Predicting intensities of Zika infection and microcephaly using transmission intensities of other arboviruses

The World Health Organization has declared Zika Virus a Public Health Emergency of International Concern due to the virus' emergence in multiple countries globally and the possible association of Zika virus with microcephaly and neurological disorders. There is a clear need to identify risk factors associated with Zika infection and microcephaly in order to target surveillance, testing and intervention efforts. Here, we show that there is a strong correlation between the incidence of Zika in Colombian departments and the force of infection (but not the crude incidence) of dengue, a virus transmitted by the same mosquito species, Aedes aegypti (R2 = 0.41, p<0.001). Furthermore, we show that there is also a strong correlation between the incidence of microcephaly in Brazilian states and the force of infection of dengue (R2 = 0.36, p<0.001). Because dengue, Zika and Chikungunya are transmitted by the same vector, these associations provide further support to the supposition that Zika virus infection during pregnancy causes microcephaly. In addition, they provide an opportunity to project the expected incidence of microcephaly in multiple dengue endemic locations across Colombia and the American continent. Detailed knowledge of dengue transmission should be use to target efforts against Zika and other flaviviruses.