Herpes Virus (HSV)

The following section outlines some key details about the herpes virus, and herpes virus testing.

Background Information About Herpes

What is herpes?

Herpes is a virus that is passed to people through sexual and non-sexual contact. In many cases, herpes transmission occurs in childhood, either from a parent to a child (sharing a drink or a kiss when a family member has an active cold sore). It is also commonly passed through sexual contact, including kissing.

What is the difference between HSV-1 and HSV-2?

There are two commonly discussed herpes viruses - HSV-1 and HSV-2. Either one can cause genital herpes or cold sores. The terms 'genital' and 'oral' refer to the sites of infection and not the types. Historically, people with genital herpes outbreaks often tested positive for HSV-2, and people with cold sores tested positive for HSV-1. However, a larger number of genital herpes infections are caused by HSV-1. HSV-2 seems to cause a higher number of symptomatic outbreaks than HSV-1, but both stains are nearly identical.

How common is herpes?

The herpes virus is very common - more common than most people think. A 2003 study completed in Ontario of 1500 adults found that by the age of 44, approximately 70% of adults tested positive for HSV-1, and 20% were positive for HSV-2. By age 25, approximately 40-50% of adults have tested positive for HSV-1.

What are the symptoms of a herpes outbreak?

Herpes can vary in severity between very mild outbreaks that are barely noticeable, and other others that are very painful and debilitating. Symptoms include burning and tingling, a blistering rash, fever and muscle/body aches, local lymph node swelling, painful urination, and in women, changes in vaginal discharge.

Herpes Testing

What is the best way to test for herpes?

The ideal method to test for herpes is a Viral PCR (DNA) swab of a rash or area where a doctor thinks you’re having an outbreak. Testing is time sensitive. Ideally, an area should be swabbed within 72 hours of getting symptoms. If you swab too late, you can actually get a false negative result (this means you actually had a herpes outbreak but because you swabbed too late, it states no herpes is present).

Can a blood test tell me if I have genital herpes?

A herpes blood test cannot tell you if you have genital herpes. It only indicates you have been infected with either one or both strains of the herpes virus. The infection sites may be oral, genital or both if you are positive for both strains. The only way to determine if you have genital herpes is a swab of the site at the time of an outbreak, or based on a visual diagnosis by a health care provider.

How long does it take to develop an IgG titre after a new herpes infection?

Current medical literature guides 21-42 days as the time to develop an IgG response, though most people show levels on days 21-28. However, Public Health Ontario reports it can take 3-6 months for a small percentage of people to show an IgG level.

What are 5 reasons I shouldn't test for herpes?
  • Has a high false positive rate

    These tests carry a high false positive rate. People test positive, but 1-10% of people have never had a herpes infection. This makes someone think they have herpes, when they don’t.

  • Doesn’t identify the location of the infection

    Having evidence of a herpes infection on bloodwork doesn’t tell you where you were infected (oral or genital). Testing positive for HSV-2 doesn’t mean you have genital herpes. For example, you might have an oral HSV-2 infection.

  • Doesn’t confirm if a previous rash was herpes

    Having an antibody positive doesn’t usually clarify if the genital rash or rash around your lips that you experienced before was herpes. It may suggest it, but no doctor can confirm the diagnosis based on a positive blood result. Doctors order testing to provide answers, and you will not get a definitive answer from a blood test about whether a previous rash was herpes.

  • Can have a false negative result

    In some instances, people have swabs that have confirmed herpes, but test negative on the antibody test. This provides false reassurance and makes someone think they don’t have genital herpes, when they do.

  • Causes anxiety and stress

    Because of the high prevalence of HSV 1, more than 50% of people test positive. Having a positive antibody test creates unnecessary anxiety and makes conversations with future sexual partners difficult. If you chose to get a herpes blood test, have a positive herpes antibody that is likely related to cold sores, are you prepared to notify every future sexual partner you have antibodies to herpes, but no symptoms? Are you well-versed in explaining the nuances of herpes bloodwork, false positive rates and the differences between serotypes to future sexual partners?

