Scientific American: How Zika Spiraled Out of Control
“…Virologists now need to figure out which of two potential causes is responsible for the Zika explosion. One possibility is that genetic changes within the virus supercharged its ability to infect people and cause disease. The second scenario is that the change happened outside the virus: After decades of relative isolation it reached dense population areas, providing more fertile ground for its spread. … If the outbreaks are just the result of environmental changes, perhaps Zika was always capable of causing serious effects, but they were rare in small populations and only became obvious when the virus hit a lot of people…” (Maron, 5/24).