Zika: Zika in Colombia: Characterisation of exposure and epidemiology in a flavivirus endemic setting

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Following the large-scale epidemic in Brazil in 2015, Zika continues to spread across Latin America. However, our understanding of the transmission dynamics and epidemiology of this new threat remains poor. In particular we have limited information on the extent of population exposure: many infections remain asymptomatic or cause mild disease which can easily be misdiagnosed, while antibody cross-reactivity between flaviviruses make the results of serological testing difficult to interpret given much of the region is endemic for dengue.
With 31.000 cases reported by Feb 2016 (4 months after the first case was diagnosed), Colombia is currently the second most affected country. Our proposal seeks to characterise the epidemiology of Zika in Colombia and establish a Colombia-focussed research network of partners with complementary expertise.
We will install state-of-the-art serological testing facilities in Colombia and conduct serological surveys in four cities with varying levels of dengue transmission intensity and reported Zika case incidence. We will develop statistical models to analyse age-stratified flavivirus seroprevalence data in a context where multiple flaviviruses co-circulate. These will allow us to characterise the force of infection, attack rate and transmissibility of Zika. We will then use these estimates to assess current levels of herd immunity to Zika thus predict possible future attack rates. Finally, we will estimate the proportion of infections which are asymptomatic and the per-infection risk of severe outcomes (e.g. microcephaly).
The outputs from this project will be of immediate value in enabling improved situational awareness and in informing the development of evidence-based control strategies.