When might a herpes blood test be useful?

Scenario A

Your partner has genital or oral herpes. They have a swab test that confirms either HSV 1 or HSV 2. Type-specific blood testing is useful for you because if you have antibodies to the same strain of herpes (i.e. you are both ‘sero-concordant’), then you cannot get genital or oral herpes from them if you have unprotected sex. Your partner, therefore, does not need to be on suppressive anti-viral medication or use condoms to prevent HSV transmission.

Caveat: if your blood test is a false positive result, and you haven’t actually had herpes exposure and you use this information to have unprotected sex with your partner with genital herpes, you can actually get a genital herpes infection. This is a low-probability event, but possible.

Scenario B

You have a history of genital herpes or cold sores that is confirmed by a swab or bloodwork. You’re thinking about going on a daily anti-viral medication to reduce the likelihood of your partner contracting herpes. Your partner can get tested to see if they’re immune to the same strain you have. If they’re immune, then you don’t need to be on anti-viral medication.

Caveat: if your partner’s blood test is a false positive result, and they haven’t actually had herpes exposure and you use this information to have unprotected sex with your partner, they can get a genital herpes infection. This is a low-probability event, but possible.

Scenario C

You have a rash that keeps showing up around your lips or genital area. The doctors you see have done multiple swabs and tell you they think you have herpes, but the swabs keep coming back negative. Maybe you show up too late for the swab, or maybe the sample was inadequate. You can obtain type-specific blood testing. If you’re positive, it suggests that the rash you have may have been herpes (no doctor can give you a 100% guarantee that the virus is the cause, however). However, if your bloodwork is negative, the rash is not herpes.

Caveat: herpes antibodies can take 3-6 months to develop; if your rash is new, you need to delay your bloodwork for 6 months after the start of your rash for a clearer answer.

Scenario D

You had a confirmed case of herpes exposure through protected or unprotected sex within the last 7-14 days. You currently have no symptoms. Completing bloodwork establishes your baseline serological status (i.e. it identifies if you have antibodies to the herpes virus). It takes on average 21-42 days to form IgG HSV antibodies, with most people developing IgG antibodies 21-28 days post-exposure to the herpes virus.

You repeat testing in 180 days (as there can be a theoretical delay of up to 6 months to develop IgG antibodies). If there is no change in your IgG status, that indicates you do not have a new herpes infection.

Caveat: If your baseline HSV test is positive for one of the two strains, it is possible that you are positive unrelated to recent exposure but an infection earlier in life.

Are blood tests for herpes type specific?

A type-specific blood test is a test that tells us what strain of herpes infection you have. Our herpes testing is done through Ontario Public Health Labs. Having antibodies to HSV-1 and HSV-2 means you have been infected somewhere on your body (face, eyes, arms, genitals, etc). It doesn’t tell us where. The virus is dormant, waiting to be reactivated in the form of a herpes outbreak.

How long does it take for my herpes test to turn positive?

Completing a swab of a herpes outbreak can provide an immediate answer. Blood tests can take between 3-6 months to turn positive after exposure to herpes. Testing too early can provide false negative test result.

Can I get an IgG titre?

Currently, public health laboratories DO NOT report an IgG titre like most American laboratories. The lab only reports the test as ‘reactive’ or ‘non-reactive’. We’ve called Public Health and asked for a IgG titre as many patients have requested it, but they do not provide such a reading.

What kind of lab test does Public Health use?

Our Ontario Public Health Laboratories use the Liaison HSV 1 and Liaison HSV Type 2 Specific IgG Assay - it has a sensitivity of 96.9-98.9% (misses 1.1-3.1% of infections) and a specificity of 91.3%-96.8% (false positive rate of 3.2% - 9.7%). The test result can be negative early in the course of an infection, which is why we encourage repeat testing if you are symptomatic at the 6-month point.

My herpes report says 'indeterminate'. What does this mean?

