Alan Gomez

USA TODAY

MIAMI — The director of the Centers for Disease Control and Prevention delivered a grim assessment Tuesday of the government's ability to contain Zika, saying it's too late to stop the dangerous virus from spreading throughout the United States.

"Zika and other diseases spread by (the Aedes aegypti mosquito) are really not controllable with current technologies," CDC Director Thomas Frieden said. "We will see this become endemic in the hemisphere."

Speaking at the CityLab 2016 conference in this southern city, Frieden encouraged mayors and city officials in attendance to bolster mosquito control divisions, public health budgets and outreach to citizens to educate them about the looming threat.

Frieden said the federal government is hamstrung when responding to public health emergencies like Zika, which can cause devastating birth defects in babies born to women infected while pregnant.

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Frieden said his agency has been forced to cut back on several programs in order to respond to Zika, including HIV testing and immunization programs. The agency also had to pull back money from an ongoing program to prevent another Ebola outbreak in West Africa, he added.

"We had to take money from every state in the country and give it to the states that needed it more for Zika," Frieden said. "We do the best we can with the cards we’re dealt. But this shows how really important it is that there is emergency funding."

The CDC receives a $14 billion annual budget, but Congress only allows the agency to use $2.5 million to respond to emergencies, leading to the drastic cuts in several programs, Frieden said. By comparison, Frieden had nearly $40 million in emergency funds as commissioner of the New York City Health Department, he said. The Federal Emergency Management Agency, meanwhile, has broad discretion over its $13 billion annual budget.

The CDC, however, doesn't have such flexibility. The agency must seek congressional approval anytime it responds to a public health emergency. The result: When Zika started reaching the U.S. earlier this year, the CDC requested an emergency spending bill from Congress, but partisan bickering led to a months-long delay before a $1.1 billion bill passed last month.

"When there’s an earthquake or a tornado, FEMA doesn’t go to Congress and say, ‘Would you give us money for this?’" Frieden said. "They have a fund."

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Frieden also said the best-case scenario for finding a vaccine for Zika is "two to three years" away.

The CDC director did have some encouraging news based on lessons learned in Miami-Dade County, the first and, so far, only U.S. county to experience local transmission of the virus.

More than 4,000 people who acquired Zika while traveling abroad have been identified in 49 of 50 U.S. states — only Alaska has been spared. But Miami-Dade County remains the only place where people have contracted the virus from local mosquitoes.

Frieden said the first area hit, the popular Wynwood neighborhood of Miami, was able to remove itself from the active transmission list in part by conducting aerial mosquito spraying. The decision was controversial among local residents, who feared the health consequences of chemicals found in mosquito sprays.

But Frieden said the move wiped out the neighborhood's mosquito population nearly overnight. "Literally within a day, the mosquito counts went to zero," he said.