The Centers for Disease Control and Prevention (CDC) has released an updated Zika guidance, warning the public that any kind of sexual exposure runs the risk of spreading the virus.

Released on July 25, the new guidance replaces previous recommendations issued by the agency and has been updated to reduce risks for sexual transmission of the Zika virus from both men and women and their partners.

According to the update, sexual exposure to the virus is defined as having had sex without protection with a partner who lives or has traveled to an area where an active Zika transmission is in place. Exposure also encompasses all sexual activities that might expose an individual to genital secretions.

As of July 20, 15 cases of infection due to sexual contact have been reported in the U.S. Based on reports, the longest period of time between symptom onset and sexual transmission was 32 to 41 days in a man.

When tested, the Zika virus RNA was found in semen up to 93 days after symptoms started appearing. Where symptoms don't manifest, test results show that the virus is still present in semen 39 days after a man has departed from an affected area and may have transmitted the virus to a partner.

In women, the virus is detected in vaginal fluids after three days since symptoms began and 11 days in cervical mucus after symptom onset. It is also possible for the virus to be transmitted through menstrual blood.

Aside from wearing protection or abstaining from sex altogether, taking steps to avoid getting bitten by Zika-infected mosquitoes is also recommended by the CDC.

Those concerned about Zika infections after possible sexual exposure are advised to only seek testing once symptoms consistent with the disease are observed. There is limited understanding on how the virus acts in male and female systems so testing might not be conclusive in asymptomatic cases.

Pregnant women, however, are urged to undergo testing whether or not they manifest symptoms if there is a possibility of exposure to the virus, and not just through sexual contact.

Spain just reported its first Zika-related microcephaly birth, marking the first case of birth defect associated with the virus in Europe. The mother was infected while traveling to Latin America when she was 20 weeks into the pregnancy. The baby was born via Caesarean section and is in stable condition, despite having a head "smaller than normal," according to doctors from the Vall d'Hebron University Hospital in Barcelona.

A total of 190 cases have been reported in Spain, the majority of which has been linked with travels to affected areas while one is believed to have been caused by sexual exposure.