What’s more, scores falling just above the 1.1 cutoff had an almost 90 percent chance of being wrong. A 2005 study published in the journal BioMed Central Infectious Disease found that index values above 3.5 yielded over 90 percent accuracy - but scores between 1.1 and 3.5 had around a 50 percent chance of being wrong. The cutoff for a positive result on the HerpeSelect test, manufactured by Quest Diagnostics, is 1.1. The problem, said Christine Johnston, a physician and researcher at the lab, is “low-positive” results of antibodies to HSV-2. The University of Washington Clinical Virology Laboratory provides the test to patients across the country, a practice it began over a decade ago when it realized the more common tests were prone to false positives. Next to the meandering waterways connecting Puget Sound to Seattle’s Lake Washington is the only laboratory in the world that offers to the public the Western blot, the gold standard test for herpes. Meanwhile, the CDC and the US Preventive Services Task Force concur that the most widely available herpes test, called HerpeSelect, should not be used to screen asymptomatic people because of its high risk of false positives: Up to 1 in 2 positive tests could be false, according to the USPSTF’s most recent guidelines. The kind of test used to diagnose Lauren, an IgM test, has long been rejected by the Centers for Disease Control and Prevention but is still used by some clinicians. Most of these people, however, don’t have obvious symptoms and wouldn’t know they were carriers without blood tests.īut blood tests can be highly unreliable. Genital herpes, predominantly caused by herpes simplex virus type 2, is a sexually transmitted disease that’s very common - 1 in 6 people aged 14 to 49 in the United States have HSV-2, and this number goes up with age. “And that was just to try to calm my own anxiety, but it would only really make it worse.” In the six months that passed between the tests, the mistake led her to keep a romance at bay and left her anxiously patrolling her health.“Every tingle I would get in my leg or any kind of itch down there would just set me off,” sending her into a new flurry of research, she said. But after weeks of Googling, chatting with members of online herpes forums, and reading scientific papers, she asked for a different test, which eventually confirmed her suspicion - her herpes diagnosis was wrong. Or rather, she believed she did, after a request for sexually transmitted disease testing returned a positive result. Herpes is a lifelong infection, but Lauren had it only for six tumultuous months.
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