BOGOTÁ, Colombia — Health officials here on Monday declared an end to the Zika epidemic in Colombia, the first time a South American country had turned the tide on the disease, they said.

The Zika virus, which causes an illness related to dengue and is spread by mosquitoes, has infected roughly 100,000 Colombians and is linked to more than 20 cases of microcephaly, a birth defect that causes babies to be born with abnormally small heads.

While health officials said the number of new infections had decreased to 600 new cases a week, they added that they still expected a limited number of new cases in the coming months as the disease wound down.

“The period the disease will remain local still hasn’t been determined,” Fernando Ruiz Gómez, the deputy health minister, said at a news conference. “There may eventually be extended outbreaks.”

The problem of microcephaly will also continue to haunt the country, the officials said.

Nearly 18,000 of those infected were women whose pregnancies have been under watch by health officials for birth defects, the officials said. Mr. Ruiz Gómez said he expected a spike in cases of microcephaly in September and October, as women who are infected begin to give birth.

Birth defects have been a source of debate for Colombia, which has limited abortion laws, creating a quandary for some women who were infected.

In addition to microcephaly, Zika has been linked to a spike in Guillain-Barré syndrome, an autoimmune condition that causes temporary paralysis and in some cases has proved fatal.

Officials say the Zika epidemic in Colombia began in September in the town of Turbaco, a short distance from Cartagena. Since then, it has spread widely throughout Colombia, where the government mounted a public health campaign and a wave of fumigations.

In late March, the World Health Organization said the virus had peaked in Colombia, prompting the country to scale down its projections of the disease’s spread.

The W.H.O. has declared an international health emergency over the spread of the virus, which is expected to infect millions of people. It has reached the United States, with reports of about a dozen children born with Zika-related microcephaly since the spring, as well as Europe. On Monday, a woman infected with the virus gave birth to a child with microcephaly in Barcelona, Spain.

Brazil has been hit hardest. The country has borne the brunt of the infections ahead of the arrival of tourists and athletes from around the world for the 2016 Olympic Games in Rio de Janeiro next month.