Epidemiological characteristics of monkeypox virus Clade Ib in the Democratic Republic of the Congo - Received 5 June 2025

Sep 30, 2026

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Monkeypox virus (MPXV) Clade Ib, linked to sustained human-to-human transmission, emerged in eastern DRC in late 2023, with early spread largely among adults through sexual contact. The study compares key epidemiological features by transmission mode, estimating a mean serial interval of 8.57 days and a mean incubation period of 9.56 days. Serial interval and incubation estimates are about four and two days shorter, respectively, for putative sexual versus non-sexual transmission, implying that outbreak context is crucial for public health policy design.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages8

Reading Time20 min

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Abstract

Introduction and background

MPXV Clade Ib emergence and transmission

Role of serial interval and incubation period

Article [https://doi.org/10.1038/s41467-025-66875-6](https://doi.org/10.1038/s41467-025-66875-6) Epidemiological characteristics of monkeypox virus Clade Ib in the Democratic Republic of the Congo Received: 5 June 2025 | Accepted: 18 November 2025 | | --- | | | | Check for updates | Cécile Kremer 1 , Sabin Sabiti Nundu2,3, Emmanuel Hasivirwe Vakaniaki2,3, Isabel Brosius 2, Guy Mukari3, Papy Munganga3, Eugene Bangwen 2,4, Jean Claude Tshomba3, Yves Mujula3, Elise De Vos2, Christophe Van Dijck 2,4, Sarah Houben2, Oswaldo Gressani 1, Cris Kacita5, Daniel Mukadi-Bamuleka 3,6,7, Tony Wawina-Bokalanga2,3,7, Eddy Kinganda-Lusamaki 3,8, Adrienne Amuri-Aziza 2,3, Patrick Mutombo Lupola 7, Jean-Jacques Muyembe-Tamfum2,7, Placide Mbala-Kingebeni 2,7,10, Laurens Liesenborghs 2,4,10, Niel Hens 1,9,10 & Andrea Torneri 1,10 Monkeypox virus (MPXV) Clade Ib, a new MPXV subclade associated with sustained human-to-human transmission, emerged in eastern DRC in late 2023. Early spread mainly occurred among the adult population, primarily through sexual contact. We investigate how key epidemiological characteristics ofthe new MPXV Clade Ib outbreak in the DRC differ by transmission mode. We estimate the mean serial interval to be 8.57 days (95% CI 7.15 − 9.91 days). The serial interval is approximately four days shorter for putative sexual compared to non-sexual transmission. We estimate the mean incubation period to be 9.56 days (95% CrI 8.22 − 11.02 days), and approximately two days shorter for putative sexual compared to non-sexual transmission. These observed differences in serial interval and incubation period estimates by transmission mode suggest that the context in which an outbreak occurs is an essential factor to consider when devising public health policies. Mpox is a zoonotic viral disease characterized by fever, lymphadenopathy, and a vesiculopustular rash, caused by the monkeypox virus (MPXV), an orthopoxvirus (OPXV) related to variola virus. In late 2023, after decades of repeated mpox outbreaks in the Democratic Republic of the Congo (DRC), a new variant of MPXV Clade I emerged in Kamituga, a mining town in South Kivu province. Kamituga is a mining city with a population of around 241,642, and an estimated 20,000 people directly work in the artisanal and small-scale gold mining sector. Mining plays a key role in the livelihood of the local economy, making the city a popular destination that is ﬁlled with migrant 1Data Science Institute, I-BioStat, Hasselt University, Hasselt, Belgium. 2Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium. 3Institut National de Recherche Biomédicale (INRB), Kinshasa, Democratic Republic of the Congo. 4Department of Microbiology, Immunology and Transplantation, KU Leuven, Leuven, Belgium. 5Programme National de Lutte contre le Mpox et les Fièvres Hémorragiques Virales (PNLMPOX-FHV), Ministry of Public Health, Kinshasa, Democratic Republic of the Congo. 6Rodolphe Mérieux Institut National de Recherche Biomédicale Goma Laboratory, Goma, Democratic Republic of the Congo. 7Service de Microbiologie, Département de Biologie Médicale, Cliniques Universitaires de Kinshasa, Université de Kinshasa, Kinshasa, Democratic Republic of the Congo. 8Institut de Recherche pour le Développement (IRD), Université de Montpellier, Montpellier, France. 9Centre for Health Economics Research and Modelling of Infectious Diseases, Vaccine& Infectious Disease Institute, University of Antwerp, Antwerp, Belgium. 10These authors jointly supervised this work: Placide Mbala-Kingebeni, Laurens Liesenborghs, Niel Hens, and Andrea Torneri. e-mail: [cecile.kremer@uhasselt.be](cecile.kremer@uhasselt.be) workers and people searching for economic opportunities. In mid-June 2024, Goma, in the North Kivu province of the DRC, experienced its ﬁrst Clade Ib infections. Goma is a densely populated city of approximately two million inhabitants, comprising more than a dozen refugee camps wh

FAQs

What is the main focus of the study on MPXV Clade Ib in the DRC?

The study investigates how key epidemiological characteristics of the MPXV Clade Ib outbreak differ by transmission mode, emphasizing transmission-related delays.

How is the serial interval defined in the document?

The serial interval is defined as the time between symptom onset in a primary case and symptom onset in a secondary case.

What do the results suggest about differences by transmission mode?

The serial interval and incubation period estimates are shorter for putative sexual transmission than for non-sexual transmission, indicating outbreak context matters for designing public health policies.

Sep 30, 2026

Uploaded by Ophelia