The U.S. Food and Drug Administration (FDA) approved a second test to detect West Nile virus (WNV) in donated blood and organs on August 28, 2007. The cobas TaqScreen WNV Test can detect the virus’s genetic material before the body’s immune system has produced antibodies to combat it. The first test to screen donated blood and organs, the Procleix WNV Assay, was approved in December 2005.
WNV is primarily transmitted to humans via mosquitoes that have fed on infected birds. It can also be spread through blood transfusions and organ transplants. In rare cases the virus has been transmitted from an infected mother to her baby during pregnancy or breastfeeding.
Most people infected by the virus are asymptomatic. In about 20% of cases, there are flulike symptoms, swollen lymph glands or a rash on the chest, abdomen and back. The symptoms can last from several days to weeks. However, about 1 in 150 people will develop serious symptoms, including convulsions, paralysis, vision loss and encephalitis, an inflammation of the brain. Neurological effects can cause permanent damage.
The virus was not detected in the United States until 1999. Since then it has spread to most states, infecting approximately one million and three million cases through 2006, according to the Centers for Disease Control and Prevention. The reported number of cases has grown from 62 in 1999 to 4,269 in 2006.
“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 of this increasingly common virus,” said Jesse L. Goodman, MD, MPH, director of the FDA’s Center for Biologics Evaluation and Research. “As a result, blood centers and hospitals now have a choice of two FDA-approved tests to screen for West Nile Virus in donated blood and organs.”
The cobas TaqScreen WNV Test is approved to detect the virus in plasma specimens from human donor of whole blood and blood components—plasma, red or white cells, and platelets—and living donor of cells, reproductive cells and other tissues. It is also for use in testing plasma specimens of organ donors when specimens are obtained while the donor’s heart is still beating. The screening test is manufactured by Roche Molecular Systems, Inc., of Pleasanton, California.
Sources: FDA news release dated August 28, 2007; CDC Web site: www.cdc.gov