Zika virus 101

Let's talk outbreak. Nope, not the movie about Ebola, but a close cousin. Well, "close" as in, they're both about a virus originally found in Africa and that's about it. So, third cousin twice removed?

Anyway, I'm talking about the Zika virus outbreak happening in South America right now, specifically in Brazil. Until recently, this virus has been fairly localized to Africa and Asia, so North America hasn't paid much attention. It's not deadly and the illness is pretty mild, with only an estimated 20% of infected people even showing symptoms. Plus, its symptoms are very common and could easily be mistaken for a bunch of different viruses: fever, rash, joint pain, and sometimes headache. The one notable thing to watch for is conjunctivitis, or red eyes, which is more common with Zika than other bugs.

If you're healthy and get bit by a mosquito carrying Zika, a couple of weeks later you have a weird flu for 2-7 days, then you get better and carry on with life. In fact, the first outbreak outside of Africa and Asia occured on Yap Island in the South Pacific in 2007. No one died or was even hospitalized, despite an estimated 73% of the population being infected. So in general, not a particularly note worthy infection, just kinda annoying.

The problem is, and the main reason this virus is in the media, if you happen to be a pregnant woman who catches the Zika virus. And here's where things start to get serious, so don't expect as many jokes as normal. Early in 2016, doctors in Brazil started noticing what looked like an increase in the amount of babies born with abnormally small heads and severe brain defects; microcephaly.

So of course everyone went a little crazy. Wild theories took hold, with the most talked about pointing fingers at the larvide pyriproxyfen and everyone's favourite "evil" corporation, Monsanto (which doesn't even produce the chemical in question). Just to ease your fears, that theory has been thoroughly debunked. There are several regions of Brazil that don't use the larvicide and are still reporting increased cases, while one of the hardest hit cities (Recife) doesn't even use that pesticide, at least within the municipal water. Plus, while the chemical affects insect development, humans don't even make the proteins that pyriroxyfen targets.

Alternatively, many doctors and scientists in Brazil suspected the Zika virus. This relatively innocuous bug had appeared in Brazil in May 2015, around 9 months before so many babies were born with microcephaly. Yes, just a correlation which we know can be coincidence like with the larvicide, but a decent theory that was worth investigating.

Yet I remained skeptical; it's very deeply ingrained in my psyche from years of science. The link between Zika virus and microcephaly just seemed too weak, and there were reports that the number of microcephaly cases were being over-reported. So I have something to admit: I was totally wrong. If I had written this post about the Brazilian microcephaly epidemic a month ago (which I started to, but didn't finish it), there would have been a lot of "it's possible, but not necessarily true" statements being used.

The thing is, it's really, really hard to get conclusive evidence for serious diseases, especially when it involves babies. Nobody's going to let you experiment on their newborns or fetuses, And it's next to impossible to get that sort of data in a rush. Producing diagnostic tests, finding hard data and developing an animal model can take quite a long time. The best we can do is a scientific consensus. And the more I read about this unfortunate epidemic, the more I'm convinced that mosquitoes are the devil.

No wait, I mean I'm convinced that Zika infection in early pregnancy can lead to microcephaly. A virus leading to birth defects certainly isn't unheard of. Rubella (German measles), toxoplasmosis (from cats, which is why pregnant women shouldn't change litter boxes) and cytomegalovirus (I have nothing to add here but enjoy consistency) can all cause birth issues including microcephaly.

So let's talk scientific consensus. What in the world does that mean? I figured it had guidelines (scientists and government agencies generally like rules), but I only looked into what they were recently. However, this post is long enough already and the consensus criteria is going to be very wordy, so I'll put it up now as a separate post.