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Five things to know about Zika

Aedes mosquito

As rumors about Zika continue to circulate, scientists are learning as much as they can about the mosquito-borne virus.

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The mysteries of the Zika virus are slowly but surely succumbing to the scientific method. Last week, scientists revealed the virus’ structure, gleaned further insight into its ties to the birth defect microcephaly and found out just how little some people seem to know about Zika. Public health researchers at Harvard University released the results of a poll related to Zika awareness on March 29, and lots of respondents flunked. In a survey of 1,275 adults, 23 percent were unaware of Zika’s association with microcephaly and 42 percent did not know the virus could be transmitted sexually.

The survey highlights some general confusion about the facts of Zika, and the latest new tidbits show how quickly researchers are learning new things about this virus. So, let’s take a look at what people are saying about Zika and set the record straight .

Yes, in the case of microcephaly, Zika looks very, very guilty. No, pesticides and vaccines do not cause microcephaly. 

A few different things, including viruses, can cause microcephaly, a birth defect in which babies have abnormally small heads and brain damage, as Meghan Rosen notes in the April 2 Science News. At the moment, there’s no smoking gun to convict Zika as the perpetrator behind Brazil’s uptick in microcephaly, but it’s not looking good for the virus. In Brazil, more microcephaly cases have appeared in places with more Zika cases. Zika has also been detected in the amniotic fluid, placenta and brain tissue of fetuses with microcephaly. It attacks specific cells related to fetal development. Zika infection during pregnancy has been linked to miscarriages and placental problems, plus other neurological conditions, including the rare autoimmune disease Guillain-Barré syndrome.

WHO officials noted in their March 31 situation report: “Based on observational, cohort and case-control studies there is strong scientific consensus that Zika virus is a cause of [Guillain-Barré syndrome], microcephaly and other neurological disorders.”

The evidence against other suspects is much less compelling. Still, a report by a group in Argentina calling themselves “Physicians Against Fumigated Towns” sent the Internet into a tizzy in February with the claim that the larvicide pyriproxyfen, not Zika, was to blame for microcephaly cases. The WHO has since reviewed toxicology studies and widespread use of the pesticide and found no evidence that the chemical interfered with human pregnancy or development. Similar rumors that vaccines or genetically modified mosquitoes caused Brazil’s microcephaly uptick simply lack any evidence, the WHO says.

Yes, you can get Zika by having sex with an infected person.

Though Aedes mosquitoes serve as the primary vector for Zika, researchers have had suspicions for a while that Zika could be sexually transmitted. In 2008, a U.S. researcher developed Zika infection symptoms after returning home from studying mosquitoes in Senegal and transmitted the virus to his wife through sex. This was the first documented sexually transmitted case of Zika.

Since then, more sexually transmitted cases have emerged in the U.S., as well as in Italy, France, Argentina, Chile and New Zealand. Thus far, only men have transmitted the virus, and whether women can also transmit the virus to their sexual partners is unknown. Researchers suspect that the virus may linger longer in semen than in blood — another potential source of transmission currently being investigated. (On March 30, the U.S. Food and Drug Administration approved a screening test for Zika in blood donatons.) To prevent the spread of Zika between sexual partners, the CDC recommends the usual precautions.

No, there’s no vaccine for Zika, but people are working on it.

There is currently no vaccine against Zika, and vaccines against other viruses from the same family, like yellow fever, do not offer protection against Zika. That said, concern over Zika’s link to neurological disorders and growing case counts in the Americas has jump-started efforts to develop a vaccine. The idea of a chimeric vaccine that could combat Zika and other related viruses like dengue is an attractive research prospect. On March 31, a team reported the virus’ structure in Science, providing potential clues for vaccine development.

Sometimes Zika symptoms are obvious. Sometimes they’re not.

Only 20 percent of the people who get Zika actually notice symptoms. When they do, those symptoms include fever, rash, sore joints, pink eye and muscle pain. Sometimes Zika cases look a lot like dengue and chikungunya — meaning there’s potential for misdiagnosis.

No, sterilized mosquitoes do not increase the spread of Zika. In fact, they could help fight it.

There’s no evidence that sterilized mosquitoes aid and abet the spread of the virus. Some researchers would actually argue that they are our best chance of stopping it, Susan Milius notes in the April 2 Science News. Sterilization, by zapping males with radiation or genetically tweaking them, could reduce and theoretically wipe out a mosquito population. Meanwhile, gene drives likes CRISPR/Cas9 seem poised to make genetic sterilization methods a lot easier, too. Infecting mosquitoes with Wolbachia bacteria also cuts bloodsucker populations. If all else fails, El Salvador is using the tried and true method of deploying fish to eat all the larvae in mosquito breeding ponds. It goes without saying, but none of these control methods actually aid the spread of Zika.

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