The first case of Zika virus in Cuba was detected in a Venezuelan doctor who came to the island for postgraduate studies, the health ministry said.
The 28-year-old woman, who arrived in Cuba on February 21, is hospitalized at the Pedro Kouri Tropical Medicine Institute in the capital Havana.
The doctor said her husband contracted Zika two months ago and that her brother-in-law also got sick two weeks before her trip to Cuba, the health ministry said in a statement carried by state newspaper Granma.
None of the other doctors have shown any symptoms so far, according to the ministry.
Cuban authorities have stepped up health checks at airports and ports on travelers from the Americas and Angola, where a yellow fever outbreak has been detected.
Foreign students are required to present health certificates on arrival in the country, and those from countries that have reported cases of Zika, dengue, chikungunya, and yellow fever must also make written statements about their health.
Those with fever will be taken to medical facilities for treatment.
The rapidly expanding Zika virus -- which has affected more than 20 Latin American countries -- is suspected to be the cause of a sudden increase in cases of neonatal microcephaly, a severe deformation of the brain and skull among newborns.
Last week, Cuban President Raul Castro ordered the mobilization of some 9,000 soldiers to fight the Aedes aegypti mosquito that transmits the virus.
Countries throughout the region have launched operations to eliminate pools of stagnant water where the mosquitoes, which also spread dengue and chikungunya viruses, can breed.