...Ebola has contributed to the negative psychology that has sent stock prices reeling this month. Need proof? The chart below shows how the VIX volatility index has spiked since the summer. At the same time, the number of searches on Bloomberg terminals (a key resource for many investors) for news related to the Ebola outbreak has also skyrocketed. Of course, correlation doesn't imply causality, but it's worth noting. Ebola is "not by itself directly responsible for everything, but it's obviously making things work," said Dan Greenhaus, chief global strategist at BTIG.

http://money.cnn.com/2014/10/20/investing/ebola-stocks-markets-volatility-wall-street/