The government urged health officials around the country Friday to get ready now in case there are outbreaks of the mosquito-borne Zika virus in the U.S. this summer.

A Zika epidemic has been sweeping through Latin America and the Caribbean, and officials think it's likely some small clusters of Zika will occur in the U.S. when mosquito numbers boom.

At a "Zika Summit" on Friday, experts prodded some 300 state and local officials gathered at the Centers for Disease Control and Prevention headquarters to make Zika response plans now.

When West Nile virus — transmitted by a different mosquito — moved through the U.S. about 15 years ago, health officials were caught flat-footed, noted Dr. Georges Benjamin, executive director of the American Public Health Association.

"This is an opportunity to get ahead of the curve," he told the summit's attendees.

The Zika virus causes only a mild and brief illness, at worst, in most people. But in the last year, infections in pregnant women have been strongly linked to fetal deaths and to potentially devastating birth defects, mostly in Brazil.

The virus is spread mainly by Aedes aegypti mosquitoes, which also live in parts of the U.S. It was thought to be mainly in the South but the CDC revised its map this week, showing the mosquito has been found in parts of the Midwest and Northeast.

Officials don't expect Zika to be a big problem, though, in the U.S. for a number of reasons, including the widespread use of air conditioning and screens. The Zika mosquito likes to bite indoors. They think the clusters may be small and surface only in a few states — most likely Florida and Texas. But they don't know for sure.

So far, there have been no Zika infections in the U.S. caught from mosquitoes. More than 300 illnesses have been reported, all linked to travel to Zika outbreak regions.

About 350 additional cases have been reported in U.S. territories, most of them in Puerto Rico, where mosquitoes are already spreading the virus. Together, dozens or even hundreds of births in the 50 states and territories could be affected in devastating ways by Zika, said Dr. Edward McCabe of the March of Dimes, who spoke at the summit.

"We have a few short weeks to stop the Zika virus from gaining a foothold," McCabe said.

During the summit, state and local officials were encouraged to map where the Zika mosquito lives and breeds in the state and which insecticides would work best in their area.

The Zika response will likely mean workers will go door to door, sometimes asking to go on properties and even spray. That's different from the truck- and aerial-spraying seen in conventional mosquito eradication efforts.

It will be a kind of campaign not seen in this country since efforts to wipe out yellow fever in the 1950s and 1960s, and it will take different kinds of equipment, approaches and more staff, CDC officials said.

Local health officials at the summit said the work ahead is daunting, especially since it's not clear where they're going to get the money. And health departments are already struggling financially, said Dr. Jeff Duchin, a Seattle-based county public health official who was at the meeting representing the Infectious Diseases Society of America.

"Our priority is to make sure we have enough resources to meet the threat," Duchin said.

Paul Ettestad, New Mexico's public health veterinarian, said some of the state's counties only have a handful of people doing mosquito control work — the same people who also handle snow removal in the winter

"They don't have much," Ettestad said

The Obama administration in February requested nearly $2 billion in emergency funding for Zika response work. Congressional leaders have not formally voted on the request.

One of the things money is needed for, officials said, is better and faster blood tests for Zika. Now, it takes between a few days to a week to get results.

If Zika starts spreading in the U.S, women of childbearing age are going to be "intensely concerned," predicted Dr. Bill Foege, a former CDC director and expert on global health. "They're going to want to know if they are infected and they're not going to want to wait a week."