June 5 (Reuters) - Puerto Rico on Monday declared that the 2016 Zika epidemic is over, saying transmission of the virus that can cause birth defects when pregnant women are exposed has fallen significantly.

About 10 cases of the mosquito-borne disease have been reported in each four-week period since April 2017, down from more than 8,000 cases reported in a four-week period at the peak of the epidemic in August 2016, the Puerto Rico Health Department said in a statement.

The U.S. Centers for Disease Control and Prevention, however, has not changed its travel advice, noting that pregnant women should not travel to Puerto Rico.

“At this time, there are no plans to change CDC’s travel recommendations for Puerto Rico. The agency is reviewing recent surveillance data and will update recommendations based on review of data,” CDC spokesman Tom Skinner said in an emailed statement.

On its website, the CDC cites public health reports saying that “mosquitoes in Puerto Rico are infected with Zika virus and are spreading it to people.”

CDC acting Director Dr. Anne Schuchat said in a statement that she is “pleased that the peak of the Zika outbreak in Puerto Rico has come to a close.” However, she said, “We cannot let our guard down.”

Schuchat said CDC will continue to focus on protecting pregnant women and work closely with the Puerto Rican health department to support Zika surveillance and prevention efforts on the island, which is a U.S. territory.