Hologic Inc won emergency U.S. authorization to sell its Zika test, expanding the number of public and private labs that can test for the virus as health officials brace for a rise this summer in the number of infections.

The U.S. Food and Drug Administration granted emergency use authorization for the company's Aptima test to detect Zika virus in human serum and plasma specimens. The test will be available for use immediately in every U.S. state as well as Puerto Rico and U.S. territories, the company said.

Aptima is the third commercial test to be granted emergency use authorization by the FDA. Focus Diagnostics and Germany's altona Diagnostics GmbH were also given emergency use authorization. The Centers for Disease Control and Prevention also can test for the virus.

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In February, the World Health Organization (WHO) declared Zika a global public health emergency.

The virus has been associated with microcephaly, a birth defect characterized by an unusually small head and potential developmental problems. On Thursday, U.S. health officials reported three babies born with birth defects likely linked to Zika infection in the mother during pregnancy.

Authorities in Brazil, the country hardest hit by the virus, have confirmed more than 1,400 cases of microcephaly in babies whose mothers were exposed to Zika during pregnancy.

On Tuesday, the WHO said there was a "very low risk" of further spread of the virus for people attending the Olympic Games, to be held in Brazil in August.

Shares of the company were up about 1.5 percent at $34.30 in extended trading on Friday.