With every disease outbreak, researchers try to figure out how far — and how fast — a virus is likely to spread through a population.  To do that, they use a number called an “R naught,” or R0. Most simply, the figure refers to how many other people one sick person is likely to infect on average in a group that’s susceptible to the disease. Here’s what we know so far about the Ro of Zika and Ebola.

Read more at Zika and Ebola, explained by their outbreak potential – Vox

Learn more about the World Health Organization’s work on the Ebola and Zika virus  Act Now