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Yellow fever: outbreaks in East, West and Central Africa

Outbreaks reported in areas across East, West and Central Africa at risk of yellow fever transmission

• This updates the news item of 15 September 2022

Yellow fever (YF) is a viral haemorrhagic disease, transmitted to monkeys and humans by forest or urban dwelling mosquitoes. There is a risk of YF in some parts of tropical and subtropical regions of Africa. Between 1 January 2021 and 7 December 2022, a total of 13 African countries reported either confirmed or probable cases of YF. A total of 203 confirmed and 252 probable YF cases, with 40 deaths were reported to the World Health Organization (WHO). Despite mosquito control measures and local mass vaccination campaigns, the risk remains in many of these countries [1].

Cases continue to be reported in Nigeria, which has, since September 2017, experienced a re-emergence of YF, with outbreaks reported across all 37 Nigerian states. Local mass vaccination campaigns continue across many states [1].

Ghana reported an outbreak that started in October 2021 [2], with cases and deaths reported in 13 regions [2, 3]. This outbreak started in largely unvaccinated nomadic people who moved from Nigeria into a forest in the Savannah region of north-west Ghana [2, 3] which is also a popular destination for tourists.

Outbreaks or confirmed cases have also been reported in Cameroon, Central African Republic, Chad, Côte d'Ivoire, Democratic Republic of the Congo, Gabon (an isolated confirmed case in 2021), Kenya, Niger, Republic of the Congo, Sierra Leone and Uganda [1].

The outbreak in Kenya is the first report of locally acquired confirmed YF cases since 1995 [4]. Cases in Kenya have also been reported in a province outside of the recognised YF transmission area [5].

In response to YF outbreaks, public health measures, including risk communication to raise awareness, catch-up vaccination programmes, enhanced surveillance and tightening of border controls to prevent international spread are usually implemented [6].

The overall burden of YF in Africa is thought to be underestimated. This is due to a combination of factors, including low vaccination rates, a lack of comprehensive surveillance and difficulties in confirming the disease in some regions. Laboratory diagnosis exists, but availability and lack of diagnostic capacity are major challenges for some African countries [7].

A comprehensive global strategy to eliminate YF epidemics (EYE) has been developed by global partners, with the aims to protect at risk populations, prevent international spread and contain outbreaks quickly [8].

The WHO recommends YF vaccination for all travellers aged nine months and older visiting areas with risk of YF transmission [9], unless the vaccine is contraindicated for medical reasons.

Travellers should be aware that if a country does not have a requirement for an International Certificate of Vaccination or Prophylaxis (ICVP) for YF that does not necessarily mean that there is no risk of YF in that country. Specific YF information on risk, vaccine recommendations and certificate requirements are available on the Country Information pages.

TravelHealthPro does not report all individual YF cases reported in endemic countries on the Outbreak Surveillance but does report outbreaks and unusual YF activity.

All travellers to Africa should follow mosquito bite avoidance guidance.

Resources

• UK Health Security Agency & NaTHNaC: Mosquito bite avoidance – advice for travellers
• Yellow fever: Information for travellers leaflet
• Yellow fever pre-vaccination checklist
• Yellow fever vaccine recommendation maps