The persistence of Ebola virus transmission in Sierra Leone, Liberia and Guinea took everyone by surprise. Previous outbreaks had lasted only weeks. The World Health Organisation’s response to Zika in South America has been significantly influenced by criticisms of the speed of its response to the events in West Africa. But a recent note in the Morbidity and Mortality Weekly Report from the US Centers for Communicable Disease Control and Prevention is a reminder that the absence of virologists, public health doctors and nurses wasn’t the only reason for the size of the Ebola epidemic.