Shifting transmission patterns of human mpox in South Kivu, DR Congo
Authors: Patrick DMC Katoto, Winters Muttamba, Esto Bahizire, Espoir Bwenge Malembaka, Henry Kyobe Bosa, Dieudonné Mwamba Kazadi, Gaston Lubambo, Freddy Belesi Siangoli, Barnabas Bakamutumaho, Misaki Wayengera, Don Jethro Mavungu Landu, Daniel Mukadi-Bamuleka, Placide Mbala, Mark Loeb, Bruce Kirenga, Jean-Jacques Muyembe-Tamfum
Journal: The Lancet Infectious Diseases (2024)

In the wake of the COVID-19 pandemic, humanity experienced the emergence of another epidemic health threat in 2022. That threat came from human mpox (formerly known as monkeypox) virus—an agent that despite its discovery in 1958, has historically received low attention until recent developments. First reported in humans in 1970, there has since been renewed interest in the disease due to altered transmission and spread mechanisms, and the increased number of cases in 2022.1WHOWHO Director-General declares the ongoing monkeypox outbreak a Public Health Emergency of International Concern.https://www.who.int/europe/news/item/23-07-2022-who-director-general-declares-the-ongoing-monkeypox-outbreak-a-public-health-event-of-international-concernDate: July 23, 2022Date accessed: February 2, 2024Google Scholar WHO declared mpox outbreak a Public Health Emergency of International Concern (PHEIC), following rapid and sustained spread beyond the endemic countries and increases in the number of cases in clusters. Following the decline in number of cases, in May 2023, WHO downgraded the mpox outbreak as no longer a PHEIC. Despite this declaration, cases continue to be reported in several countries. Although earlier transmission of mpox was endemic to sub-Saharan Africa and driven by either zoonotic spread from human interactions with monkeys or casual contact among infected humans, in 2022 the world witnessed the emergence of a potential global pandemic driven by sexual contact among men who have sex with men (MSM).2WHOMpox (monkeypox) - Democratic Republic of the Congo.https://www.who.int/emergencies/disease-outbreak-news/item/2023-DON493Date: Nov 23, 2023Date accessed: April 16, 2024Google Scholar In September 2023, the re-emergence of mpox with an epidemiological profile suggestive of heterosexual transmission and spread was noted in the province of South Kivu, in DR Congo. Previously, there had been an indication that the transmission in DR Congo was driven by homosexual interaction.2WHOMpox (monkeypox) - Democratic Republic of the Congo.https://www.who.int/emergencies/disease-outbreak-news/item/2023-DON493Date: Nov 23, 2023Date accessed: April 16, 2024Google Scholar This commentary describes the epidemiology of the current mpox outbreak in South Kivu using routine surveillance data and highlights what appears to be altered transmission dynamics from the traditional human–wild interactions and casual human-to-human transmission, to heterosexual transmission and the likely implications for cross border and potential global spread. Between Sept 28, 2023 and March 3, 2024, 226 suspected mpox cases were investigated in South Kivu. The most common signs or symptoms included: skin eruption (100%), fever (59%), lymphadenopathy (40%), sore throat (26%), headache (23%), cough (22%), muscle pain (22%), and mouth ulcers (14%), with no sex difference. More than half of the cases were women (53·8%), a result that diverges from previous studies where men were predominantly affected, yet aligns with the current epidemiology of Clade I in Central Africa.3Benites-Zapata VA Ulloque-Badaracco JR Alarcon-Braga EA et al.Clinical features, hospitalisation and deaths associated with monkeypox: a systematic review and meta-analysis.Ann Clin Microbiol Antimicrob. 2022; 21: 36Crossref PubMed Scopus (86) Google Scholar It appears apparent that heterosexual transmission could be driving the transmission rates in this region, unlike homosexual transmission especially in MSM, which was the main driver for the high infection rates in 2022.2WHOMpox (monkeypox) - Democratic Republic of the Congo.https://www.who.int/emergencies/disease-outbreak-news/item/2023-DON493Date: Nov 23, 2023Date accessed: April 16, 2024Google Scholar High prevalence in women could complicate control by introducing another route of transmission—ie, vertical transmission, which presents with adverse pregnancy outcomes.4Fahrni ML Priyanka Choudhary OP Possibility of vertical transmission of the human monkeypox virus.Int J Surg. 2022; 105106832Crossref Scopus (10) Google Scholar Furthermore, evidence of heterosexual transmission spread is supported by the fact that currently, female sex workers constitute a big proportion of cases (29%) in this cluster (figure). Although it has been postulated that mpox could be sexually transmitted, this would be via the homosexual route, and largely among MSM.5Thornhill JP Barkati S Walmsley S et al.Monkeypox virus infection in humans across 16 countries – April–June 2022.N Engl J Med. 2022; 387: 679-691Crossref PubMed Scopus (1114) Google Scholar The findings from this cohort suggest increased risk of transmission associated with heterosexual (92%) and homosexual transmission (4%), with women largely affected. The shift might be due to Clade I's predominance and severity in DR Congo compared with Clade II, which is milder and more common in Western countries and Nigeria, influencing the outbreak among MSM.6Centres for Disease Control and PreventionAbout mpox.https://www.cdc.gov/poxvirus/mpox/about/index.htmlDate: April 18, 2024Date accessed: April 16, 2024Google Scholar Whether or not sexual contact by itself serves as a route of transmission or simply enhances transmission by associated skin-to-skin contact remains to be fully investigated. Regardless, these findings have implications for control of sexually transmitted infections in a region where the prevalence of HIV among women remains high,7US Agency for International DevelopmentDemocratic Republic of the Congo and HIV/AIDS.https://pdf.usaid.gov/pdf_docs/Pnacp013.pdfDate: June, 1999Date accessed: April 16, 2024Google Scholar which is further exacerbated by sexual violence associated with armed conflict in the region. The median age of the patients was 21 years, with most (59%) aged between 15–29 years. This finding is in keeping with what has been reported recently, a rise in median age of patients as opposed to earlier years where young children were the most affected.8Ogoina D Iroezindu M James HI et al.Clinical course and outcome of human monkeypox in Nigeria.Clin Infect Dis. 2020; 71: e210-e214Crossref PubMed Scopus (295) Google Scholar However, the median age is lower than what has been found elsewhere.5Thornhill JP Barkati S Walmsley S et al.Monkeypox virus infection in humans across 16 countries – April–June 2022.N Engl J Med. 2022; 387: 679-691Crossref PubMed Scopus (1114) Google Scholar This finding could be explained by waning immunity from smallpox vaccination9Akter F Hasan TB Alam F et al.Effect of prior immunisation with smallpox vaccine for protection against human mpox: a systematic review.Rev Med Virol. 2023; 33e2444Crossref PubMed Scopus (7) Google Scholar in this predominantly young artisanal mining population, alongside potential sexual transmission. The shift in transmission dynamics and the prevalence in at-risk groups is reminiscent of the historical emergence of the HIV AIDS epidemic that was originally postulated to have transferred over from monkeys to humans,10McClure MO Schulz TF Origin of HIV.BMJ. 1989; 298: 1267-1268Crossref PubMed Google Scholar with its initial high prevalence predominating among MSM and later transitioning majorly by heterosexual contact transmission. Similarly, the possibility of cross-border transmission, initially in Uganda given the porosity of borders, remains high because of informal workers around mines and increased mass movement arising from insecurity. In 2022 alone, over 60 000 refugees crossed into Uganda from DR Congo and this mass movement continues. The shifting transmission dynamics of the mpox outbreak in South Kivu stresses the imperative for adaptable and innovative global health strategies. These strategies should emphasise enhanced local detection capabilities, potentially by deploying mobile clinics for onsite testing rather than relying on sample transportation to distant laboratories. Innovations in case management, such as the strategic use of antiviral medications alongside personalised and risk-informed community engagement approaches, are pivotal for tackling the resurgence of mpox. Furthermore, there is an urgent need to expedite the research, development, and dissemination of effective mpox vaccines to safeguard at-risk populations worldwide. An innovative approach could also include leveraging digital-health technologies for real-time surveillance and using artificial intelligence to predict outbreak patterns, thus enhancing both preventive measures and response strategies. We declare no competing interests.