The Zika virus was first discovered in the 1940s, though most people had never heard of it until this year. That’s because for decades, Zika outbreaks were sporadic and tiny, and the disease seemed to do little harm.
That changed in 2015. A massive outbreak in Brazil — affecting more than 1 million people — has changed our view of the mosquito-borne virus. Scientists are learning that Zika may actually be a lot more dangerous than anyone thought, potentially damaging the brains of fetuses and causing incurable and lifelong health and cognitive problems. In light of this evidence, the World Health Organization declared a public health emergency on February 1.
Meanwhile, the virus has been spreading throughout the Western Hemisphere at a rapid rate, carried by a type of mosquito that feeds on and thrives alongside humans. More than 20 countries are currently battling outbreaks, and Zika is expected to reach nearly every corner of the Americas this year (save for Canada and Chile, which aren’t home to the mosquito in question). Odds are you’ll be hearing a lot more about Zika in the coming weeks and months.
1) I’d never heard of 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.
2) What happens if you get Zika?
It really depends.
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.
But that’s not the whole story. In rare occasions, Zika seems to cause really serious problems.
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. (You can read more about microcephaly in our explainer here.)
Since Zika arrived in Brazil in 2015, more than 4,000 cases of microcephaly have been reported — a twentyfold increase from previous years.
The timing appears to be no coincidence. The virus been found in the amniotic fluid of pregnant women carrying babies with the birth defect, and even in the brains of babies with microcephaly who died within 24 hours of being born.
What’s more, reanalyses of the data from previous outbreaks, such as one in the French Polynesian islands in 2013-’14, revealed a rise in birth defects following the arrival of Zika.
But this is not a closed case. Researchers are still working to confirm the link — could it be something else that’s causing the microcephaly? — and there are major questions about the frequency of the condition. As the health ministry in Brazil works to confirm the suspected cases, they’re discarding more than they’re confirming. (As of January 29, of the 4,180 reported cases, 270 have been confirmed and 462 thrown out. Only six of the confirmed cases have been linked to Zika so far.)
Still, Zika wouldn’t be the first virus to cause microcephaly. (Rubella famously caused an epidemic of birth defects before the advent of the vaccine.) And even if this turns out to be a very rare complication of Zika, the imperfect evidence alone was enough to prompt the World Health Organization to issue a rare global public health emergency declaration.
Read the full article here.
Image via www.independent.co.uk