The U.S. Centers for Disease Control and Prevention (CDC) has warned that sperm donated in three counties in Florida since June 15 may be infected with the Zika virus.

The notice cautions women who are considering trying to become pregnant with sperm coming from 12 sperm banks in Miami-Dade, Palm Beach, and Broward counties.

Zika Transmission Via Sperm

Only Miami-Dade County was previously designated as an area of precaution after the first local Zika transmission in the continental U.S. was confirmed in the Wynwood neighborhood back in July. The community was declared free of the virus last December.

The CDC has now expanded the warning to include Palm Beach and Broward counties, where anyone who has traveled to or between the three counties since June 15 may consider themselves at an increased risk for the virus. This is a change from previous guidance designating June 29 as start of greater Zika risk period.

Donated semen can be stored frozen for certain periods of time.

“It does not necessarily inactivate Zika, so it could be stored in tissue banks, used subsequently and people should be made aware,” explained Dr. Peter W. Marks of the FDA’s Center for Biologics Evaluation and Research at a media briefing.

Dr. Denise Jamieson, incident commander of the CDC’s Zika emergency response, warned that some individuals in the area therefore “may have not realized they are at risk.”

According to CDC, they issued the warning only out of caution, with no reports of Zika transmission via donated sperm already reported. Unlike blood donations that can be screened for the virus, there is currently no screening technique to test Zika presence in semen.

Ongoing probe also found that residents of the three counties frequently travel between the areas and possibly may not realize they could be infected.

The Continuing Threat Of Zika

A person could be infected with Zika without knowing it since about 80 percent of infected individuals exhibit no symptom. Signs that could manifest include rash, fever, red eyes, and joint pain, lasting from a number of days to one week.

Pregnant women are most at risk since they can transfer the virus to their fetus, leading to miscarriage or lasting neurological setbacks. The virus can also result in congenital Zika syndrome, a pattern of conditions in the infant that comprises brain abnormalities, hearing loss, and eye and limb defects.

In a recent study from the University of Texas, the Zika virus was found to alter fetal brain development and cause microcephaly, which can lead to a host of health problems for the child including vision and hearing loss, feeding difficulty, seizures, and developmental delays.

Women from the Florida areas who have been pregnant since June 15 are urged to talk to their doctors about the potential risk. They are also advised to avoid unprotected sex with an infected partner or someone who has lived in or traveled to a location where Zika is present.

The Florida Health Department revealed 280 cases of local transmission in the state as well as 38 more cases where transmission location is yet to be determined.

Today, 70 countries and territories worldwide are dealing with active Zika transmissions, according to the World Health Organization (WHO).