AsianScientist (Feb. 22, 2016) – Like most people who study mosquito-borne diseases, I’ve been following the Zika outbreak in Latin America closely. In fact, it’s been almost impossible not to, when news and social media feeds are dominated by reports on the virus and its link to microcephaly.
In scientific circles, the virus has been catapulted from obscurity into the spotlight. A quick look on PubMed—a popular search engine for academic articles—turns up a mere 225 reports on Zika, despite it having been isolated in 1947. For comparison, there are around 15,000 on dengue and 2,600 on chikungunya.
But this number looks set to change: more than half the body of literature on Zika—around 120 articles—was published within the last year or so, and 70 of these in the first two months of 2016 alone.
The case of Zika and microcephaly
The link between Zika and the spike in microcephaly cases in Brazil has not been proven, and doing so is likely to take months at the very least. But enough circumstantial evidence has accumulated for the World Health Organization to say that it is now considering Zika “guilty until proven innocent” (legal rights for viruses are clearly non-existent).
Researchers have, for example, been able to recover the entire Zika virus genome (about 11,000 bases long) from the brain tissue of an aborted fetus with microcephaly; using electron microscopy, they could also see virus particles in the brain.
Importantly, they looked for but did not detect Zika-related viruses such as dengue and yellow fever, or other viruses that are known to cause microcephaly, including rubella and cytomegalovirus.
Further, they were not able to detect Zika in fetal organs other than the brain, suggesting that the virus is extremely neurotropic—that is, having the ability to home in on the brain and nervous system.
This one case report doesn’t prove anything, but it does associate the presence of the virus with microcephaly, and is strong evidence that it can be transmitted across the placenta. Case-control studies (comparing pregnant women with and without Zika), now underway in Brazil and Colombia, will be essential for establishing causation.
Developments in Colombia will be especially telling—the Zika outbreak there began several months after Brazil’s, such that the first babies exposed to the virus will start arriving around June this year.
The responsibility of the media
As someone who dabbles in science communication, it’s also been fascinating to observe media coverage of the outbreak. Zika is clearly an important, multi-faceted global health problem that needs to be reported on.
But while it has all the right ingredients of a captivating story—exotic virus; a birth defect of a tragic, graphic nature; issues surrounding women’s reproductive rights; the uncertainty of a constantly evolving situation—these same elements also make it easy for misinformation to take hold.
For instance, several news sites recently picked up a report from a group of doctors that alleged that microcephaly was caused not by Zika, but by exposure to a larvicide used in Brazil to control mosquito populations. From there, the story, for lack of a better term, went viral.
Common sense eventually prevailed, and refutations by experts of the report’s numerous inaccuracies have since been widely reported. But some damage may already have been done—at least one state in Brazil has suspended the use of the larvicide, a decision which may be bad news for mosquito control efforts.
Honing your bullshit-o-meter
As users of social media, we aren’t completely devoid of responsibility, either. Not everyone is George Takei (who shared the larvicide story with his 9.5 million Facebook followers), but I’m guessing that for the average person, clicking “share” on an article is likely to point several hundred people in its direction.
It wouldn’t hurt to exercise some basic BS detection—a group that calls itself “Doctors in the Crop-Sprayed Villages” is unlikely to be the most objective about larvicide use, for example, and neither are sites called EcoWatch and GMWatch.
Over the past decade or so, we’ve gained some ground in the fight against mosquito-borne diseases. There is finally a licensed dengue vaccine, and novel interventions targeting the vector—in particular the release of Wolbachia-infected and sterile male mosquitoes—are in field trials, with promising results.
Zika, however, is a reminder of the many surprises these viruses can still spring on us. Even so, while the link to microcephaly is new, the virus hasn’t come completely out of left field—Micronesia, French Polynesia, and Easter Island have seen major epidemics within the past few years. The developed world, as usual, just wasn’t paying attention.
Zika will certainly provide a boost to mosquito control efforts, but—remembering how quickly Ebola dropped out of the news even as the epidemic raged on in West Africa—will this last long enough to prevent future outbreaks?
This article is from a monthly column called The Bug Report. Click here to see the other articles in this series.
Copyright: Asian Scientist Magazine; Photo: Shutterstock.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.