If you have an indeterminate herpes antibody test and have had symptoms of cold sores or a genital outbreak recently, it may represent an 'early' antibody response that will become positive with a repeat test in 12 weeks. A repeat test is encouraged for certainty if you have had symptoms. If you have not had any outbreaks in the past, or any known exposures it can also represent a false positive and we don't recommend a repeat test at this time.

What type of swab is needed to diagnose HSV?

Labs can process a 'Copan Viral UTM' swab that looks specifically for the DNA of HSV-1 and HSV-2. This viral PCR swab is completed by swabbing the location where a rash has erupted (i.e. a blister on the lip or genital area).

Despite our requests, laboratories in Ontario do not carry these specific swabs. The only way to obtain a viral PCR swab of a rash is to visit a doctor's office when the outbreak is occurring. It's important the doctor uses the correct swab type, as swabs completed for gonorrhea/chlamydia are not processed by the lab for HSV-1 and HSV-2 DNA testing.

Swabs currently supplied by Life Labs for self-swabbing are limited to 'Charcoal Swabs' that test for Bacterial Vaginosis and Yeast infections.

Herpes Transmission

How can I get genital herpes?

A person can contract HSV by receiving oral sex, having genital-genital contact, or using sex toys with someone with either HSV-1 or HSV-2.

  • If your partner has HSV-1 cold sores and performs oral sex on you, you can contract genital HSV-1 herpes.

  • If your partner has HSV-2 genital herpes and you have genital-genital contact/sex, you can contract genital HSV-2 herpes.

  • If your partner has HSV-2 genital herpes and you perform oral sex, you can contract oral HSV-2 herpes.

How can I prevent herpes?

Condoms, if used consistently and correctly will reduce, but will not eliminate the risk of HSV transmission or acquisition. They need to protect or completely cover the infected area or the area of potential exposure. They can also be used as a barrier for oral-genital sex if your partner has a history of cold sores.

Valacyclovir 500 mg ingested daily by a patient with genital HSV-2 infection has been shown to reduce transmission to a susceptible heterosexual partner by 48%. The effect of condoms and suppressive valacyclovir may be additive.

Does every herpes outbreak cause symptoms?

Most people who have genital herpes don't know they have the infection because they have mild, short-lived, or no symptoms at all, or they think the symptoms are due to another condition (e.g., yeast infection, boils, bug bites, friction burns). Many people who test positive for the herpes virus acquired it in childhood and cannot remember ever having symptoms.

I’ve have had cold sores, but I have never had a genital outbreak. Can I still get genital herpes?

Yes. Contracting genital herpes requires exposure to the virus through bodily fluids. If you have had cold sores (of one HSV strain) and have sex with someone and are exposed in the genital area (of different HSV strain), you can have a genital herpes outbreak. Herpes antibodies are only protective against the same strain of herpes.

Do I have to have symptoms to transmit or recieve herpes?

Herpes transmission most easily occurs when people have symptoms of an outbreak - this includes a visible rash or when they have associated symptoms like burning, tingling and pain. It is becoming increasingly well-understood that most HSV transmission occurs without symptoms. Recent studies have found that almost 75% of herpes outbreaks can occur without symptoms, and approximately 50% of these outbreaks last less than 12 hours. This is known as asymptomatic shedding and is often how many people contract herpes, either from protected or unprotected contact. In most cases, a partner may not even know they have herpes.

I tested positive for HSV 1 or HSV 2. Do I need to disclose my status to partners?

Having a positive result for herpes does not legally necessitate disclosure to future partners, as is required for some conditions like HIV. However, open discussion with a partner is encouraged so both partners can make informed decisions about testing, treatment and safe-sex practices.

How long can herpes survive on sex toys without cleaning them?

The herpes virus can survive outside the body on surfaces for a few hours to up to 8 weeks. The virus is, however, easily inactivated by keeping it at temperatures >56°C for 30 min, microwaving for more than 4 minutes, or exposure to a pH of < 4 (vinegar or lemon juice).

