Should You Be Worried About Zika?

An unfamiliar virus with new cases popping up every day. A race to understand how it spreads, and who is most vulnerable. For infected patients and the doctors treating them, more questions than answers.

There’s something about all this Zika talk that gives David Abramson déjà vu.

“To me, this looks a lot like the beginnings of HIV/AIDS in the early 1980s,” says the clinical associate professor in NYU’s College of Global Public Health. “These novel viruses don’t come along very often. There is a lot that’s unknown that we’re trying to figure out fairly quickly.”

In several important respects, the viruses themselves aren’t remotely similar, Abramson hastens to add: Compared to HIV, Zika is much less virulent—and, for healthy adults, way, way less deadly. Contracting HIV in the early ’80s, of course, wasn’t just a death sentence; it meant suffering the indignities of an extraordinarily painful and terrifying disease while also, in many cases, becoming the object of fear and scorn. By contrast, 80% of those who contract Zika experience no symptoms at all, though it has been clearly linked to microcephaly and other serious birth defects and pregnancy complications (hence the worldwide emergency).

But from a public health standpoint, Abramson finds some chilling echoes. With emergency funding measures—including a request for $1.9 billion from President Obama and a $1.1 billion Republican plan that would’ve banned funding for Planned Parenthood to provide contraception to curb the sexual transmission of the virus—repeatedly stalled in Congress, the White House announced on August 11 that it would divert $81 million from other programs to pay for the development of a Zika vaccine. (That’s after most of the $589 million shifted in April from fighting Ebola to Zika has run out. The Centers for Disease Control have also adjusted their own budgets in the past months to scrape together additional funding for Zika preparedness.) “In 1981, too, CDC officials were very frustrated by the fact that they couldn’t get the federal government to give them more money,” Abramson warns, “and that turned into a huge problem.”

“Any type of complex emergency becomes another means through which we can understand how populations respond, how systems work and fail, and which kind of policies and interventions can work,” he says. “They all present a chance to learn something and do better next time.”

With Zika, Abramson jumped at the opportunity to observe and learn in real time: Almost as soon as the microcephaly link started making headlines this spring, he and colleagues began an NSF-funded project to monitor U.S. attitudes about the virus. “The thought was that as greater understanding and certainty evolves with Zika, people will become more aware of it, perhaps more concerned about it, and more receptive or willing to pay attention to public health and other emergency messaging,” he explains. So far they’ve done two of four surveys (1,200 people are randomly selected each time), and have also embarked on a separate effort to track changes in attitudes of 200 women of child-bearing age who are living in the Gulf Coast states. The goal of the second study is to take a closer look at how individuals gather information and make decisions about risk. “What are they paying attention to?” Abramson asks. “What media are they listening to? Are they reading newspapers? Seeing things online? Hearing things from friends? From doctors?”

Even for those who are following the news closely, it can be hard to keep up. On August 12, the Obama administration declared a public health emergency in Puerto Rico, where 10,000 residents have been infected. And since the CDC issued a travel advisory for the Wynwood neighborhood of Miami on August 1, the number of confirmed locally transmitted cases there has ticked steadily upward. Then there’s the fact that on July 15, the CDC confirmedthe first documented case of sexual transmission from a woman to a man. From a public health perspective, Abramson says, “it’s never good when we’re saying, ‘Oh, that’s new. We haven’t seen that before.” Case in point: Scientists are still investigating a Utah incident in which a man seemed to have contracted the virus from his father—suggesting that mosquitoes and sex aren’t the only modes of transmission.

With all of that in mind, we asked Abramson to help summarize the facts that we have now, and to explain why so much remains uncertain. Here are some things to remember as the story continues to develop.  

Curbing the spread of Zika from Miami—or anywhere—will require a multi-faceted approach.
Here’s the challenge: “You have a population of people and a population of mosquitoes,” Abramson explains. “Now, the population of mosquitoes live where they live, die within a few weeks, and don’t travel very far.” But the virus itself can travel—because its host can be a mosquito or a person, and people travel. And we know that the virus can be exchanged back and forth between mosquitoes and people. “So the mosquito can not have the virus,” Abramson explains, “go bite someone who does, and then infect the next person it bites. And these particular mosquitoes tend to bite a lot—they’re serial biters.”

That means that when a Zika case pops up somewhere, officials need to test people and mosquitoes in the vicinity to identify everyone who’s infected and keep it from spreading. This is what CDC and Florida Department of Health officials have been doing since Zika landed in Miami.

Because a vaccine is months or even years off, the best defenses now are education and measures to control the population of aedes aegypti mosquitoes that carry the virus. Those include aerial spraying, the use of larvicide tablets, and the removal of standing water (in reservoirs such as garbage cans and discarded tires). The tricky thing about aedes aegypti, though, is that they can breed in very small amounts of water—maybe even just a cupful, Abramson says—and tend to bite indoors, making them tougher to fight on the large scale. People living in areas where aedes aegypti live should close windows, use air-conditioning and insecticides, and consider wearing long sleeves to avoid being bitten. “You can only be so successful with each measure, so you need a multi-pronged strategy,” Abramson says. “But will you reduce the risk to zero? I don’t see how you could.”

