/ Updated 
By Associated Press

As many as 50 pregnant women a day are becoming infected with Zika in Puerto Rico. The best defense is aerial spraying, said Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention, (CDC) to The Associated Press.

Zika is a virus spread by mosquitos that can cause microcephaly, which results in babies being born with brain damage and abnormally small heads.

Frieden said Puerto Rico, which is a U.S. territory, lacks an integrated mosquito control program.

"If any part of the continental U.S. had the kind of spread of Zika that Puerto Rico has now, they would have sprayed months ago," said Frieden. "This is more a question of neglect than anything else. ... If we wait until children with microcephaly are born, it will be too late. That's the problem."

The island is debating whether to spray with the insecticide Naled, which has sparked protests over concerns about the impact on human health and wildlife. Puerto Rico has one of the highest asthma rates in the world.

Frieden said less than two tablespoons of Naled would be used per acre. He said the product was used last year on 6 million acres in Florida, including Miami. He also said it was used in New York and there was no increase in the number of asthma cases there.

Gina McCarthy, administrator for the U.S. Environmental Protection Agency, told the AP that the spraying "can be done safely and effectively and is perhaps the most important tool we can use right now to change the trajectory."

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Legislators are holding public hearings over the fumigation proposal, though it will be up to Gov. Alejandro García Padilla to implement the spraying, which would be paid for by the U.S. federal government.

A total of 339 pregnant women in Puerto Rico have been diagnosed with Zika. Puerto Rico reported its first microcephaly case in May; it involved a fetus who tested positive for Zika.

Overall, Puerto Rico has reported nearly 2,400 Zika cases, 44 hospitalizations and one death. In addition, 16 people have been diagnosed with a temporary paralysis condition known as Guillain-Barre that has been linked to Zika infections.

More than 20 percent of Puerto Rico's 3.5 million people could be infected with Zika in an outbreak expected to peak by this summer, according to the CDC, though local health officials have said that number is too high.

But Frieden said part of the issue is that 8 in 10 people show no symptoms or have mild symptoms.

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