On February 1, 2016, the World Health Organization (WHO) declared the growing outbreak of the Zika virus in the Americas to be a Public Health Emergency of international concern. What is the virus, and why is it so important for the international community to bring it under control? - Written by Ian Portelli, Carly Esteves, Jaffer Naqvi, Shannon Rafferty, Kristina Dolan, Gabrielle O'Donoghue, Dr Reinaldo Acosta and Christian Lucky. (Volume 11, Issue 4)