29 Dec 2021

Yellow fever: outbreaks in West and Central Africa

Outbreaks reported in areas across West and Central Africa at risk of yellow fever transmission Yellow fever: outbreaks in West and Central Africa
  • This updates the news item of 17 December 2021

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 West and Central Africa; nine countries in this region reported human laboratory confirmed cases of YF during 2021 [1]. Between 1 January and 20 December, 300 probable and 88 laboratory confirmed cases were recorded [1]. The World Health Organization (WHO) state the overall YF vaccination coverage in this area is not sufficient to provide herd immunity and prevent outbreaks [1]. According to the WHO, the upward trend of cases and outbreaks, is indication of ongoing intense YF virus transmission in the region and represents a persistent and growing risk to all unvaccinated people living or visiting YF risk countries [1].

Since September 2017, Nigeria has experienced a re-emergence of YF, with outbreaks reported across the country. Between 1 January and 30 September 2021, a total of 1,518 suspected cases have been reported in 428 Local Government Areas (LGAs) across all 37 Nigerian states including the Federal Capital Territory [2].

Ghana is reporting an outbreak that started in October 2021, with cases and deaths reported in four regions (Savannah, Upper West, Bono and Oti). Most cases in this outbreak occurred in largely unvaccinated nomadic populations moving from Nigeria into a forest reserve in Savannah region, north-west Ghana, also a popular destination for tourists. Several factors, including a favourable ecosystem in the region and mobile unvaccinated populations, including tourists, may increase the potential for the spread of YF from this region to neighbouring countries (i.e. Côte d'Ivoire and Burkina Faso) and is of concern [3].

Outbreaks / confirmed cases have also been reported in Cameroon, Chad, Central African Republic, Côte d'Ivoire, Democratic Republic of Congo, Niger and Republic of Congo during 2021 [1].

In response to 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 [4].

The overall burden of yellow fever in Africa is thought to be underestimated. This is due to combination of factors, including low vaccination rates, a lack of comprehensive surveillance and difficulties in confirming yellow fever disease in some regions. Laboratory diagnosis exists, but availability and lack of diagnostic capacity are major challenges for some African countries [5].

A comprehensive global strategy to eliminate yellow fever epidemics (EYE) has been developed by global partners, with the aims to protect at risk populations, prevent international spread and contain outbreaks quickly [6].

The World Health Organization recommends yellow fever vaccination for all travellers aged nine months and older visiting areas with risk of yellow fever transmission [7], 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 yellow fever that does not necessarily mean that there is no risk of yellow fever in that country. Specific yellow fever information on risk, vaccine recommendations and certificate requirements are available on TravelHealthPro Country Information pages.

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

All travellers to Africa should follow mosquito bite avoidance guidance.


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