What Can Cause a False Positive Herpes Test? 5 Reasons

Sadik

Herpes is a common condition, with 50-80% of American adults carrying oral herpes (HSV-1) and 11.9% having genital herpes (HSV-2). It’s a condition often associated with discomfort and stigma, which makes accurate testing crucial.

But what happens if your herpes test result is a false positive? Imagine the emotional turmoil of believing you have herpes, only to later find out the diagnosis was incorrect. This situation is more common than you might think.

So, what can cause a false positive herpes test? Let’s explore the reasons and how you can handle such a scenario.

What Can Cause a False Positive Herpes Test? 5 Common Reasons

Several potential factors can potentially contribute to incorrect herpes test results even when the person has no herpes simplex virus (HSV). Those include:

Herpes tests such as blood tests (serology) check markers in the immune system, making the results difficult to understand. These tests are more prone to false positive results in individuals with low infection risk. Blood tests like IgM tests can’t precisely differentiate between HSV-1 & HSV-2 antibodies, giving false positive results.

If it is the early stage of herpes infection (they haven’t developed a noticeable outbreak), the body of the individual might not yet release sufficient detectable antibodies. This means there can be the chances of infections but the presence of few antibodies might give false positive results.

Sometimes, laboratory errors can be the culprit. Those blunders can occur during the testing procedure such as mistakes while handling and processing of samples, contamination, or incorrect evaluation. These factors can contribute to false positive test results. 

In some cases, the test might react with proteins or antibodies from other bacteria, viruses, or conditions that may be similar to HSV. For example, an individual with Epstein-Barr virus or varicella-zoster virus due to viral infection may produce antibodies that can cross-react with Herpes simplex virus (HSV). This may lead to misinterpretation of the herpes test results.

Sometimes, certain medical conditions like autoimmune disorders can also contribute to false positive herpes test results. These conditions can impact the immune system and trigger the production of antibodies. This might interrupt the preciseness of the tests. 

What to Do In Case of a False Positive Herpes Test Result

If you receive false positive results, firstly stay calm and avoid panicking. Here’s know what you can do:

  • Request Additional Testing: Go for an additional confirmatory test, like a polymerase chain reaction (PCR) test or a second antibody test. This helps confirm the result with accuracy.

  • Consult the Doctor: Discuss your test results and all your symptoms with the doctor. They can better help with the proper guidance toward the appropriate diagnosis.

  • Consider Your Risk Factors: If you have any sexual history & risk factors that can raise the risk of actual exposure to HSV, speak about it to your doctor.

  • Look for a Second Opinion: If you are still unsure or not completely satisfied with the given explanation regarding the result, go for a second opinion for more clarity.

  • Understand the Test Limits: Remember false positive results are common, particularly with antibody blood tests. So, always discuss the different tests before deciding. 

READ ALSO Understanding STD Online Testing

FDA Recommendations 

The U.S. Food and Drug Administration (FDA) recommends all the healthcare providers & lab staff to be aware of the following things to lower the chances of false reactive results:   

  • Check the CDC guidelines before advising HSV-2 blood tests.

  • Be mindful that false positive results can occur.  

  • Guide the people regarding the drawbacks of available tests before getting HSV-2 serologic tests. 

  • Perform additional confirmatory testing like Biokit or Western blot tests for false positive results as given in the labeling of the test and according to professional guidelines.

Why Do False Positives Happen More Often?

False positives happen more often due to the early blood test and low risk of herpes infection. The test results are common, giving half of the incorrect results. Serology (antibody) Tests like the HerpeSelect test can produce around 50% incorrect false positives. Hence, better useful for detecting past herpes infections even in the absence of symptoms.

The inaccuracy is primarily because of “borderline positive” readings, which fall close to the standard test’s cutoff for a positive diagnosis. This can lead to misinterpretation of the result. 

Comparing Tests for Genital Herpes With or Without Symptoms










Scenario

Testing with Symptoms

Testing without Symptoms

Type of Test

Commonly PCR, serology (antibody test), and viral culture are used.

Serology is often utilized to identify past herpes infections.

Reliability

Higher accuracy as symptoms like sores are clearly evident.

Less reliable, as there are no active herpes outbreaks, meaning detectable antibodies may not be available yet.

Purpose of Testing

To confirm the presence of active herpes infection and detect the specific HSV type.

To know about past herpes exposure.

Timing

Immediate or at the time of herpes outbreak for precise diagnosis.

Can be conducted anytime, even after years of potential herpes exposure.

Risk of False Results

Lower risk as the herpes virus is actively disappearing.

Higher risk because of the lack of active virus.

Symptoms to Check

Painful sores, blisters, or itchiness in genital areas.

No symptoms, or uncertainty about past herpes exposure.

When Should You Consider a Herpes Test?

Get tested for herpes if you:

  • experience any genital symptoms that can be associated with herpes.

  • have or had a sex partner living with genital herpes.

  • have herpes symptoms examined by your doctor but still need a confirmatory test.

Testing allows the doctors to understand what can happen in the future and what treatment plan can help. Medications can help reduce symptoms. In addition, doctors can guide you on how to prevent the risk of herpes transmission to your partner.

Moreover, herpes testing is not recommended for individuals with no symptoms in certain situations. That’s because of the limitation of the blood tests and the chances of incorrect results. The possibility of false herpes test results is higher in people with low infection risk.

READ ALSO Step-by-Step Guide: How to Get Tested for Herpes

Can Herpes be Actually Misdiagnosed?

Yes, misdiagnosis of herpes can occur due to the following reasons:

Conditions such as genital warts, fungal infections, or ingrown hairs can imitate the symptoms of herpes, causing confusion.

Lab errors, cross-reactivity with other present viral infections, or incorrect sample collection can contribute to a false positive herpes test result.

Some individuals may not show noticeable herpes symptoms, resulting in missed diagnosis and associating those symptoms with other issues.


The first herpes outbreak may be mistaken for other conditions as the sores at an early stage might be different in appearance or less extreme.

People who also are living with other infections such as sexually transmitted infections (STIs) might result in overlapping symptoms, making the diagnosis complicated.

Too early or too late testing during the herpes infection cycle can impact the results’ preciseness, especially in the antibody blood tests. 

Final Thoughts

For those wondering, what can cause a false positive herpes test result, well, factors like test types, lab errors, cross-reactivity, or other health issues can contribute to it. Though they are not common, they can be a possibility. Hence, understanding the potential reasons behind such a misinterpretation and seeking confirmatory tests is crucial if you are unsure.

Remember that do not panic in case you get positive results. See a doctor to ensure a precise diagnosis. Stay informed & take proactive measures for good health!

READ ALSO How is Herpes Transmitted Non Sexually? 4 Unknown Ways

Frequently Asked Questions

Can a yeast infection cause a false positive herpes test?

No, there is no possibility. Though both share the same symptoms in genital areas, yeast infection doesn’t interrupt the test results.

What can be mistaken for herpes in a blood test?

The conditions that mimic herpes include genital warts (HPV), syphilis, bacterial vaginosis, bug bites, ingrown hairs, irritation from shaving, and hemorrhoids.

Can Bacterial Vaginosis (BV) cause a positive herpes culture test result?

Yes, there are increased chances of herpes infection due to BV as it can change the cytokine milieu in the genital tract.

Can HPV contribute to a false positive test result for herpes?

No, it can’t as herpes is caused by herpes simplex virus (HSV) and HPV by over 200 Human papillomavirus (HPV) viruses.

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