Efforts are now turning to preventing, and new concerns over links for paralysis-causing syndrome.
As Zika continues to spread rapidly across Latin America, a US Centers for Disease Control doctor says there "isn't any question" the virus is linked to microcephaly, a condition where a baby is born with an abnormally small head.
"The link between the Zika virus and microcephaly is extremely strong," said Dr. Lyle Petersen, the director of the division of vector-borne diseases at the CDC, during a press conference Wednesday. "There are numerous lines of evidence now that link Zika with microcephaly, so I don't think there's any question about that any longer."
That link is strong enough that Canada recently joined the list of countries urging women to delay pregnancy (in this case, only if they have travelled to a Zika-infected country). Meanwhile, Google has pledged $1 million towards Zika research, and has also updated search engine results to prioritize updated information about the virus in affected areas.
The stronger language being used by experts to describe the relationship between Zika and microcephaly is a significant shift. Officials are always cautious when early reports of a potential link between two events emerge, because until we compile more evidence, it's not always clear whether the two are actually related or just a coincidence. Gradually, evidence has been accumulating, making researchers more confident in their claims about the link between Zika and microcephaly. It's still not known exactly what the risk is, but the evidence is convincing many doctors and scientists that the two are directly connected.
What's not as clear is the link between the virus and growing reports of Guillain-Barré syndrome: a disorder which can cause temporary, months-long paralysis and weaken muscles. An increase in cases have been reported in six countries where Zika is also present, and a a Lancet study study published this week showed there was also an increase in Guillain-Barré during a Zika outbreak in French Polynesia back in 2014. But Petersen said the evidence of a link isn't as strong as with microcephaly.
"It's just because we don't have the pathological evidence [that we do with microcephaly]," Petersen explained. "But there's growing accumulation [of evidence] every day that that's the case."
Still, the evidence of a link between Zika and Guillain-Barré is growing, in much the same pattern as microcephaly, and following a similar path from "this is a notable correlation" to "there is a definite link here."
In light of this, the Pan American Health Organization hosted more than 70 scientists this week for a summit in Washington, DC, to talk about what needs to be done as we learn more about the risks associated with this previously overlooked virus. There are multiple projects currently underway to fight the spread of the Zika: developing a more efficient test for the virus, creating a vaccine, determining the exact risk of microcephaly and Guillain-Barré, and improving vector control: avoiding and killing off the mosquitoes that spread the virus.
These are all necessary actions but, with the exception of vector control, they're actions that are going to take time. Early trials for a vaccine are still months, if not years, away. Newer, quicker tests for the virus have been developed, but distributing these tests across affected countries, particularly countries with underfunded healthcare systems, is no easy task. And even though control studies on both microcephaly and Guillain-Barré have begun, results won't be available for months.
In the meantime, public health agencies, governments, and NGOs need to also focus on getting information out so people can avoid getting infected, particularly pregnant women, Petersen said. Brazil has even enlisted its army to disseminate information and destroy mosquito breeding grounds. Petersen said there are several ways to prevent the spread, from bednets, to insecticides, window and door screens, bug repellant, and even condoms—because Zika has been shown to be sexually transmitted, as well.
"All of these methods can be employed right now. We have products available that can be used," Petersen said. "We just need to figure out whether these are acceptable methods that women will actually use in their own countries."