Sperm donations from three counties in Florida might contain the Zika virus, according to the Centers for Disease Control and Prevention (CDC).
The organization has recommended that would-be parents “consider this potential risk” if using samples available in Miami-Dade, Palm Beach and Broward counties.
In a press release, the CDC identified the risk of Zika transmission as beginning on June 15, 2016 for the three counties, meaning that sperm samples across the areas’ 12 sperm banks could be compromised. Previously, the CDC had thought only sperm collected from Miami-Dade County might contain the virus.
Scientists believe that Zika can survive in sperm for six months, after an Italian man donated a sample for analysis in August 2016, the BBC reported. Researchers found the virus was still in the man’s sperm, half a year after he first reported symptoms. If Zika infects a fetus, scientists believe it causes microcephaly—where the baby is born with a small head, signifying abnormal brain development.
However, there is currently no evidence to suggest that an infected sperm donation can pass the Zika virus onto a woman, AP reported. CDC officials have acknowledged that any risk of this happening is low, but that caution is still advised.
The organization’s warning follows a recommendation from the Food and Drug Administration (FDA), which regulates sperm donations, that sperm banks shouldn’t accept donations from men with the virus, or who had been in areas where the virus is prevalent. The FDA has told sperm banks to consider refusing samples from men in the three Florida counties. One of the reasons for this, according to the FDA, is that while Zika is easy to test for in blood samples, it’s harder to identify in semen.
The U.S. is now readying itself for the likelihood of more Zika cases in the coming months. The last recorded case of mosquitoes transmitting the virus in Florida was in December 2016, but warmer weather could see the insects begin infecting Floridians again. (The virus can also be spread through sex).
Last year, mosquitoes infected 221 U.S. citizens with the Zika virus. The majority came from Miami, although Texas also reported six cases.