Tracking the evolution and transmission of yellow fever

A pioneering Oxford University research collaboration into yellow fever virus (YFV) has shed new light on the exceptional recent outbreak in Brazil and how the virus spreads. The findings have implications for monitoring viral transmission and could potentially contribute to a strategy for eliminating YFV worldwide. Published in Science , the international collaboration coordinated by scientists from Oxford University and FIOCRUZ Rio de Janeiro, uses modern genomic and epidemiology techniques to investigate in detail the mode of transmission of South America's largest yellow fever virus outbreak in recent history. Techniques such as portable DNA sequencing and computational analysis allowed the team to understand the virus's genetic make-up and analyse the age, sex and spatial distribution of human cases. Yellow fever virus is transmitted by mosquitoes in one of two ways, via sylvatic (forest) or urban (city) transmission. Most recent cases of YFV in Brazil have been traced back to forest dwelling primates and mosquitos - a pattern characteristic of sylvatic transmission. But historical outbreaks in Brazil, and a recent outbreak of the virus in Angola, Africa, arose from urban transmission - a mode of infection that could cause a great number infections in cities.