Mpox Outbreak Update 2025: Persistent Transmission in Africa and Global Travel-Linked Cases

Mpox, caused by the monkeypox virus (MPXV), continues to pose a significant global public health challenge as of May 2025. The current outbreak features a complex epidemiological landscape with sustained transmission in several African countries and travel-linked cases worldwide. Active community transmission, particularly of Clade Ib, is reported in multiple Central and East African nations, while countries outside Africa primarily document cases associated with international travel without sustained community spread.

In Africa, the Democratic Republic of the Congo (DRC) remains the epicenter, with over 21,000 cases reported since early 2024. Both Clade Ia and Ib viruses circulate within the country, with Kinshasa identified as a hotspot for sustained human-to-human transmission. The ongoing spread in urban settings reflects the virus’s evolving ability to adapt and sustain transmission beyond its traditional zoonotic origins. Weekly suspected cases in DRC remain high, though confirmed case numbers have declined recently, likely due to testing constraints rather than a true drop in infections.

Other African countries experiencing active community transmission of Clade Ib include Uganda, Rwanda, Kenya, Zambia, Republic of Congo, Tanzania, South Sudan, and Malawi. Uganda reports approximately 200 new confirmed cases weekly, with vaccination campaigns targeting key populations underway. Rwanda and Burundi show contrasting trends, with Rwanda facing ongoing transmission and vaccination efforts initiated, while Burundi’s cases have decreased significantly.

Sierra Leone is currently undergoing a rapid outbreak surge, with over 1,300 confirmed cases in early 2025 and a case fatality rate around 0.7%. Transmission there appears to be driven predominantly by sexual contact within urban populations, particularly among adults aged 25 to 39. The outbreak in Sierra Leone has challenged health systems due to limited isolation facilities and difficulties with comprehensive contact tracing, despite strong coordination and testing capabilities.

Outside Africa, most mpox cases are linked to international travel, mainly involving Clade Ib. Countries such as the United Kingdom, Germany, India, China, Belgium, Qatar, Thailand, the USA, France, UAE, Brazil, Canada, Oman, Sweden, and Switzerland report sporadic travel-related infections but no sustained community transmission. These travel-linked cases highlight the continued risk of global dissemination due to human mobility, although widespread local spread remains limited outside Africa.

The monkeypox virus consists of several distinct genetic clades with varying epidemiological characteristics. Clade Ia, historically endemic in the DRC and neighboring regions, is linked mainly to zoonotic spillover events but is now showing increased human-to-human transmission in urban centers. Clade Ib, dominant in the current outbreaks across Central and Eastern Africa, appears to transmit exclusively between humans, including through sexual contact, and has spread to nearly 30 countries globally. Clade IIa, found in some West African countries, is less well understood but seems associated with zoonotic spillovers and limited human transmission. Clade IIb is primarily responsible for the multi-country outbreaks outside Africa since 2022, affecting mainly men who have sex with men (MSM) populations, with only occasional spillover to other groups.

The ongoing transmission of multiple clades, including emerging patterns of human-to-human spread, underscores the complex nature of the outbreak. Genomic surveillance efforts, particularly in the DRC, are crucial to understanding viral evolution, transmission chains, and guiding public health strategies. Viral mutations observed in urban areas suggest adaptation to human hosts, raising concerns about sustained transmission potential.

Public health responses focus on strengthening surveillance, diagnostics, case management, infection prevention, and vaccination. Laboratory capacity remains a challenge in many African settings, leading to underreporting and delayed confirmation of cases. Rapid diagnostic tests are under evaluation to improve detection efficiency. Clinical care improvements and infection prevention measures, including hygiene and isolation practices, are emphasized to reduce healthcare-associated and community transmission.

Vaccination campaigns have accelerated in seven African countries, administering over 668,000 doses of the Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccine, with the majority deployed in the DRC. Due to limited vaccine availability, dose-sparing strategies such as single-dose regimens and intradermal fractional dosing are implemented. Prioritization targets high-risk groups, including healthcare workers, contacts of cases, sex workers, and vulnerable populations.

Global coordination efforts are guided by a strategic framework emphasizing emergency coordination, collaborative surveillance, community protection, safe and scalable care, and equitable access to countermeasures. These efforts are essential to address gaps identified in outbreak responses, improve resource mobilization, and support national health systems.

Risk assessments categorize the overall global mpox public health risk as moderate, with Clade Ib posing a higher risk due to its rapid human-to-human transmission and international spread, particularly through sexual networks. The virus is expected to continue evolving, and ongoing vigilance through genomic surveillance, operational research, and risk communication remains critical.

In summary, the mpox outbreak in 2025 is marked by persistent transmission in Central and East Africa, emerging urban spread, and travel-linked cases worldwide. Strengthened vaccination, diagnostics, clinical care, and community engagement are key pillars of the response, alongside global cooperation to ensure equitable access and effective outbreak control measures.