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Mpox Outbreaks in the Central African Republic

Genomic surveillance reveals animal-to-human spillovers as main driver

Mpox continues to pose a growing health threat in various African countries, such as the Democratic Republic of the Congo, where frequent zoonotic spillovers occur across the country and occasionally lead to major outbreaks associated with the emergence of viral lineages whose spread is supported by human-to-human transmission. From August 2024 to September 2025, the World Health Organization had declared mpox a public health emergency, highlighting the urgent need to understand its spread across the region. The drivers behind recent mpox outbreaks in the Central African Republic, where the disease is endemic, had previously been unclear—until now. 

A new genomic epidemiology study led jointly by Prof. Fabian Leendertz, Director of the Helmholtz Institute for One Health (HIOH) – a site of the Helmholtz Centre for Infection Research (HZI), Prof. Yap Boum II and Prof. Emmanuel Nakoune from the Institut Pasteur de Bangui (IPB) as well as Prof. Sebastien Calvignac-Spencer (HIOH), sheds light on the drivers behind recent outbreaks of mpox (formerly known as monkeypox) in the Central African Republic, one of the countries most affected by clade I monkeypox viruses in recent years. Dr Christian Noël Malaka from the IPB and Dr Livia Victoria Patrono from the HIOH, the first authors of this study, worked side by side to establish genomic surveillance for mpox at IPB in Bangui. The study was published in the journal The Lancet Microbe.

The team analyzed 46 clinical samples collected between 2022 and 2024 from mpox cases detected across eight prefectures in the Central African Republic. Utilizing hybridization capture coupled with high-throughput sequencing, they assembled 41 nearly complete viral genomes from different regions of the country, including the capital city of Bangui. 

Their findings reveal a striking pattern: most outbreaks were caused by independent spillovers of distinct viral strains from unknown animal reservoirs to humans, particularly in rural regions. These outbreaks appear to be short-lived and with limited spread from person to person.

In the capital city of Bangui, however, the situation may be more complex. On a single day in July 2024, three genetically distinct viruses were detected, suggesting multiple introductions into the city, possibly linked to movement of people or bushmeat trade from other regions.

Ornella Sibiro, Ella Farra, and Sandra Garba-Ouangolé preparing samples for high-throughput sequencing in the laboratories of the Genomic Surveillance Platform of the Institut Pasteur de Bangui, Central African Republic. ©IPB and HIOH

“While the data generated until now suggests that human-to-human transmission has remained limited, the high frequency of spillover events is concerning,” says Dr Livia Victoria Patrono, staff scientist in HIOH’s Department ”Ecology and Emergence of Zoonotic Diseases”. “It underscores the urgent need to identify the animal sources of the virus and the behaviors associated with exposure, and to develop measures to reduce opportunities for cross-species transmission at the local level. At the same time, recent evidence from neighboring DRC shows that if the virus enters a conductive network it may spread efficiently among humans, highlighting the need of strong surveillance systems.”

The research provides important insights into current drivers of mpox outbreaks in the country, emphasizing the need for improved surveillance, understanding mechanisms behind viral emergence in rural and urban areas, and regional collaboration. The IPB research team will continue to use the now established surveillance strategy for routine long-term mpox monitoring in close collaboration with national authorities and HIOH’s local core partner, the World Wide Fund for Nature in Central African Republic.

The study was supported by the Pasteur-Institut in Bangui, Africa CDC, AFROSCREEN, WHO, the Helmholtz Institute for One Health and the Deutsche Forschungsgemeinschaft.

Original publication

Christian Noël Malaka, Livia Victoria Patrono, Thais Berenger Tombolomako, Ella Farra, Ornella Sibiro, Sandra Garba-Ouangolé, Benjamin Selekon, Cyprien Gildas Lemon, Festus Mbrenga, Aboubacar Soumah, Jenny Lorke, Ariane Düx, Julien Honorat Semdouto, Frédéric Stéphane Singa Niatou, Jephté Kaleb Kandou, Mbaïlao Raphaël, Jean Méthode Moyen, Ernest Kalthan, Edith Sako, Aubin Ngbeadego-Soukoudoupou, Odilon Auguste Kpahina, Philippe Lemey, Áine O’Toole, Andrew Rambaut, Pierre Somse, Sébastien Calvignac-Spencer, Emmanuel Nakoune, Fabian Hubertus Leendertz, Yap Boum. Genomic epidemiology of clade Ia monkeypox viruses circulating in the Central African Republic in 2022–24: a retrospective cross-sectional study. The Lancet Microbe (2025). DOI: 10.1016/j.lanmic.2025.101173.

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