Zika-microcephaly link confirmed, burning questions remain

A Colombian woman waits for test results after being diagnosed with the Zika virus at the Erasmo Meoz Hospital in Cucuta, Colombia. (AP Photo/Ricardo Mazalan)

Since Brazil first reported a startling increase in the birth defect microcephaly last fall, scientists have been working around the clock to confirm the suspected link to the mosquito-borne Zika virus. According to multiple studies, researchers have so far shown that Zika infection during pregnancy appears to increase the risk for several types of birth defects and miscarriage, and scientists have located the virus in the brains of affected babies.

Although all of this evidence is circumstantial, the World Health Organization and Centers for Disease Control and Prevention have agreed that there is enough evidence to confirm the link between Zika and microcephaly.

After months of mounting evidence for the Zika-microcephaly connection, a formal confirmation doesn’t come as much of a surprise, but the timing of the confirmation has raised some eyebrows. Both Colombia and Venezuela have reported thousands of Zika cases an estimated 40,000 in Colombia, and at least a few thousand in Venezuela and while they have not yet reported an upsurge in microcephaly cases, they could start seeing one soon.

“April and May are the critical months to establish the number of cases we have, and if our situation is similar to what they have in Brazil,” said Fernando Ruiz Gómez, Colombia’s deputy minister of health, in an interview with Public Radio International (PRI).

Venezuela is still waiting for a rise in birth defects as well, according to PRI, and have pediatricians monitoring the number of diagnoses across the country.

There are also plenty of other important questions we desperately need answers to, like whether a fetus is more vulnerable to Zika-related birth defects at a certain stage of pregnancy. One study that analyzed a 2013 outbreak of Zika in French Polynesia indicated that around one in 100 women infected with Zika virus in the first trimester of pregnancy are at risk of their babies developing microcephaly, but researchers are hesitant to generalize this finding to the current outbreak in the Americas. Moreover, Zika is suspected to be linked to hearing loss, vision defects, impaired growth and other abnormalities, with recent evidence suggesting problems can occur in any stage of pregnancy.

Questions also remain over the sexual transmission of the Zika virus. Multiple cases of sexually transmitted Zika have been reported in several countries, including the U.S., and the first case of sexually transmitted Zika was recently reported in Chile, where the Aedes aegypti mosquito  which transmits the disease does not exist. The Centers for Disease Control and Prevention issued detailed guidelines Friday for preventing the sexual transmission of the Zika virus, which were more specific than earlier recommendations in order to keep pace with new information that surfaces almost daily.

“I want to emphasize that this is not an exact science,” Denise Jamieson, a clinical obstetrician on the team leading the CDC’s Zika response, told the Washington Post. “We have so little data to base this on. We’re doing the best we can.”

Throughout all the Zika-related confusion, researchers have also been working to find a vaccine for the virus. But even that could have consequences, as there is mounting evidence that a Zika vaccine could inadvertently provoke more cases of an autoimmune condition known as Guillain–Barré syndrome.

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Lisa Nikolau

Lisa Nikolau is a Madrid-based reporter for Humanosphere, covering gender equality, indigenous rights and poverty in Latin America and worldwide. Find her on Twitter at @lisanikolau, email lisa.nikolau@humanosphere.org or see her latest work at www.lisanikolau.com