U.S. Democratic presidential candidate Hillary Clinton is dispatching two top aides to Puerto Rico this weekend for a fact-finding trip to learn more about the Zika virus, her campaign said on Tuesday.

Clinton aides Amanda Renteria and Ann O'Leary will meet with officials on the island territory, which has become a breeding ground for the virus in the United States.

In Puerto Rico, there are some 400 confirmed cases of Zika, which is spread by mosquitoes and through sexual contact, and public health experts predict that eventually as many as 80 percent of the island's 3.5 million residents could become infected.

Clinton said in a statement provided by her campaign to Reuters that more must be done to combat the spread of Zika in Puerto Rico, which has an abundant mosquito population and also a decades-long recession that has made curbing that population difficult.

"The Centers for Disease Control and Prevention is taking this threat seriously and it has been working closely with Puerto Rico. But I want to be sure that we are truly doing all we can to fight the Zika virus from spreading," Clinton said.

"Zika is an urgent problem and we need to act now," Clinton added.

U.S. health officials have concluded that Zika infections in pregnant women can cause microcephaly, a birth defect marked by small head size that can lead to severe developmental problems in babies. The World Health Organization has said there is strong scientific consensus that Zika can also cause Guillain-Barre, a rare neurological syndrome that causes temporary paralysis in adults.

The connection between Zika and microcephaly first came to light last fall in Brazil, which now has confirmed more than 1,100 cases of microcephaly that it considers to be related to Zika infections in mothers.

CDC director Tom Frieden visited Puerto Rico last month to assess the situation on the island, which is known to have the Aedes aegypti mosquito, the species linked to repeated outbreaks of dengue and now Zika. It is present in about 30 U.S. states.

Clinton is facing off against U.S. Senator Bernie Sanders in a Democratic nominating contest in New York on Tuesday. New York is home to the largest Puerto Rican population in the 50 U.S. states.

(Reporting by Amanda Becker Editing by W Simon)