Managing Herpes Outbreaks

How many outbreaks will I get?

Approximately 90% of individuals with HSV-2 have another outbreak within their first year. The average number of repeat outbreaks in the 1st year after infection is between four to five. Recurrent episodes decrease in frequency over the 1st five years after the initial infection. Recurrent episodes are also much milder, and in many cases produce few symptoms. There is no way to predict how many episodes a person will get. It’s reasonable to assume less than five in an average year.

What causes herpes outbreaks?

Herpes outbreaks can occur during periods of stress and illness. Examples include when a person has a recent illness, like the flu or cold, or following surgery or a medical procedure. Doctors can provide anti-viral medication to shorten and improve the severity of symptoms during an outbreak.

Interpreting Your Results

Should I get checked for herpes?

We do not recommend routine testing for herpes virus antibodies. If you fall into Scenario A, B, or C above it may be useful to be tested.

I tested 'reactive' for HSV 1 or HSV 2. Does this mean I have genital herpes or cold sores?

This means you’ve been infected with that particular strain of herpes. Testing positive for HSV-1 or HSV-2 doesn’t tell us whether you have genital herpes or cold sores. It tells us you’ve been infected somewhere on your body, and the virus is dormant waiting to activate. In some cases, you may never have a symptomatic outbreak in your entire lifetime. If you’ve had cold sores, it is likely that’s where your infection is.

I tested positive for HSV 1 or HSV 2. Should I start medication now?

Medication for the herpes virus is only suggested in two scenarios.

Scenario A: You are experiencing a genital or oral outbreak. Medications can help control your symptoms during the outbreak.

Scenario B: Your partner is sero-negative (they’ve tested for the virus on bloodwork) and you want to reduce asymptomatic transmission of the virus to your partner. You can stay on a daily suppressive dose of medication.


I have frequent herpes outbreaks. Should I be on a suppressive dose?

Daily anti-viral medication has been shown to reduce the number of symptomatic outbreaks by 70-80% and reduce the severity of breakthrough outbreaks (outbreaks that occur while you are on suppressive therapy). Taking daily medication can be onerous, so we only recommend suppressive therapy if the severity of outbreaks and frequency is having a significant impact on your quality of life. For some people, that might mean more than 10 outbreaks in a year.

I’m currently on a suppressive dose but still having outbreaks. What should I do?

In some cases, the dose of the medication may need to be adjusted or you can try a different anti-viral medication. As an example, for someone on Valacyclovir 500mg once daily, we can try 1000mg daily instead.

Lab testing is not routinely required while on suppressive anti-viral therapy because adverse reactions are rare, outside of high-risk groups (individuals with kidney disease, a kidney transplant, or AIDS).

Can herpes can be cured?

The herpes virus cannot be cured, but we have very effective antiviral medication to treat an outbreak or prevent transmission. Some people never experience an outbreak in their lifetime, and others may only experience an outbreak once every few years. Others may have an outbreak more frequently.

Miscellaneous Questions

My partner has a new genital herpes outbreak. Could I have given my partner herpes if I have never had a herpes outbreak?

Yes, it is possible. Herpes transmission can occur when an individual does not have symptoms. Transmission can occur under the following circumstances

If you do not have symptoms of genital herpes but actually have it, and your partner has never been exposed to that strain, s/he will develop a herpes outbreak through sexual contact with you.

If you have

Why is HSV (Herpes Simplex Virus) testing not covered by OHIP?

HSV (Herpes Simplex Virus) testing is not covered by OHIP (Ontario Health Insurance Plan) because it is typically considered a non-essential or elective test. OHIP generally covers tests that are deemed medically necessary by a healthcare provider for diagnosing or managing a patient's health condition. HSV testing is often categorized as a screening test that may not meet the criteria for medical necessity under OHIP guidelines. If you require HSV testing, it may need to be paid for out-of-pocket or through private insurance.

Additional Resources

Order HSV testing or medication through TeleTest

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