U.S. Labs Using Outdated Genital Herpes Tests, Produce False Positives, Report Says
Many laboratories in the US are using outdated blood tests that often produce false-positive results to detect genital herpes, according to a report published in the August issue of the… American Journal of Obstetrics & Gynecology, Reuters Health reports. Zane Brown and Rhoda Ashley Morrow of the University of Washington School of Medicine examined data obtained through the test proficiency program of the College of American Pathologists. CAP sent to 172 laboratories a blood sample that was positive for antibodies of herpes simplex virus type 1, the form of herpes that causes common cold sores, and negative for herpes simplex virus type 2, which causes genital herpes. Nearly all of the labs correctly detected HSV-1 antibodies in the sample, but more than half of the labs inaccurately reported that the sample was positive for HSV-2 antibodies.
According to the report, only blood tests based on a protein called glycoprotein G are proven to be effective in distinguishing and identifying antibodies to the herpes viruses. Of the 94 of labs that identified which type of test they used, all 44 sites using a glycoprotein G-based test accurately reported the sample did not contain HSV-2 antibodies. Labs using other types of tests showed false-positive rates between 14% and 88% for HSV-2, the report says. The authors recommend that labs use only the approved, accurate glycoprotein G-based blood tests to screen for type-specific herpes in order to reduce the spread of the virus. About one-third of U.S. adults have genital herpes, but only about 10% are aware they are infected, according to Brown (Rauscher, Reuters Health, 8/29).