In general, Zika symptoms are very mild. That’s the good news and the bad news.
Remember, 80% of people who become infected have no symptoms, and for the 20% that do the symptoms are often pretty minor—perhaps fever and a rash. “But for pregnant women it’s a huge deal—it’s life changing,” Abramson says. “The lifetime cost of caring for a baby with microcephaly is estimated at $10 million. That's enormous—not to mention the emotional cost.”

The combination—an infection that’s a non–event for some and a catastrophe for others—is dangerous. Consider a group for whom Zika presents little risk—say, men with no plans to have children. “They might be spending time outdoors, getting mosquito bites and thinking nothing of it,” Abramson says. “Why should they care?”

The answer, he explains, is that when they’re infected with Zika, they become part of an ever-expanding reservoir where the virus lives. And the bigger the reservoir, the more likely women will become infected and pass the virus along to their babies.

So public health officials—and, perhaps inevitably, concerned mothers-to-be—are charged with convincing people to take precautions against something that doesn’t scare them, on behalf of people they may not even know. “It’s a tough case to make,” Abramson acknowledges, and an important one.

The New York City Department of Health is on high alert.
As a global city with frequent traffic to and from areas—like Puerto Rico and the Dominican Republic—on the front lines of the epidemic, New York has already seen 422 cases of travel-related Zika and is bracing for a locally transmitted case. For months, Abramson says, city officials have been checking mosquito traps around the city, testing for Zika daily, and closely monitoring the communities of people who have tested positive for Zika after travel. If and when the first locally transmitted case hits, they’ll follow Florida’s lead and “draw a circle around the property,” Abramson says, testing people and trapping mosquitoes in the area, and perhaps even spray pesticides within buildings. There are also education efforts underway in neighborhoods whose residents often travel to the Caribbean, and even larvicide tablets being out for people to use in their homes.

NYU’s College of Global Public Health is also working with the Department of Health on modeling how Zika might spread in the city, so that if it happened, officials would know right away where to direct effort and attention. “If you know the neighborhood, the type of mosquito, and the mosquito transmission rates, as well as the density, socioeconomics, and sexual network of the neighborhood, you can estimate what it would look like,” Abramson explains. Of course, no model can predict the future with 100% accuracy, but working through different scenarios now can help the city refine its response when the time comes.

Population risk and individual risk are different calculations.
Take the Rio Olympics, for example: Despite grim headlines out of Brazil (around 1,500 microcephalic babies were born there during a single six-month period), the World Health Organization ultimatelydecided there wasn’t sufficient danger to justify cancelling the Games. “They saw the rate of new infections dropping, the mosquito population declining, and the and rate of microcephalic births declining, and figured they could control the area around the Olympic village to limit the number of bites and infections,” Abramson explains. “They are taking a chance, in that there will be some exported virus from Brazil, and they’re just hoping it’s not so much that it finds a good host community of mosquitoes that will transmit it to others in other parts of the world. So there is a gamble.”

But individuals have to make decisions based on their own appetite for risk, which is why some athletes and their spouses chose not to go to Rio. “If you want zero exposure, don't go to Brazil, for sure,” Abramson says. “If you're pregnant or thinking about being pregnant, don't go to areas where Zika is or has been endemic. That is just good practice.”

It all gets more complicated once you start trying to figure out how to keep the greatest possible number of people safe, with the knowledge that some individuals will get sick no matter what. That’s the challenge posed to public health researchers. “You could say, ‘let’s model how many new cases there might be after the Olympics.’” Abramson explains. “The answer might be ‘not that many.’ But what’s ‘not that many?’ If it’s 1,000 worldwide, that’s not a lot, from a population perspective. But if you were one of those 1,000 cases, it’s everything.”

Abramson’s research on how Americans are making sense of those odds is still underway, but preliminary results suggest that a vast majority—around 80%—know what Zika is, and know that it can cause birth defects. That suggests that campaigns to educate the public are, to some extent, working. But only a much smaller proportion of people surveyed—between a quarter and a third—currently perceive Zika as a direct threat to themselves, their families, or their communities. The question will be whether those figures change—and whether Americans are moved to take precautions—as the number of Zika cases in the U.S. rises. “I don’t think people are overly worried about it yet,” Abramson says.

For whatever reason, Zika doesn’t seem to conjure the same level of dread for most people as did, say, the isolated cases of Ebola in the U.S. in 2014. As deadly as that virus can be, Abramson points out, public health officials have a fuller understanding of how it spreads—so in some ways it is easier to control. “Whatever vision people conjured when they thought about Ebola may have led to too much concern,” he says. As for concern about Zika? “There’s probably not enough yet.”