Mpox is caused by an orthopoxvirus that occurs primarily in countries in West and Central Africa. Several animals can naturally or experimentally be infected with MPXV. Transmission of MPXV can occur from animal-to-human and from human-to-human. Spillover to humans might arise from the disruptions of the natural habitats of wild animals and can occur via various routes, including aerosol, direct contact, and fomite transmission. Infections in monkeys were first identified in captive animals in Denmark in 1958, with the first human mpox cases identified in the Democratic Republic of the Congo (DRC), Liberia, Sierra Leone and Nigeria in the beginning of the 1970s.

In six African countries, DRC (Nigeria, Liberia, Sierra Leone, Cote d’Ivoire, and Cameroon), 59 human infections were recorded between 1970 and 19808. From 1980 to 1986, over 400 cases were reported in Central and West Africa, all found in tropical rainforest locations. However, between 1972 and 1981, the instances in Congo where mpox was first reported vastly outnumbered those reported from any other country, increasing significantly from 1982 to 19847. Most recorded cases of mpox in Africa are said to have been transmitted by animals, which include rodents and less through human–human transmission. The possibility of transmission through the respiratory or mucocutaneos and inoculation or percutaneous routes or both were recorded.

The first case of Mpox in Nigeria was recorded in 1971. Until the outbreak in 1996, the most common mode of virus transmission was contact with small animals in the rainforest. A study of etiology and the sequencing of genomes; however, revealed several cases of human–human transmission in Nigeria. Human mpox cases have been recorded in 11 African countries: the DRC, Benin, the Central African Republic, Cameroon, Nigeria, the Republic of Congo, Ivory Coast, Liberia, Sierra Leone, Gabon, and South Sudan. The first incidence of the MPXV outside of Africa was during an epidemic in the United States in 2003, which was traced back to imported West African rodents. Mpox infection cases in the United Kingdom in 2018 and 2019, Israel in 2019, and Singapore in 2019 were all traced back to travelers from Nigeria.

The most severe virus outbreak in West Africa occurred in Nigeria between September and November 2017. Data collected in 2017 showed that 88 cases were confirmed, and since then, Nigeria has been reporting new cases of mpox. From its re-emergence in September 2017 to August 2018, the South-South region reported the highest number of cases. Nigeria recorded 262 suspected and 113 confirmed cases in 26 states and seven deaths in 16 states. Eight to 49 human mpox cases were recorded annually between 2019 and 2021. In the mpox outbreak, the subject matter experts for mpox at treatment centers raised the possibility of sexual transmission of mpox. Nigeria had its lowest number of reported cases in 2020 since the outbreak in 2017, with only eight recorded cases. In the spring of 2022, the disease outbreak was detected in people outside the African Continent instead of sporadic cases from travelers from endemic areas in Africa for the first time in a multi-country outbreak.

Since December 2023, there has been another outbreak of mpox in the Democratic Republic of the Congo. Tthere has been a large increase in the number of mpox cases reported in the Democratic Republic of the Congo (DRC). Since 2023 and as of 29 March 2024, DRC reported a total of 18 922 suspected mpox cases including 1,007 deaths. In 2024, and as of March 29, 4 488 cases have been reported, of which 319 have been confirmed. A total of 279 deaths have been reported in the country in 2024 (CFR: 6.7%). Mpox cases have been reported in 23 of 26 provinces of the DRC.

Currently, WHO considers the following risks for the population accordingly:

• For the general population in countries newly affected in 2022-23 or not affected mpox risk is assessed as low.
• For the general population in countries with historical mpox transmission and their neighboring countries mpox risk is assessed as moderate.
• The overall global risk for men who have sex with men and sex workers is assessed as moderate.

In March 2024, WHO published the “Surveillance, case investigation and contact tracing for mpox ‎‎(monkeypox)‎: Interim guidance”, including a new chapter on mpox reinfection, providing case definitions for suspected, probable and confirmed reinfection; also adapting more considerations relevant to endemic contexts in the African region.

With the current outbreak in the DRC, do you foresee any risk of a global spread of mpox in the near future? What measures do you suggest should be put in place to curb the outbreak in the DRC?

Resources:

1. https://www.who.int/publications/i/item/WHO-MPX-Surveillance-2024.1
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10406091/
3. https://www.ecdc.europa.eu/en/news-events/outbreak-mpox-caused-monkeypox-virus-clade-i-democratic-republic-congo