WASHINGTON — For the first time, the Zika virus has prompted public health officials to warn pregnant women to avoid traveling to a part of the continental United States. The travel advisory comes in response to a growing outbreak of the mosquito-borne disease in South Florida.
The state on Monday said there are 10 more people who have been infected with the Zika virus who likely contracted it from local mosquitoes, bringing the total number of such cases in the state to 14. All of the cases have surfaced in a densely populated community north of downtown Miami.
Because the virus can have devastating consequences for a fetus, the CDC urged pregnant women to avoid traveling to the area, and for pregnant women who live and work there to make every effort to avoid mosquito bites and to get tested for possible exposure during each prenatal visit.
It also advised women to use protection during sex, because the virus can be transmitted sexually. Furthermore, the CDC is advising that all pregnant women should be asked about travel to Zika-infested areas during routine prenatal visits.
Any pregnant women who have traveled to Zika areas — including this area of Florida on or after June 15 — are advised to talk with their health care providers and get tested for Zika.
For couples trying to have a baby, women with Zika virus disease should wait at least eight weeks and men with Zika virus disease should wait to attempt conception at least six months after symptoms begin.
CDC director Tom Frieden said the agency issued the travel warning because of the additional Zika infections that were identified in the last 48 hours, and because of new information that indicates mosquito control efforts are not working as well as officials would have liked.
Frieden said it’s possible the insects have developed resistance to some of the insecticides being used, or that the mosquitoes are able to continue laying eggs in ‘‘cryptic breeding places,’’ or that it may simply be that it’s very difficult to do mosquito control in this particular area.
He said more infections are likely, because four out of five people with Zika don’t have symptoms.
Although the CDC issued a similar travel warning for Puerto Rico in January because of widespread transmission on the island, this is the first time the agency has issued such a travel advisory for the continental United States, Frieden said.
The CDC already has two of its experts on the ground in Florida, and six more will be there by Tuesday as part of a rapid-response team. The experts include specialists in birth defects, mosquito control, and community engagement.
In a statement, Scott said state health department officials believe that active transmission is occurring in one several-block area that was announced on Friday. This remains the only area of the state where the health department has confirmed ongoing local transmissions of Zika.
Among the 10 new cases announced Monday, six people are asymptomatic and were identified from the door-to-door community survey that the health department is conducting.
The Zika area is a dense, diverse section about 1-mile-square that includes the neighborhood of Wynwood. It has now become the first area in the continental United States with confirmed local spread of the Zika virus. State and federal officials have warned for months that such a transmission was inevitable.
Wynwood is one of Miami’s trendiest neighborhoods and draws visitors from around the world.
In the 1980s it became a magnet for artists looking for affordable studio space. It’s now internationally renowned for its outdoor art, as bars, cafes, and art galleries spread throughout the neighborhood.
At present, there is no need for the travel advisory to be broader than this specific Zika-affected area, Frieden said. Unlike other mosquito-borne diseases that can be spread by humans and animals, Zika’s transmission can only be spread by mosquitoes that bite infected humans.
The virus spreads most easily in crowded settings where people don’t have access to air conditioning or window screens, and where there are large numbers of Aedes aegypti mosquitoes.
In addition, the mosquito can travel onlyabout 150 yards during its lifetime, so officials have been spraying and using larvicide in targeted areas.
‘‘The frustration is that this wasn’t unexpected,’’ and Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine. ‘‘It’s not like we were caught by surprise. We knew this train has been heading our way.’’
Hotez said the outbreak in Florida is beginning to make clear why lawmakers on Capitol Hill should have appropriated funding for states and counties to prepare for the Zika threat. The Obama administration requested nearly $2 billion to prepare for the virus in February, but the House and Senate left for their summer recess last month without approving any new funding.
Republicans and Democrats in Congress have been deadlocked for months over the fate of a $1.1 billion spending bill that would help fight the spread of Zika.
Democrats in the Senate have blocked the funding package drafted by congressional Republicans over politically motivated language, including provisions that would deny Zika-related funds from being sent to Planned Parenthood and loosen environmental regulations on pesticides. Democrats also want the funding to be increased to nearly $2 billion.
Last week, Senate minority leader Harry Reid, a Nevada Democrat, called on Senate majority leader Mitch McConnell, a Kentucky Republican, to call a special session of Congress.
Senate Republicans responded by blaming Democrats for blocking the House-passed spending bill. McConnell and Florida Senator Marco Rubio, also a Republican, have both said President Obama should use money left over from fighting the Ebola virus to combat Zika.
