The Centers for Disease Control and Prevention (CDC) is investigating 14 new cases of sexually transmitted Zika virus in the US.

US health and federal authorities are investigating new reports about the Zika virus being sexually transmitted, including to pregnant women.

"CDC and state public health departments are now investigating 14 new reports of possible sexual transmission of Zika virus, including several involving pregnant women," the CDC said. "In two of the new suspected sexual transmission events, Zika virus infection has been confirmed in women whose only known risk factor was sexual contact with an ill male partner who had recently traveled to an area with local Zika virus transmission; testing for the male partners is still pending."

In the 14 new infection cases, the virus was confirmed in two women who had not traveled to Zika-affected countries but had sexual intercourse with a male partner who had returned from countries where the outbreak is present. Four women tested positive in the preliminary lab test but are waiting for the final results.

The virus has been linked to a pregnancy birth defect called microcephaly, which causes unusually small heads and neurological disorders in babies. It is also suspected of causing a paralyzing condition called Guillan-Barre syndrome.

CDC Deputy Director Anne Schuchat was surprised at the numbers. She said that the possibility of Zika being spread through sexual transmission may be possible. It could lead to complications in terms of preventing the virus from being spread, especially among couples.

"Like previously reported cases of sexual transmission, these cases involve the possible transmission of the virus from men to their sex partners,"

"At this time, there is no evidence that women can transmit Zika virus to their sex partners; however, more research is needed to understand this issue."

Schuchat adds that it is unclear why men who are infected with the Zika virus are the only ones who can transmit the virus to their partners. Researchers determined that it can stay in the man's semen but it is not known how long it will stay there. However, this could be a good thing as the virus is not yet spread through mosquitoes, so it makes it easier to identify sexually transmitted cases in the country.

Earlier this month, the sexual transmission of the virus to the sexual partner of a Texan individual who traveled from a Zika-infected country was confirmed. A press release advised the public to use condoms or practice abstinence to protect against the virus and other sexually transmitted diseases.