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SAN JUAN — On this lush Caribbean island where window screens are scarce and mosquitoes rule, public health officials are preparing for a major battle against the Zika virus. But they are also gearing up to wage war on another foe: complacency.

Based on the way related mosquito-spread viruses have swept through Puerto Rico in the past, health authorities predict Zika will hit this island hard, with as many as one in five residents expected to be infected at some point this year.

But Puerto Ricans aren’t concerned about being bitten by mosquitoes. They view bouts of diseases like dengue fever and chikungunya — painful and unpleasant though they may be — as no more avoidable than the occasional flu. That, officials said, means helping to protect them from Zika, and persuading them of the importance of the effort, isn’t going to be easy.


“It’s part of our daily life,” explained Carmen Perez, a behavioral scientist at the Centers for Disease Control and Prevention’s dengue branch, headquartered in San Juan. “Getting dengue is like ‘Oh, dengue again.’”

Because trying to prevent Puerto Ricans from getting infected would be as futile as trying to keep sand out of sandals at the beach, public health efforts are focusing on protecting a population facing a particular danger: pregnant women.


Zika infection during pregnancy is believed to interfere with fetal brain development in some instances; in those cases, babies can be born with microcephaly — smaller than normal heads — and malformed brains.

Although scientists have been cautious about confirming a causal relationship between infection and birth defects, the director of the CDC’s division of vector-borne diseases, Dr. Lyle Petersen, told reporters this week: “I don’t think there’s any question about that any longer.”

In Puerto Rico, there are already five pregnant women among the 117 people who have tested positive for Zika. The CDC is working on the assumption that nearly 700,000 residents of the island may become infected with the virus before the year is out — vastly more than in the continental United States, where the mosquitoes that transmit Zika are primarily concentrated in the south.

The agency’s director, Dr. Tom Frieden, will travel to Puerto Rico next week to assess the CDC’s efforts to help respond to Zika.

“There’s going to be infected women. And there might be babies born with developmental problems. So we’re not saying we’re going to eliminate all risk,” Brenda Rivera, Puerto Rico’s territorial epidemiologist, told STAT. “But we have to decrease it as much as possible. We have to do everything in our power to keep those populations safe.”

Style over safety

Julimar Rivera, four months pregnant, is among the people public health officials would most like to protect. She’s only 19 and she’s already contracted dengue and chikungunya in her lifetime.

“I’m worried that I’ll get bitten and something will happen to my kid,” she said on a recent day as she waited for a government-run Zika information session to begin. “I’m always carrying two bottles of Off.”

Rivera might be more attuned to the threat of Zika than most ordinary Puerto Ricans. But she wasn’t wearing light-colored clothes, or long sleeves, or long pants — the standard uniform suggested for avoiding mosquito bites. Her short-sleeved dark olive green dress and bare legs were typical in San Juan, where looking chic can take priority over covering up.

Alexandra Santiago, 22, said she knows she ought to wear tops with long sleeves, but until recently she didn’t own any. Pregnant with her second child, she bought some. But that doesn’t mean she always wears them.

“Sometimes I do, sometimes I don’t,” Santiago said, noting the heat by way of explanation. “It’s Puerto Rico.”

Puerto Rico - WIC Center
Alexandra Santiago, 22, with her 3-year-old son Sebastian Martinez, speaks with Alejandra Seda, nutritionist and registered dietitian, at the WIC Clinic in San Juan. Santiago is four months pregnant. Erika P. Rodriguez for STAT

Modest weapons to fight the virus

Health officials here have modest weapons at their disposal.

Public awareness campaigns are being planned. So too is targeted mosquito control spraying around the houses of women who are pregnant — if that proves to be acceptable to the homeowners.

Pregnant women will be given Zika kits — tote bags containing mosquito repellant, a few condoms as a reminder of the risk of sexual transmission of the virus, a bed net, some larvacide pellets to put into septic tanks or standing water, and some pamphlets.

Another option under consideration is providing screens for the windows and doors of the homes of pregnant women who agree to let a health department team visit to look for and eliminate mosquito breeding sites, said Dana Miró, executive director of a prenatal health program for women called Woman, Infant, Children.

WIC, as everyone calls it, is the vehicle through which many Zika response efforts are being delivered. The agency already provides nutritional counseling, food vouchers, and other assistance to 93 percent of pregnant women in Puerto Rico, so it knows how to reach this population.

There are roughly 15,000 pregnant women right now on the island, according to Miró, who added that in an average year, about 29,000 Puerto Rican women are pregnant.

WIC has been calling women on its registry and asking them to attend a Zika information session. As of late last week, nearly 5,000 had — but only about one-quarter agreed to let health department staff check their homes for ways to reduce mosquito populations.

It remains to be seen if an offer of free screens would improve that rate. Among many Puerto Ricans, there is a belief that screens make homes hotter by impeding air flow, said Dr. Jose Rigau, a retired physician and epidemiologist who lives in San Juan.

And the reality is that people don’t have to have swarms of mosquitoes in their homes to catch Zika or its viral cousins. Rigau said a 1990s study showed the risk of dengue infection on the island rose in houses that had as few as two female mosquitoes — the ones that bite — per person. “It’s just two, per person, spread throughout the house. So it’s not like you’re seeing mosquitoes constantly,” Rigau noted.

A mosquito that loves the indoors

Still, Aedes aegypti mosquitoes — the species that is known to transmit Zika — love to live inside. In Puerto Rico, they are always around.

“We live side by side with them everyday,’’ said Tyler Sharp, the acting head epidemiologist at the CDC’s dengue branch. “Everybody that I know, myself included, has mosquitoes in their home, in their apartment. You do what you can to avoid them. But they are omnipresent.”

The challenges in Puerto Rico are significant, acknowledged Stephen Waterman, director of the branch. “There’s been a lot of complacency about dengue here. Obviously, Zika raises a whole other level of fears, but I think there’s a lot of community outreach that needs to be done.”

“The chikungunya outbreak in 2014-15 infected thousands of people. And we expect to see the same thing happen with Zika,” he said flatly. “We’re not going to be able to prevent every infection, or every infection in pregnant women. But I think we can probably reduce some of them. And every one of them is worth preventing.”

Puerto Rico - WIC Center
Educational material about the Zika virus at a temporary WIC information location in San Juan. Erika P. Rodriguez for STAT

A significant challenge

It will take more than informing pregnant women to lower their risk of Zika infection. Neighbors and communities will need to work hard at getting rid of the standing water in which Aedes mosquitoes lay their eggs.

Brenda Rivera, Puerto Rico’s territorial epidemiologist, thinks that because the virus threatens babies, people will be galvanized to act. Waterman agrees, noting Puerto Rican culture is very family-oriented.

“If we can sort of tap into that sensitivity and concern about making sure that families are safe, that pregnant women are safe, then that may contribute to community participation,” he said.

The local media have been featuring stories about Zika prominently. But to date the public awareness campaign — to inform people here of what they can do to reduce the population of Aedes mosquitoes — has not started.

Brenda Rivera said the department of health wants to see what that work yields before it commits to public service announcements.

“Some of the critical steps, before we put a lot of money into this effort, it’s understanding what in the messages needs to be included,” she said.

That’s not an academic exercise. Rigau recalled a public service campaign in the 1980s warning about the risks of dengue hemorrhagic fever — a rare but life-threatening manifestation of dengue infection.

In the commercial, a popular male soap opera star told parents returning for the funeral of their child that her death was caused by mosquitoes that bred on their property.

A study done a decade later showed that people remembered the campaign more than any other — but they hated it. Rigau said they also reported changing the channel whenever it aired.