Zika infections are increasing rapidly in Puerto Rico, U.S. health officials said Friday.

“This could lead to dozens or hundreds of infants being born with microcephaly in the coming year,” said Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention (CDC),” in a press conference CNBC reports.

The CDC is tracking Zika infections in the donated blood supply in Puerto Rico, CNBC reports. The percentage of blood that tests positive for Zika has been on the rise, with the most recent data showing that for the week of June 5-June 11, 1.1% of blood donations in Puerto Rico tested positive for the virus.

According to officials, even this apparently small amount of Zika implies a higher rate of infection among the people of Puerto Rico. Frieden said there may be a 2% rate of infection in Puerto Rico each month.

He added that over the course of many months there is a “substantial chance a woman would become infected.” Blood centers in the continental U.S. are using questionnaires to determine if people have traveled to places where Zika is actively spreading. In Puerto Rico, donated blood that tests positive for the virus is removed from the supply.

Zika can cause microcephaly in the babies of infected pregnant women, which leads to underdeveloped brains and smaller heads. The CDC said there have been six cases of pregnancies with Zika virus-linked birth defects in the U.S.

[CNBC]

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