BEIJING, Aug. 31 (Xinhuanet) -- The U.S. Food and Drug Administration has approved an automated West Nile virus test developed by Roche Molecular Systems Inc. of F. Hoffmann-La Roche Ltd. the company said late Tuesday.

    Few people infected with the virus show signs of the disease but about 1 in 150 to 1 in 350 infected people will develop serious symptoms, including encephalitis, an inflammation of the brain.

    The virus has been particularly virulent this year, the FDA said in a statement about the approval. In California this year, 164 human cases of the virus have been reported so far -- eight in Sacramento County and one in Yolo County. Last year, 278 human cases of the virus were reported statewide.

    It is the second FDA-approved test for detecting the virus in blood and organs. The first fully automated test was developed by San Diego's Gen-Probe Inc. and marketed by Emeryville's Novartis Vaccines and Diagnostics Inc., part of Novartis AG.

    Both tests are able to detect the genetic material of the virus itself early in the infection.

    Since 1999, when the virus first appeared in the United States, the reported number of human cases of serious West Nile virus in the United States has grown steadily from 62 in 1999 to 4,269 in 2006, according to the FDA.

    (Agencies)