cdc.gov/media/releases/2024/s0822-mpox-outbreak.html).

[7] Africa Centres for Disease Control and Prevention. (2024, September 19). Mpox situation in Africa: Guidance for schools and childcare facilities. Africa Centres for Disease Control and Prevention. https://africacdc.org/download/mpox-situation-in-africa-guidance-for-schools-and-childcare-facilities/

[8] UNICEF. (2024, August 16). Children at significant risk from surging mpox outbreak in the Democratic Republic of the Congo. UNICEF. https://www.unicef.org/press-releases/children-significant-risk-surging-mpox-outbreak-democratic-republic-congo-unicef

[9] Centers for Disease Control and Prevention. (2024, September 13). Ongoing Clade II Mpox Global Outbreak. Centers for Disease Control and Prevention. https://www.cdc.gov/mpox/outbreaks/2022/index-1.html?CDC_AAref_Val=https://www.cdc.gov/poxvirus/mpox/outbreak/2022-ongoing-global.html 

[10] Centers for Disease Control and Prevention. (2024, August 31). Nationally notifiable infectious diseases and conditions, United States: Weekly tables. CDC. https://wonder.cdc.gov/nndss/static/2024/35/2024-35-table968.html

[11] Wolff Sagy, Y., Zucker, R., Hammerman, A., Markovits, H., Arieh, N. G., Abu Ahmad, W., Battat, E., Ramot, N., Carmeli, G., Mark-Amir, A., Wagner-Kolasko, G., Duskin-Bitan, H., Yaron, S., Peretz, A., Arbel, R., Lavie, G., & Netzer, D. (2023). Real-world effectiveness of a single dose of mpox vaccine in males. Nature Medicine, 29(3), 748–752. https://doi.org/10.1038/s41591-023-02229-3

[12] Reardon, S. (2024). Mpox is spreading rapidly. Here are the questions researchers are racing to answer. Nature, 633(8028), 16–17. https://doi.org/10.1038/d41586-024-02793-9

[13] World Health Network. (2024, August 19). MPOX response guidelines. WHN. https://whn.global/monkeypox-response-guidelines/