Health officials are reporting the island's first case of cholera since the disease took hold several months ago.
Health Secretary Lorenzo González Feliciano said Monday that the case involved a 70-year-old man who had visited the Dominican Republic for a week.
González said the man is hospitalized in San Juan. Privacy laws prohibited them from releasing more information about the case.
Health officials believe the disease is unlikely to spread because of better sanitation in the U.S. island. It is transmitted by a bacteria and can be all but prevented if people have access to safe water and regularly wash their hands.
It has killed more than 36 in the Dominican Republic, and more than 5,500 people in Haiti since October.
Based on reporting by The Associated Press.