CDC Says Zika Virus Could Have Greater Impact on U.S. Than Originally ThoughtPosted on April 14, 2016 The CDC is growing increasingly concerned about the Zika virus which has been spreading in Mexico, South America and the Caribbean. The virus is spread by mosquitoes. It has been linked to severe birth defects. There is no cure for the virus. A transmission electron micrograph of the Zika virus is pictured above. The virus can spread to humans when they are bitten by an infected Aedes species mosquito. There have also been reports of the virus spreading during sex with an infected person. Most people have only mild symptoms such as fever, rash, red eyes and joint pain. In more serious but rare cases it can cause Guillain-Barre syndrome. The bigger concern is for pregnant women. Zika infection during pregnancy has been linked to infant microcephaly where a baby is born with a smaller head than normal. There has been an increase in the number of babies born with microcephaly in Brazil where there has been a large Zika virus outbreak. Experts are now convinced about a connection between Zika and microcephaly. The image below shows a baby with microcephaly compared to a baby with a normal head size. In the U.S. there have been a total of 358 cases. All of the cases are in people known to have traveled to a country where the Zika virus is actively spreading. None of the cases have been locally acquired in the U.S. so far but there is concern this will happen because the mosquito capable of carrying Zika is present in many states. A map here shows the potential range of the mosquitoes capable of carrying Zika, dengue and other diseases. The CDC says the virus is "scarier" than originally thought. BBC News reports that the CDC is concerned the mosquitoes carrying the virus could spread to more U.S. states than originally thought. Dr Anne Schuchat, Principal Deputy Director for the CDC, says they have assumed a risk to pregnant women since January of this year. They now have conclusive evidence about the link between Zika and microcephaly. Dr. Schuchat is also recommending couples use condoms or avoid sex if a partner has been to a country where there is active Zika virus transmission. She also says they are still seeking answers about the virus and the risk to pregnant women. Take a look: