SAN DIEGO (FRONTLINE MEDICAL NEWS) – Zika virus can persist in blood components for several months, long after it is no longer detectable in plasma and other body fluids, based on data reported at the annual meeting of the American Association of Blood Banks.

The presence of Zika virus in plasma declined rapidly following donation, but could be detected in red blood cells (RBCs) and whole blood for up to 3 months. In addition, the virus was also detected intermittently in peripheral blood mononuclear cells (PBMCs) at low levels after clearance from plasma.

“There was longer persistence of Zika RNA in whole blood and RBC blood components than in plasma and other body fluids. It was detected at high levels and persists for about 6 weeks,” Mars Stone, PhD said in presenting the findings .

The findings were based on 2016 data collected in Puerto Rico, which began screening blood donations for Zika virus RNA under an investigational protocol by using a nucleic acid test; they began doing so as a result of guidance from the U.S. Food and Drug Administration. Approximately 350 confirmed infected – that is, nucleic acid test positive (NAT+) – donations were detected through December 2016.

The FDA approved the cobas Zika test used in the study on October 5. Intended for use by blood collection establishments to detect Zika virus in blood donations, the test is manufactured by Roche Molecular Systems. Dr. Stone is an employee of Blood Systems Research Institute, a confirmatory laboratory for Roche.

Of the 52,942 donations collected between April 3 and Dec. 31, 352 were reactive for ZIKV RNA. Plasma from blood donors was screened by individual donation NAT for the presence of ZIKV RNA with the cobas Zika test. At an interval of between 57 and 120 days, no Zika RNA was found in 350 samples of plasma, but it was found in 38.2% (34 samples) of RBCs and 40.0% (35 samples) of whole blood.

In urine and saliva, the virus was detected in high levels at 1-2 weeks, but then rapidly waned. In semen, it was detected at high levels and persisted for about 6 weeks.

“But despite the huge epidemics in Latin America, Puerto Rico, and the other Caribbean islands, there have been no cases of transfusion-related infections linked to RBC transfusions when plasma NAT screening was negative,” said Dr. Stone. “So we are tentatively confirming that red cell–associated virus is not infectious and that plasma NAT screening is likely sufficient.”

The authors point out that RNA persistence has been reported in whole blood long after the virus cleared from plasma and therefore have raised concerns about the risk of transfusion-related viral transmission. The goal of the current study was to characterize the dynamics of infection using donors who were infected with Zika virus.

To date there are 56 donors enrolled in the study, primarily male and from Puerto Rico. Most of them are also positive for dengue fever, Dr. Stone pointed out. “The epidemic in Puerto Rico reached peak in June 2016 but has very little activity this year.”

Plasma and RBCs were collected from index donations, while blood, urine, saliva, and semen samples were collected prospectively at weeks 1, 3, 6, 12, and 24 following index donations. Blood compartments and body fluids were tested for Zika RNA by real time reverse transcription polymerase chain reaction testing, and plasma samples were tested for Zika-specific immunoglobulin M and immunoglobulin G antibodies.

In plasma, Zika virus RNA rapidly decreased after index donations but persisted for up to 3 months in RBCs and whole blood. In peripheral blood mononuclear cells, Zika virus was detected intermittently at low levels but waned by 3 months. In peripheral blood mononuclear cells, Zika RNA was detected in 5.9% (17 samples) at 121-196 days.

Among donors who entered the study while in the acute preseroconversion stage of infection, 65% developed Zika virus symptoms at 1 week post index donation, compared with 30% of donors detected after seroconversion.

The study was funded by the U.S. Department of Health & Human Services.

SOURCE: Stone M et al. AABB 2017 Abstract C9-A01AC .