Puerto Rico's health secretary says nearly 500 new cases of Zika have been reported in the US territory in the past week.
Severe birth defects
Ana Rius said that 34,562 cases of the mosquito-borne virus have now been registered, including nearly 2,700 that involve pregnant women. Nearly 290 people have been hospitalised.
Authorities earlier this year declared a Zika epidemic on the island, and health officials have warned that a growing number of babies will be born with severe birth defects known as microcephaly, characterised by abnormally small heads in newborns.
Five people infected with Zika have died in recent months in Puerto Rico, including two who developed complications from a paralysis condition known as Guillain-Barre.
Zika now tied to miscarriage
Human antibody shields mouse foetuses against Zika
New clues on how Zika virus causes microcephaly