Can You Get a False Positive Hsv 2 Test?
H erpes is a lifelong infection, but Lauren had it just for six tumultuous months. Or rather, she believed she did, after a request for sexually transmitted disease testing returned a positive result. But after weeks of Googling, chatting with members of online herpes forums, and reading scientific papers, she asked for a different test, which somewhen confirmed her suspicion — her herpes diagnosis was wrong.
In the half-dozen 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 arrive my leg or any kind of itch down there would just ready me off," sending her into a new flurry of enquiry, she said. "And that was simply to try to calm my ain anxiety, simply it would only actually make it worse."
Genital herpes, predominantly caused by herpes simplex virus blazon 2, is a sexually transmitted disease that's very common — ane in half-dozen people aged 14 to 49 in the United States have HSV-two, and this number goes upward with historic period. Nigh of these people, yet, don't have obvious symptoms and wouldn't know they were carriers without claret tests.
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Simply blood tests can be highly unreliable. The kind of test used to diagnose Lauren, an IgM test, has long been rejected by the Centers for Affliction Control and Prevention only is all the same used past some clinicians. Meanwhile, the CDC and the US Preventive Services Task Force concur that the about widely available canker test, called HerpeSelect, should not exist used to screen asymptomatic people because of its high chance of imitation positives: Up to one in two positive tests could be false, according to the USPSTF's most recent guidelines.
That high failure rate isn't, however, ever communicated to patients. Online forums abound with stories like Lauren's, of people who request canker tests alongside those of other STDs and are shellshocked past the results. Some doctors discourage the testing or simply don't include it in a standard STD panel without having the conversation. Just no data exists on herpes screening rates, according to Kimberly Workowski, lead author of the CDC's STD treatment guidelines — so it's difficult to say how many people could be living with the misdiagnosis.
Testing pitfalls
Next to the meandering waterways connecting Puget Sound to Seattle'south Lake Washington is the but laboratory in the earth that offers to the public the Western blot, the gilt standard test for herpes. The University of Washington Clinical Virology Laboratory provides the test to patients beyond the land, a do it began over a decade ago when information technology realized the more common tests were prone to false positives.
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The problem, said Christine Johnston, a physician and researcher at the lab, is "depression-positive" results of antibodies to HSV-2. The cutoff for a positive result on the HerpeSelect exam, manufactured by Quest Diagnostics, is one.1. A 2005 written report published in the journal BioMed Central Infectious Disease found that index values to a higher place iii.five yielded over 90 percent accuracy — but scores between 1.1 and 3.five had around a 50 percent chance of being wrong.
What's more than, scores falling but above the 1.1 cutoff had an almost 90 percent chance of being wrong.
When tests autumn between 1.1 and 3.5, more testing is necessary, said Johnston. This recommendation is also noted in the 2022 CDC Sexually Transmitted Diseases Treatment Guidelines. But some patients will never be referred for a second examination.
"I retrieve most clinicians are unaware and peradventure labs don't take this available and/or it is not straightforward to order," Johnston said of second-step tests.
Simply while her facility's Western blot is considered highly accurate, it is expensive and cumbersome to perform. Each examination costs over $200 and the Academy of Washington is the just lab that provides it.
Other confirmatory tests also exist, for instance Biokit's HSV-2 Rapid Test and Quest's own HSV-2 IgG Inhibition analysis. The latter, which adds merely $4 to the price of the HerpeSelect test, performed well in a study conducted over a decade agone. Rick Pesano, the medical director for communicable diseases at Quest, believes that with more awareness, the exam could stand up in for the Western absorb. But the test was not mentioned in the USPSTF guidelines because it withal has not been evaluated in asymptomatic individuals, according to Cindy Feltner, associate director of the RTI-UNC Evidence-based Practice Center, who helped prepare the science review for USPSTF.
"We need ameliorate diagnostic testing. That is where nosotros are stuck at this point," said Johnston. "Nosotros don't have a proficient test that'south inexpensive, loftier throughput, and reliable."
Finding out the difficult way
No good data be on how ofttimes patients with questionable positive results are actually re-tested. Until the 2022 update, CDC herpes testing guidelines had no mention of confirmatory testing for depression-positive results, said Johnston. And then patients ofttimes discovered the option not through their doctors, just through searching the web and reading online canker forums.
That was the experience of Bryan, a twoscore-year-onetime man who lives in Indiana, who wrongly believed he had herpes for about two months in 2011. The misunderstanding actually put him at higher risk, he said: During those months he considered joining the hundreds of thousands of Americans on dating sites for canker-positive people. Exclusively dating people with herpes would have increased his likelihood of contracting the virus.
The feel of YT, a 33-year-old mom who has suffered from frequent herpes symptoms over the last year, shows some other side of the testing breakdown. She believes she was given HSV by a partner who didn't realize herpes wasn't included in his previous STD tests, she told STAT. Having herpes has caused her significant emotional trauma, and has driven her to permanently swear off dating. Had her partner known his true status, she wonders if her story would have been unlike.
These kinds of stories come up out in anguished postings on internet forums and in dozens of confused calls to the UW lab each calendar week, where research coordinator Matt Seymour says some drastic patients call over and over again, unable to go the answers they need from their doctors.
"People call and say, 'I just don't know what's going on,'" he said. "We've virtually become de facto counselors."
In the absenteeism of answers
Herpes tests aren't the only ones with a risk of false positive results. False positives can occur for any test that diagnoses viral infection based on antibodies, i.e., your body's immune reaction, rather than directly detection of the virus. For similar diagnostics like HIV and hepatitis C testing, protocols automatically telephone call for a 2nd test that directly detects the virus whenever an antibody test comes back positive, said Paul Swenson, laboratory director in the department of public health of King Canton, Washington. Herpes, notwithstanding, is a particularly challenging infection to directly test for, because the virus spends most of its time hiding in nerves. Swab tests tin sometimes notice the virus during outbreaks, but this isn't an choice for people without symptoms. Thus even the Western blot relies on antibodies, and may give indeterminate results to a small number of people.
But two steps of antibody testing are all the same more reliable than 1 step; today'due south diagnostics for Lyme illness and syphilis are a two-footstep antibody testing approach, said Dr. Edward Hook, a medical epidemiologist specializing in STI screening and prevention at the Academy of Alabama, Birmingham, who questioned why such a standardized two-step approach hasn't taken firm agree for herpes.
"Some research has shown that 2-footstep testing … might improve the specificity — that is avoid false positive results for the blood test — which would be a great matter because these diagnoses create nifty anxiety and business organisation for people," he said. In a commentary accompanying the USPSTF guidelines, Hook expressed disappointment that canker testing had barely improved over the by decade.
"There is no perfect test but in that location are ways to reduce the inaccuracies and reduce the number of equivocal results and those are actively used in other diseases," he said in an interview with STAT. "But they haven't been used very aggressively for the purpose of herpes."
In the absence of cinch test advances, instruction and a lessening stigma surrounding herpes might aid, not only past reducing test-related confusion, but potentially by bringing discussion of the virus out into the mainstream, said Hook.
"There's no major herpes advancement group," he said. "People call attention to diseases that they suffer from, but people with herpes don't feel they tin can call attention to it. And that creates a lot of suffering."
Source: https://www.statnews.com/2017/01/26/flawed-herpes-testing-leads-to-false-positives/
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