Zika on Our Doorstep

By Brenda Goodman, MA
WebMD Health News

Reviewed by Arefa Cassoobhoy, MD, MPH

March 7, 2016 -- San Juan, Puerto Rico -- A new souvenir that no one wants may soon be making its way home with Americans from their beach vacations here: the Zika virus.

The mosquito-borne virus is expected to plow through Puerto Rico with little to slow its spread.

This island U.S. territory is $70 billion in debt, an amount its governor last year called "not payable." Funding cuts have crippled public programs, leaving local health authorities shorthanded and without enough supplies.

Health authorities fear as many as 700,000 people could have Zika in Puerto Rico by the end of the year. With 36,000 pregnant women living here now, experts fear the virus will take a heavy emotional and financial toll.

Being infected with Zika during pregnancy appears to dramatically raise the risk of health problems in babies. The most devastating of these may be microcephaly, which causes infants to be born with abnormally small heads and malformed brains.

Because Puerto Rico is a major tourist destination that is closely connected to the U.S. mainland, infectious disease experts are closely watching the climbing numbers of Zika infections here:

  • Roughly 100 daily flights drop Americans at these balmy blue waters and spring break-ready beach bars.
  • Nearly 40 cruise ships pass through the Port of San Juan each week, dropping off roughly a million tourists to shop and eat as they island hop through the Caribbean.
  • About 90% of the people who fill the hotels here each year are Americans, according to the government-run Puerto Rico Tourism Company.

Puerto Ricans, too, often travel back and forth to the U.S. "There's a big traffic back and forth between Miami and New York and perhaps other cities, too," says Robert Tesh, MD, an expert in emerging infectious diseases at the University of Texas Medical Branch in Galveston.

"If they have a health problem in San Juan, it's going to affect the U.S. as well," he says.

President Obama has asked Congress to approve $1.9 billion in emergency funding to fight Zika at home and abroad. That includes $250 million for Puerto Rico's Medicaid program.

CDC director Tom Frieden, MD, is touring Puerto Rico this week to further highlight the island's plight.

"I think the probability of a catastrophic Zika epidemic in Puerto Rico is real," says Jonathan Day, PhD, a professor at the University of Florida's Medical Entomology Laboratory in Vero Beach.

"It will be places that are in the midst of an ongoing epidemic that will be the most dangerous. The probability of that traveler becoming infected and bringing virus back with them is real."

Travel is how the virus likely zipped around the globe so quickly in the first place. Since the first alerts about the current outbreak in Brazil in May of last year, 46 countries have reported "local transmission" of the virus. Local transmission means the virus is being carried by mosquitos in the area.

That hasn't happened in the U.S. yet, but experts say it's only a matter of time, since 40 million Americans -- including 500,000 pregnant women -- travel to countries that are reporting active Zika outbreaks right now.

Day is quick to point out that the U.S. probably won't see a similarly high infection rate.

Here's why: If a tourist from Minnesota, for example, picks up Zika on a trip to Puerto Rico and flies back to the U.S., he's landing in a place where it's unlikely he'll come into contact with the mosquitoes that spread the virus. If he's not bitten, and doesn't infect a sexual partner, the infection won't spread widely.

But Day thinks some pockets, like Key West, FL, and other areas along the Gulf Coast that have warm temperatures, will probably see clusters of locally transmitted Zika.

Puerto Rico's balmy weather -- and its large number of people per square mile -- make conditions ripe for a Zika outbreak. With about 3.6 million residents sharing 3,500 square miles, the island rivals India for population density.

In this tropical climate, many dwellings lack window screens and air conditioning -- luxuries that protect homes against mosquitos. Without them, the species of mosquito that spreads Zika and the closely related viruses chikungunya and dengue moves right into the house to live alongside its residents. The mosquitoes lay eggs in sink drains and plant containers, and spend their days lurking in the damp darkness of closets or hiding under couches, waiting for someone to come home, sit down, and turn on the TV.

And virtually no one here has ever been exposed to Zika before, which means the body's own defense system has little in its arsenal to blunt the attack.

That makes it all too easy for the virus to spin through its infectious cycle as it passes from mosquito to person to the next mosquito and the next person.

In most cases, Zika infection is mild and temporary. Only 1 in 5 people are even thought to experience symptoms -- headache, fever, joint pain, and red eyes -- that clear up in about a week.

Zika has also been linked to a serious complication of viral infections called Guillain-Barre syndrome, which causes temporary paralysis and can be deadly if the lungs are involved and medical care is not given quickly.

So far, 14 pregnant women have been diagnosed with Zika, out of about 150 total infections on the island. While it's too soon to know about pregnancy complications, the biggest fear is that more pregnancies will result in babies with microcephaly. In severe cases, children with microcephaly may die soon after birth, or they may need a lifetime of care and support services.

With the rainy season -- and a mosquito boom -- coming to Puerto Rico in April, the CDC has deployed 35 additional personnel to support the 50 staff members who already work in the agency's dengue branch here.

They're here to support the efforts of the local health department, says Steve Waterman, MD, chief of the CDC's dengue branch. CDC staff will help train workers to run lab tests, help with new pregnancy education campaigns, and support local doctors as they learn how to identify and manage possible Zika-caused birth defects.

"There's a history of complacency about dengue in Puerto Rico. There's a lot of work to do" to try to encourage people -- residents and tourists -- to take the virus seriously, he says.

"I think this is a massive effort. It would overwhelm a state health department in the U.S. if they had the same problem," he says.


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SOURCES: Robert Tesh, MD, professor, Professor, Departments of Pathology, Microbiology and Immunology, Preventive Medicine and Community Health, at the University of Texas Medical Branch in Galveston. Steve Waterman, MD, Chief, CDC's dengue branch, San Juan, Puerto Rico. Jonathan Day, PhD, professor at the University of Florida's Medical Entomology Laboratory, Vero Beach, FL. CDC: CDC director's testimony to the House Energy and Commerce Committee, March 2, 2016.

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