The effect of climate change on Yellow Fever disease burden in Africa

Abstract Yellow Fever (YF) is an arbovirus capable of causing haemorrhagic fever which is endemic in tropical regions of Africa and South America. In recent years, it has resurged – leading to large outbreaks and expanding its endemic zone, the causes of which are unknown. In Africa, the disease is currently considered endemic in 34 countries where it is estimated to cause 78,000 deaths a year. As the mosquito vectors of YF sensitive to environmental conditions, climate change may have substantial effects on the transmission of YF. Here we present the first analysis of the potential impact of climate change on YF transmission and disease burden. We extend an existing model of YF transmission in Africa to account for rainfall and a temperature suitability index. From this, we project transmission intensity across the African endemic region in the context of four climate change scenarios (representative concentration pathways (RCPs) 2.6, 4.5, 6.0 and 8.5). We use these transmission projections to assess the change from current to future disease burden in 2050 and 2070 for each emission scenario. We find that disease burden changes heterogeneously with temperature and rainfall across the region. In RCP 2.6, we find a 93.0% [95% CI 92.7, 93.2%] chance that deaths will increase in 2050. We find that the annual expected number of deaths may increase by between 10.8% [95% CrI -2.4, 37.9%] for RCP 2.6 and 24.9% [95% CrI -2.2, 88.3%] for RCP 8.5 in 2050, with the most notable changes occurring in East and Central Africa. Changes in temperature and rainfall will affect the transmission dynamics of YF. Such a change in epidemiology will complicate future control efforts. As such, we may need to consider the effect of changing climactic variables on future intervention strategies.