This disease is spread by infected mosquitoes normally from sunrise to sunset and is endemic in parts of Sub-Saharan Africa and South America. During outbreaks it has up to a 50% mortality rate and therefore the World Health Organisation (W.H.O.) recommends vaccination against Yellow Fever if travelling to affected regions. In addition, some countries require a certificate proving vaccination before allowing entry. A single vaccine certificate lasts for ten years and is available only at registered Yellow Fever Vaccination Centres. Insect bite avoidance using repellents, mosquito nets and covering up in clothing treated with Bugproof Clothing Treatment is essential.