• What is Zika? Is it a new virus?
Zika is actually an old virus ” it's only recently that health experts have been seriously worried. It was first discovered in 1947 when it isolated from monkeys in the Zika forest in Uganda. And for decades thereafter, it barely bothered humans.
Prior to 2007, there were only 14 documented Zika cases. But then the first big outbreak erupted on Yap island in Micronesia, with 49 confirmed cases. And from there, the virus was on the move.
Soon cases popped up in other Pacific Islands, including a large outbreak in 2013-'14 in French Polynesia (388 cases). By May 2015, health officials had detected the virus in Brazil ” possibly arriving with a traveler to the World Cup. Within a year, more than a million people in Brazil had been affected, as mosquitoes carried it from person to person as they do diseases like malaria and yellow fever.
Zika has since spread to more than 20 countries ” mostly concentrated in Central and South America and the Caribbean ” and it's expected to go much further.
• What happens if you get Zika?
One of the things that makes Zika very difficult to track is the fact that in the vast majority of cases, it causes no symptoms at all. Most people who get infected don't even realize it ” and therefore never seek medical attention. They can, however, still transmit the disease if they are bitten by a mosquito that then bites someone else.
Meanwhile, a minority of Zika patients ” roughly 20 percent ” show relatively minor symptoms: a low-grade fever, sore body, and headache, as well as red eyes and a body rash. More rarely, this might include abdominal pain, nausea, and diarrhea. These symptoms usually appear two to 12 days after a bite and go away within a week. Severe disease requiring hospitalization is uncommon.
In both the Brazil and French Polynesia outbreaks, researchers noted that some people infected with the virus were later diagnosed with Guillain-Barré, a rare and sometimes deadly neurological condition in which people's immune systems damage their nerve cells, leading to muscle weakness and even paralysis. The symptoms can last weeks, months, or even years.
Even more worryingly, there's evidence that Zika is linked to a terrible birth defect called microcephaly, which is characterized by a shrunken head and incomplete brain development.
• What’s this about not getting pregnant?
The difficulty with Zika is that many people who get the virus are never diagnosed ” yet it might still potentially damage fetuses. This fact has put pregnant women and would-be moms in an awful bind. In some places in Latin America, women are being told to avoid having children for months or even years because of Zika. This isn't easy: In many of these countries, family planning is nonexistent, condoms are out of reach for some, and abortion is illegal.
• How exactly is Zika spread?
Zika is mainly carried by a specific type of mosquito called Aedes aegypti, which spreads the disease through bites. There's some experimental evidence suggesting the Asian tiger mosquito (Aedes albopictus) can transmit the virus, too. What makes the Aedes aegypti a unique threat is that it is remarkably effective at carrying viruses ” it's also the primary vector of the yellow fever, dengue, and chikungunya viruses.
Mosquitoes may not be the only way to spread Zika. There have been two studies in the medical literature that suggest Zika can be sexually transmitted. In one case, a man who traveled to Senegal and contracted Zika gave it to his wife through intercourse after he returned home. In another, Zika was isolated from semen. Researchers aren't sure how long Zika can remain in semen. And it's not clear how common sexual transmission actually is. Right now the evidence is pretty limited.
• Is there any vaccine or cure?
No. Until recently, Zika didn't seem to pose much of a threat to human health. So research on the virus has been extremely limited. This outbreak has spurred funding and attention on Zika science, and the WHO has called for researchers to develop a vaccine for Zika as well as better diagnostic testing to detect the virus. This, however, will likely take years.
