The mosquito-borne Zika virus is drawing global attention. Earlier today, the head of the World Health Organization said Zika is spreading explosively." Brazil has reported more than 4,000 cases of babies born recently with microcephaly, a brain condition characterized by an abnormally small head that can lead to developmental issues or even death. That number compares with fewer than 150 cases in the country for all of 2014. The virus is mainly a health concern for women who are pregnant and it does not have long-lasting effects on most people. The virus is primarily transmitted through the Aedes aegypti mosquito. So far there is limited evidence on whether Zika can be transferred from mother to child. But because of the rash of microcephaly cases in Brazil, which spiked after the first confirmed case of Zika, this maternal link is "strongly suspected" and being closely studied. Only one in five of those infected with Zika show symptoms, which develop up to one week after being bitten. Most symptoms are mild, and ... can be easily treated with rest and plenty of fluids. Dr. Sumon Chakrabarti told CBC News, "the one thing to make very clear is that Zika, once it's out of your body, it's gone. It's not something like Hepatitis B or HIV that can stay in your body forever. "Overall, Zika is a very mild illness apart from what we think might be happening in pregnant women."