The Zika news just keeps on coming, too fast for anyone but a truly perverse fan of epidemics (such as myself) to keep straight. So to make your life easy and my life a little less pathetic, below is a quick summary of what we know about Zika virus so far.
First and foremost is the still unsettled connection between maternal infection during early pregnancy and infant microcephaly. The facts continue to trickle in but somehow the case is not yet closed. Scientists are growing Zika virus and showing it damages fetal cells, particularly cells from the brain. They have found it in autopsies of a few babies born with devastating and fatal disease. The explosion of cases of microcephaly exactly parallels the appearance of Zika in Brazil.
Yet there remains a fly in the ointment—one that still troubles public health authorities and has provided fodder for the ever-eager conspiracy specialists who follow public tragedy like ambulance-chasing lawyers. The map of Brazil showing microcephaly cases is concentrated overwhelmingly in the eastern coast but the Zika cases (presumably pregnant women as well) are distributed pretty evenly throughout the entire country. Plus some countries with Zika and pregnant women don’t seem to be seeing cases of infant microcephaly.
There surely are many non-grassy knoll explanations. Likeliest is the simple pace that information is gathered. The area where the first cases are seen is the area that starts to look really hard for more cases and sets up infrastructure to really enumerate the problem. Places 500 miles away may be seeing the same caseload but aren’t looking as hard or recording cases as well, at least not yet. So it is quite possible that the snapshot map from last month showing the mismatch of microcephaly cases against Zika cases is simply what happens with anything new—the first place seems so crowded.
Also plausible is that the viral strain in that region of Brazil is different at a genetic level than the virus circulating elsewhere and is, for some reason, more damaging to fetal nerve cells. Maybe the bad virus is here but not there—this sort of variation in virus behavior happens is every other viral infection, so why not Zika? Or perhaps there is a genetic difference in the human populations in the eastern coast of Brazil; perhaps something in the moms’ DNA is distinct and prevents viral control.
Additional plausible theories are many—but there also is the paranoid view, ever growing, that this is a manufactured plot. That the real culprit is some chemical toxin that seeped into the water supply, Flint-style, and now is damaging fetuses in the region.
Indeed the Physicians in Crop-Sprayed Towns (a real group from Argentina) is arguing this and getting some traction on the Internet… although as with all Internet conspiracies, there is no way to know if the increasing number and type of stories is from real uptake or from someone in mom’s basement typing faster and developing more fake websites. Time will tell—or actually, given the fate of most conspiracies, there will always be a group somewhere ready to blame humans, and not mosquitos, for the mess.
A separate non-microcephaly concern is the association between Zika infection and Guillain-Barre Syndrome (GBS), a type of paralysis. GBS has been seen before with Zika and indeed with just about every infection and vaccination ever described. Right now, public health experts are struggling to establish a “normal” rate of cases for the region. In most populations, the annual rate is about 1 case per 100,000 people. For people with Zika, the case-rate is 20 per 100,000 or higher. This is bad—until one considers that the rate after many other infections, most notably Campylobacter, a GI bug that causes the runs for a few days and little else, is about 30 per 100,000, making it the most common post-infectious cause of GBS.
Therefore seeing GBS after any infection is no big surprise; what is scary is that the resources needed to manage a bad case of GBS are considerable—a month or two or three in the ICU, much of the time on a respirator, the need for close monitoring and medical support. A country like Brazil, which was wobbling financially before Zika hit, is unlikely, from a resource perspective, to be able to meet the challenge of a crush of cases. The result will be poor care not just for those with Zika but for anyone needing ICU or other types of hospital-based care.
The sexual transmission of Zika is getting most of the headlines, of course. After all, sex is sex is sex. Plus add exotic disease, exotic locale, and exotic nomenclature and bingo: a headline winner. As I previously wrote, right now this is much more about sex and not infection. Zika will not turn into an AIDS-like explosive epidemic for a simple reason: Those with Zika are sick and not in the mood tonight, dear; in contrast people with HIV have 8 to 10 years without any symptoms while still contagious, vastly increasing the likelihood of unprotected sexual contact. That said, never underestimate the ability of any sexually transmitted infection to spread and even spread uncontrollably.
Finally the Olympics—what can you say about the Olympics that hasn’t already been said: The poor athletes are screwed; Brazil is screwed; NBC is screwed. But the risk, to the participants at least, actually is quite small—the Olympics will occur long after the rainy season when mosquito populations will be less dense; no one competing in the Games is pregnant; thousands and thousands and thousands of condoms will be carpet-bombed into the Olympic Village; and one can only imagine the amount of bug-spray distributed. It is likely though that the fear factor will lead countries to stay away (I worry about visitors and TV cameramen and journalists, not the jocks) and the Olympics, much like Moscow in 1980 and LA in 1984 will be, (let’s face it, LA), a total dud.
So there you have it—all Zika all the time. Those who had hoped that the lessons learned from Ebola (and pandemic flu and SARS) would somehow simplify our path to control of Zika virus. Oh, well. The real lesson of Zika (and all the others) is that each infection and each place the infection occurs create a unique set of circumstances that cannot be anticipated. The epidemic will continue to surprise until it is over and the specimens studied and the papers written.
The only unifying theme across all epidemics is this: that covering the United States-centric view (can I travel to Brazil for Spring Break?) always misrepresents the scale of the tragedy. Which is fine, actually—all crises are local—except for the fact that the U.S. remains the one true Sugar Daddy in the world of Global Health. We have the smarts, the trained staff, the dollars, all of it—it’s a supremacy that could make even Donald Trump happy. But the U.S. public worrying locally means that the necessary dollars and workers are not yet flowing; that only occurs when the infection circulates in the U.S. and causes waves of illness, blame, and TV appearances by dour senators. That alone should be reason enough to give over our ounce of prevention right this second.