WEDNESDAY, May 9, 2018 (HealthDay News) – Since 2016, each US blood donation has been individually tested for the Zika virus. A new study suggests it's not worth it.
Researchers of the American Red Cross found that out of about 4 million donor blood samples tested over 15 months, only eight were positive for mosquito-borne Zika viruses. Even fewer were potentially infectious.
And all came at a cost of nearly $ 42 million, the researchers reported.
Experts said it was a waste of money and precious laboratory resources – and that could control Zika's blood supply
"We do not argue that we should not seek it," said Senior Researcher Susan Stramer, Vice President of Scientific Affairs at the Red Cross.
The problem, she said, is in the way it's done.
Under the guidance of the US Food and Drug Administration of 201
And based on the new findings, it looks like it's "over the top".
The Zika virus is a mosquito-borne infection. If contracted during pregnancy, it can cause serious birth defects such as microcephaly – an abnormally small head and brain.
In 2016, 5,168 cases of Zika-related illnesses were reported in the United States. According to the United States Centers for Disease Control and Prevention, the virus generally causes fever, rash, headache and joint or muscle pain.
This year, according to the CDC, US states have reported 21 cases – all in people who had traveled to parts of the world severely affected by Zika, such as the Caribbean, Central and South America
often causing the infection but no symptoms, which means that people who carry the Zika virus can unknowingly donate blood  In August 2016, the FDA said that all US blood donations should be individually screened for Zika gene material using a newly developed test.
Previously, the Red Cross had only investigated donor blood in states with suspected Zika transmission risk. This was achieved through so-called "mini-pool" tests: Instead of testing each donation individually, Stramer explained, the blood was tested in batches of 16 donors each. This makes the process more efficient, she noted.
Minipool tests are nothing new, Stramer said. As used in the study of donor blood for HIV and the West Nile virus.
After the FDA guidelines were released, the Red Cross switched to individual blood samples for Zika.
Stramer's team found this over 15 months and tested nearly 4 million individual samples, screening nine samples that were positive for Zika. One of them came from a person who had received an experimental Zika vaccine – which means that eight people had mosquito-borne infections.
Of these donations, only four appeared potentially infectious,
The total cost of the screening approached $ 42 million, the study found. In other words, it cost nearly $ 5.3 million to receive a Zika-positive donation.
The results are published May 10 New England Journal of Medicine .
It's not clear what the risk of infection is from donor blood, Stramer said. But there were four cases, all in Brazil, where people were apparently infected by blood transfusion with Zika. However, none of them became ill.
"To my knowledge, there were no [disease] cases of blood transfusions," Dr. Evan Bloch of the School of Medicine at Johns Hopkins University in Baltimore
Bloch, who wrote an editorial published in the study, agreed with Stramer in the bottom line. Donor blood screening for Zika is reasonable, but the current process is flawed.
"It could be modified to a more rational approach," said Bloch.
Both he and Stramer specifically pointed to the minipool approach  Money is not the only problem, according to Stramer. Individual tests require laboratory capacities that are also needed for screening blood for other infectious agents.
"We need a test approach that is more proportional to risk," said Stramer
The World Health Organization has more on Zika virus.
SOURCES: Susan Stramer, Ph.D., Vice President, Scientific Affairs, American Red Cross, Gaithersburg, Md .; Evan Bloch, M.B., Ch.B., M.D., Assistant Professor of Pathology, Faculty of Medicine, Johns Hopkins University, Baltimore; May 10, 2018, New England Journal of Medicine