The Food and Drug Administration Approves Second West Nile Virus Screening Test for Donated Blood and Organs

Abstract

The US Food and Drug Administration (FDA) announced approval on August 28, 2007, of a second test for detection of West Nile virus (WNV) in blood and organs. The cobas TaqScreen WNV test is an automated test that is able to detect viral RNA early during infection. Such nucleic acid testing improves blood and organ safety, detecting whether donated blood and organs have been infected, even before the donor’s immune system has begun to produce antibodies against the virus. Most often, WNV is transmitted to humans by mosquitoes; however, this pathogen can also be transmitted by blood transfusion or organ transplantation from infected donors. Although WNV infection is common in Africa, Asia, and the Middle East, it did not appear in the United States until 1999. Since then, WNV has become endemic in most of this country, with from 1–3 million cases reported between 1999 and 2006, according to the Centers for Disease Control and Prevention (CDC). “This action is the culmination of the dedicated efforts of FDA, our sister agencies, blood establishments, and manufacturers to bring donor screening tests to market for this increasingly common virus,” said Dr Jesse L. Goodman, director of the FDA’s Center for Biologics Evaluation and Research. “As a result, blood centers and hospitals now have a choice of 2 FDA approved tests to screen for West Nile Virus in donated blood and organs.” Most people infected with WNV show no signs of the disease but about 1 in 150 to 1 in 350 infected people develop serious symptoms, including encephalitis. Since introduction of the virus, the reported number of human cases of serious WNV in the United States has grown steadily from 62 in 1999 to 4269 in 2006. WNV has been particularly virulent this year. Although it is still early in the WNV season, 58 blood donors who are potentially positive for the virus have been reported to the CDC as of August 21, 2007. The cobas TaqScreen WNV test is approved for detection of the virus in plasma specimens from human donors of whole blood and blood components (plasma, red or white cells, platelets) and living donors of cells, reproductive cells, and other tissues. It is also intended for use in testing plasma specimens of organ donors when specimens are obtained while the donor’s organs are still viable. The test is not intended for use on samples of cord blood or as an aid in the diagnosis of WNV infection (Figure 1). Approval comes as the FDA is preparing guidance on the use of licensed WNV screening tests for blood donors. The test is manufactured by Roche Molecular Systems Inc (Pleasanton, CA). In December 2005, Procleix WNV Assay, from Gen-Probe Inc (San Diego, CA), became the first FDA-approved WNV genetic test for blood and organs.