The virus was first identified in 1947 in Ugandan monkeys and the first case of human infection was found in Nigeria, 1954. Up until recently, Zika virus wasn't considered to be a major threat and remained virtually unknown. So if it stayed that way for so long, why is it suddenly blowing up in such a dramatic way? One of the major factors is the transmission to the Americas. The Zika virus is native to Africa and has pretty much stayed there in the past. However, the local population of South America, and all of the western hemisphere, have never been exposed to it before and are what is known as "immunologically naive". This means that there is no background immunity that might help control an outbreak and so it spreads rapidly, much like the introduction of smallpox to the Americas. This combined with the massive population of Aedes mosquitoes, who are the ideal vectors for the virus, has caused infection rates to explode. Experts are now warning that it could make its way to the mediterranean within the year and anywhere with a population of Aedes mosquitoes could potentially be at risk.
