The link between the Zika virus and the development of microcephaly, in which babies are born with abnormally small heads, is still not yet proven, but the evidence is steadily building up. Now, for the first time, researchers have found the complete genome of the Zika virus in the brain of a fetus with microcephaly. The virus was found in what the scientists describe as an “extremely abnormal brain,” but not in any other organs of the aborted fetus, suggesting that it preferentially infects the brain.

While the virus has been known since 1947 when it was first identified in Uganda, it has since spread around the world. After making it out of West Africa, it emerged in Asia, Micronesia, and the Philippines before finally arriving in South America, where it has been linked to a spate of babies born with microcephaly. Why it has suddenly emerged with such a devastating effect, particularly in Brazil, is still unknown, with researchers scrambling for answers and a much-needed vaccine.

^{Officials across South America are now embarking on a large-scale mission to control the mosquitoes that spread Zika. Conred Guatemala/Flickr CC BY-NC-ND 2.0}

Reports have also been trickling in of more and more people outside of South America being diagnosed with the virus. While active transmission has so far been mainly limited to the tropics, many people returning from these countries have brought the virus back with them. In the U.S., there have been 35 confirmed cases mostly associated with travel, while Australia reported their first case of Zika in a pregnant woman this week. It is important to stress that the risk of disease transmission in these countries is still close to zero because it is predominantly spread by only one species of mosquito, which is only found in certain areas.

In what is seemingly a trend, it appears that Zika might have been spreading around the world undetected for some time, before the public health emergency was declared by the World Health Organization. In the U.K., for example, seven people have been diagnosed with Zika during the last three years, but four of those cases were only discovered since January. A similar situation has been seen in Australia, with one person reportedly contracting the virus in December last year, but only testing positive last week. Officials think that with the outbreak in South America gaining so much attention, more people are now getting tested and finding they unknowingly have the virus.  

In an effort to speed up research into the virus, and encourage the sharing of knowledge, Nature has announced it will make all papers relating to the Zika virus free to access until further notice. The publishing group say that they have been spurred to make the decision as a result of both the Ebola outbreak in 2014 and the ongoing Zika epidemic. They note that in the context of public health emergencies, the sharing of all information allows all relevant parties to make the most informed decisions. 

While no travel bans have been issued, public health officials are still calling on people to assess their risks before traveling to countries where transmission of the virus by mosquitoes has been confirmed. This warning currently only applies to pregnant women, to try and prevent them from infecting their unborn child. There is, however, some concern about the potential that the virus could be sexually transmitted, and so men are advised to use condoms for at least four weeks after travel to infected countries.