The More We Know About the Zika Virus, the More Confusing It Gets

MEDICAL MYSTERY02.02.16 12:20 PM ET

The More We Know About the Zika Virus, the More Confusing It Gets
Does it cause birth defects? Can it be sexually transmitted? Why new outbreaks usually stump the experts.

By: Kent Sepkowitz

The deepening Zika virus outbreak has entered a too-familiar phase: total confusion. Once a simple (though hair-raising) story about a mosquito, a virus, and a devastating birth defect, Zika now is a chaotic mess of conflicting data. As new facts and fears have piled up, it has become just about impossible to tell exactly which way is up.

Two new events have added to the din. First, the World Health Organization held a press conference yesterday to proclaim the most alarming birth defect—microcephaly—to be an official global disaster, or in WHO-speak, a “Public Health Emergency of International Concern.” This designation frees up resources and focuses appropriate attention on the problem.

What the WHO did not proclaim was a “Zika virus” crisis. That’s because Zika infection among those not pregnant is a nuisance, albeit with a small risk of Guillain-Barre paralysis—but that’s all. The public health problem, rather, is the apparent risk to a fetus of maternal infection. Yet the data still does not crisply establish a cause and effect relationship between the virus and microcephaly.

This lawyerly sidestep allows the WHO to focus on the disease and not the putative cause, thereby avoiding (they hope) future criticism that they waffled too long.

Which is fine—public health is hard, especially when the economic future of an entire country or region hangs in the balance. And the reason for their bureaucratic caution was brought home by the second noteworthy Zika event of the week (and it’s only Tuesday!)

In Scientific American, a report of Zika in Colombia, which shares a border with Brazil, describes over 2,000 cases of Zika in pregnant women but no microcephaly in the offspring. Confused yet?

The preliminary information from Colombia flies in the face of a re-look at a previous Zika outbreak from 2013 that affected 28,000 people in French Polynesia. Initial descriptions did not identify microcephaly but, according to WHO comments yesterday, more recent scrutiny of the aftermath of the epidemic has demonstrated an increase in this birth defect similar to what is being seen in Brazil.