WHO logs 67 yellow fever cases across nine African countries in 2026

Yellow fever transmission continued across West Africa through 2026, and the World Health Organization's latest outbreak report, published 6 November, puts the regional toll at 67 confirmed cases and 18 deaths across nine countries between 1 January and 12 October [s1]. The most recent activity clustered in Burkina Faso, Côte d'Ivoire, Ghana and Liberia — several of them in border areas with heavy population movement [s1].

Côte d'Ivoire carried the largest and deadliest share. As of 23 September, the country had reported 30 confirmed cases and 10 deaths, a case fatality ratio of 33% [s1]. Seven of those cases were confirmed by plaque reduction neutralization testing and 23 by PCR, spread across nine districts in seven regions; Bounkani Region alone accounted for 18 of the 30 [s1]. Burkina Faso reported 15 confirmed cases and three deaths as of the week ending 23 August — a 20% case fatality ratio — while Ghana logged four PCR-confirmed cases, three of them fatal, as of 2 September [s1]. Liberia had one laboratory-confirmed case as of 23 September [s1].

The remaining cases were scattered more widely: Cameroon reported nine cases including one death, Nigeria four cases including one death, the Central African Republic two cases, and Guinea and Togo one case each, with no confirmed deaths in the last three [s1]. Country figures reflect the latest information available to WHO as of 12 October, and reporting cut-off dates differ by country, so the counts are not a single synchronized snapshot [s1].

Why the pattern worries WHO

The agency is careful to note that epidemiological links between these separate events have not been established [s1]. What connects them is geography and ecology rather than a traced chain of transmission: several affected areas sit close to international borders, with substantial population mobility and occupational exposure in or near forested areas, against a backdrop of uneven population immunity and conditions that favour mosquito vectors [s1].

On 27 October, WHO assessed the overall risk in the African Region as moderate, citing the likelihood of continued transmission, the potential for cross-border spread, existing immunity gaps, and operational constraints on outbreak control [s1]. The global risk was rated low [s1]. Several affected districts had previously identified immunity gaps — places where preventive vaccination had not been carried out, or where coverage remained insufficient despite earlier campaigns [s1]. The populations at highest risk are the unvaccinated, particularly rural and forest-edge communities, mobile and cross-border groups, and people who work in forests, farming or mining [s1].

The scenario WHO flags as most dangerous is urban. If the virus reaches a densely populated town where the Aedes aegypti mosquito is established and immunity is low, the result could be a far larger outbreak that strains response capacity [s1]. Frequent cross-border travel tied to trade, farming, livestock and mining could carry the virus between affected and neighbouring countries, WHO notes, which is why continued transmission and additional human cases in the African Region are considered likely [s1].

National authorities, WHO and partners are responding across affected and at-risk countries with enhanced surveillance and case investigation, laboratory testing and specimen referral, active case finding, risk communication and community engagement, and the planning or rollout of vaccination campaigns [s1]. WHO is also supporting member states to assess population immunity and to coordinate cross-border preparedness and information sharing — an approach aimed at the gaps the agency itself identifies as the outbreak's underlying driver [s1].

A vaccine-preventable disease

Yellow fever is an acute viral haemorrhagic disease spread by infected mosquitoes, with an incubation period of roughly three to six days [s2]. Many infections are mild or without symptoms, but about 15% of those infected progress to severe disease — recurrent high fever, jaundice, bleeding, shock and organ failure — and of those who enter that severe phase, roughly half die within seven to 10 days [s1][s2]. Early symptoms are non-specific and can resemble malaria, dengue, viral hepatitis and other haemorrhagic fevers, which complicates diagnosis [s1].

There is no specific antiviral treatment; clinical care is supportive [s2]. The decisive tool is prevention, and here the biology is favourable: a single dose of yellow fever vaccine provides lifelong protection [s2]. That is why WHO frames the outbreak primarily as a coverage problem. Its response, coordinated with national authorities and partners, centres on enhanced surveillance and case investigation, laboratory confirmation and specimen referral, risk communication, and the planning or rollout of preventive and reactive vaccination, all under the longstanding Eliminate Yellow Fever Epidemics strategy [s1]. The region, WHO notes, has real strengths to draw on — a laboratory network, reactive vaccination mechanisms, and access to the international emergency vaccine stockpile — but persistent immunity gaps, specimen-referral delays, insecurity and competing emergencies can still blunt timely detection and control [s1].

This article is informational and is not medical advice.