Hot Topics: Zika Virus and Allografts, Part 2
There is presently no test available to detect the presence of Zika virus in allograft tissues. This may change if the Procleix Zika Virus Assay now being investigated proves to be an accurate and reliable test. Until then, how are tissue banks managing the risks posed by this viral threat?
It’s important to understand that Zika is not the first virus to affect tissue banking, and the industry has specific protocols already established to protect the tissue supply. This begins with what happens before tissue procurement and acceptance, as the key to keeping Zika (and other viruses) out of the supply chain lies in primary prevention.
Tissue banks long ago implemented stringent donor screening methods and medical records review that form the basis of determining high risk for viruses such as HIV and hepatitis. These same screening methods are effective at assessing risk of Zika, along with other new contagious diseases such as West Nile, Dengue, and Chikungunya. Both deceased and living donors are screened for infectious disease risks routinely, although more public attention is focused on Zika at this time.
In the case of screening living donor mothers for Zika, Allografts.com owner Nikki Couloumbis turned to Craig Thomsen, the Director of Quality Systems for TissueTech, the Miami-based market-leading producer of cryopreserved placental tissues provided by Bio-Tissue and Amniox Medical.
Nikki: “Craig, can you discuss what TissueTech is doing to protect the placental tissue supply from Zika?”
Craig: “Absolutely. First, we do not work with any procurement partners that collect tissues within CDC-identified Zika transmission zones, including Miami-Dade, Broward, Palm Beach in Florida, and Brownsville, Texas. So, tissues potentially most at risk of infection are excluded, including the ones right in our backyard.
Second, we follow procedures that would disqualify outright those donors at risk of Zika. The main step to prevent potential infectious diseases has always been the Donor Risk Assessment Interview.”
Nikki: “In the case of deceased donors this interview is conducted with next-of-kin. But the same type of exhaustive review of risks is conducted with living donors. Can you explain some aspects of what you look for?”
Craig: “The DRAI is a very effective tool. It’s extremely in-depth, with very specific questions mandated by Federal and State authorities, supplemented by specific questions guided by company-specific exclusions. The interview addresses social behavior including drug and alcohol use, sexual partners, and tattoos and piercings. It includes a detailed family history, medical history, and travel history for the mother and her partner to known Zika transmission zones. Any living donor who has lived or traveled to an active Zika virus transmission zone within the last 16 months is not eligible to donate.”
“There are multiple levels of review of every record, including by an independent medical doctor specializing in cytopathology, and the exclusion criteria are very stringent, mandated by both the FDA and TissueTech Standards of Practice.”
Nikki: “I expect that in most cases, women at risk are self-identifying as well, so there is less likely to be a case that gets missed. Furthermore, donors are uncompensated, so there is no incentive to donate if they pose a risk of transmitting Zika. Right?”
Craig: “That’s correct. The public’s high awareness of Zika makes it less likely that a tissue at risk will be donated to begin with. Donors with known infectious disease risks won’t be referred by their obstetricians for tissue donation, and pregnant women living in areas outside of transmission zones who believe they are at risk typically self-identify to their medical providers and request a test. This would be a part of their medical record, and it automatically excludes the mother from birth tissue donation.”
Nikki: “Clearly, it is highly unlikely that Zika-infected tissue will be processed with the extensive procedures that are in place. That’s good news. But let’s discuss your thoughts on sterilization methods. Irradiation has been used by some tissue banks to address concerns about other viruses in allografts.”
Craig: “While that is true, there is no validated method for destroying Zika virus in tissues. The amount of radiation required has not been quantified. So even radiated tissues would pose a risk if primary prevention procedures lapsed. And in the case of placental tissues, biologic value and quality would likely be affected. Truthfully, radiation is not necessary if strict exclusionary procedures are followed absolutely, and that is what we do at TissueTech.”
Nikki: “What is the news on a laboratory test for allografts down the road?”
Craig: “TissueTech has joined with leaders in the industry to jointly petition FDA to amend its recommended guidelines to include testing the donor mother’s blood as a screening tool. The FDA has already approved Zika blood tests for blood donation, so testing placenta donors would seem a logical extension of that. FDA has also approved an investigational study of an assay for Zika virus in tissues which would include placentas. So, yes, we expect progress this year and next year.”
Nikki: “Thanks, Craig, very informative. Our readers will appreciate your insights.”