New FDA guidelines aimed at cutting the rate of Zika virus transmission in the U.S. reveal just how quickly and easily the virus can spread. According to a report from Reuters, the agency hopes to stem the spread of the virus via donated tissues and cells used during surgery or reproductive procedures.

Scientists fear that the disease could be spread through umbilical cord blood, corneas, bone, skin, stem cells, amniotic membranes, placentas, semen and heart valves, among other sources. The FDA hopes to prevent Zika transmission from human cellular, tissue and blood products. The virus has been reported in 36 countries and territories, with the majority of cases coming from the Western Hemisphere.

According to Peter Marks, the director of the FDA’s Center for Biologics Evaluation and Research, “Though there is more to be learned about the transmission of Zika virus, given what we know about the virus at this point, which also is informed by our understanding of similar viruses, we must address the potential risk of Zika virus transmission by human cells and tissues.”

The FDA recommends that donors should be seen as ineligible if they have previously been diagnosed with the virus, or have spent time in an area with active cases of virus transmission, or people who had engaged in sexual intercourse with a male who has been exposed to the virus. Tissues from deceased people who have had Zika virus within the last six months are also ineligible for donation.

Though the disease is largely spread by mosquitos and thus extremely difficult to avoid or control, ensuring safety for tissue and cell donations is a prudent step towards stopping the spread of the disease. The CDC confirmed in February that the disease can be spread sexually as well, and the World Health Organization has declared the outbreak an international health crisis.

An FDA press release describing the new guidelines can be found here.