According to a new study by the Imperial College London and the World Health Organisation (WHO), East African countries, including Ethiopia and Somalia, will face an estimated 25% increase in deaths from yellow fever by 2050 because of the changing temperature and the frequent occurrence of rainfalls.
West African countries currently have the largest yellow fever disease burden on the continent. The new findings, however, indicates a shift in this burden to regions outside West Africa. According to projections estimated by the study, the Central African Republic is most likely to see an increase in transmission. Yellow fever is currently responsible for causing 78,000 deaths in Africa every year. Despite an existing yellow fever vaccine, the disease is endemic in 34 countries in Sub-Saharan Africa, with serious outbreaks occurring in recent years.
The virus can be transmitted by several mosquito species or vectors, but the main vector in serious urban outbreaks is the mosquito species Aedes aegypti. The analysis also notes warmer temperatures can help mosquitos emerge and mature faster, increasing their population. Rainfall can also increase mosquito breeding by providing the ideal climate and ponds for them to lay eggs in.
The team modelled changes in temperature and rainfall across African countries. By 2050, the modelling showed that deaths could increase by around 11% for the best-case scenario and up to 25% for the worst-case scenario. By 2070, these figures were projected to be 10% and 40% respectively.
Lead author of the study Dr Katy Gaythorpe, research lead for the Vaccine Impact Modelling Consortium from the School of Public Health at Imperial College, said: “We could see yellow fever expanding into new areas and worsening in regions where it is already causing major outbreaks. To prevent this resulting in thousands of more deaths, a programme of surveillance and appropriate mosquito control and vaccination will need to be sustained.”
