The news was first reported on Monday by Military Times.

As of July 26, the C.D.C. was reporting active Zika virus transmissions in most of Central and South America with the exception of Chile and Uruguay, as well as in Papua New Guinea, Samoa, Tonga, the Marshall Islands, American Samoa and Fiji. The C.D.C. was also reporting active Zika transmissions in Cape Verde, off the coast of Senegal.

The Army is working with outside scientists to develop a Zika vaccine, military officials said.

Last month a Congressional measure to help fund the Zika response died amid bickering between Democrats and Republicans and despite agreement that the virus, which can cause serious birth defects, is a public health emergency. It failed after House Republicans refused to accept a bipartisan compromise reached in the Senate, and inserted clauses that reignited old disputes over government financing for Planned Parenthood.

Last week Florida officials reported the first signs of local transmission of Zika in the continental United States, in a Miami neighborhood. By Monday, federal health officials were urging pregnant women to stay away from the neighborhood, in apparently the first time that the C.D.C. has advised people not to travel to a place in the continental United States.

Officials said that the number of Zika cases in Florida caused by local mosquitoes had risen to 14 from four announced last Friday: 12 men and two women. But they maintained that they did not expect the number of cases there to grow into anything like the epidemic that has raged across Latin America in recent months.

The Pentagon did not give details about the status of the pregnant woman or her baby.

Zika has strained health resources throughout Latin America. The epidemic is now affecting Puerto Rico, with two percent of recent blood donors there reportedly infected, and hundreds of pregnant women testing positive.