To screen for and diagnose infection with a herpes simplex virus (HSV)
- When you have symptoms of an eye, oral or genital herpes infection, which are usually accompanied by a rash consisting of small blisters or sores; itching or tingling in the affected area is common.
- When you have certain risk factors, such as having a sex partner with herpes
- When you have symptoms of viral meningitis such as fever, persistent headache, stiff neck
- A pregnant woman who has been diagnosed with herpes may be monitored regularly prior to delivery.
- A newborn from a mother who has active blisters may be tested soon after delivery to assess the risk of transmission from mother to baby during delivery.
- A newborn may also be tested soon after delivery when the baby shows signs of HSV infection, such as meningitis or skin lesions that could be caused by the herpes virus.
A healthcare practitioner uses a swab or spatula to collect a sample from a blister or sore in the affected area. A sample of cerebrospinal fluid (CSF) may be collected using a lumbar puncture (spinal tap) when meningitis or encephalitis is suspected. For HSV antibody testing, a blood sample is obtained by inserting a needle into a vein.
Herpes is a common viral infection caused by the herpes simplex virus (HSV). The virus exists as two main types, HSV-1 and HSV-2. HSV testing identifies the presence of the virus in a sample from a blister, sore or fluid to diagnose an active herpes infection or testing detects antibodies in the blood to determine previous exposure to herpes.
Both HSV-1 and HSV-2 are contagious and periodically cause small fever blisters (vesicles) that break to form open lesions.
- HSV-1 primarily causes blisters or "cold sores" around the mouth (non-genital sites).
- HSV-2 usually causes lesions around the genital area.
However, both HSV-1 and HSV-2 can affect either the oral or genital areas.
The herpes simplex virus can be passed from person-to-person through skin contact while the sores are open and healing and sometimes when there are no visible sores. HSV-2 is the type most often spread during sex, but HSV-1 may also infect the genital area during oral sex.
Most people who have HSV-2 are unaware they are infected because signs and symptoms may be mild and go unnoticed.
- When symptoms do appear, they may begin as painful blisters at the site of infection, usually within two weeks after infection.
- The blisters can appear around the mouth, in the vaginal area, on the penis, around the anus, or on the buttocks or thighs.
- The blisters generally heal within two to four weeks.
- This primary episode can include a second outbreak of blisters and even flu-like symptoms such as fever and swollen glands.
- However, not everyone develops blisters and sometimes symptoms are so mild that they are unnoticeable or mistaken for something else, such as insect bites or a rash.
Once you are infected and the initial infection resolves, the virus remains in your body in a latent form for the rest of your life. During periods of stress or illness, the virus may reactivate and you may have periodic outbreaks. People with weakened immune systems, such as those with HIV/AIDS or those who have had an organ transplant, may have more frequent and serious outbreaks of HSV.
There is no cure for herpes, but antiviral medications such as acyclovir, famciclovir and valacyclovir can suppress outbreaks and shorten the duration of symptoms and active shedding of the virus.
Rarely, the virus can cause infections in newborns (neonatal herpes) when a mother transmits the virus to her baby during a vaginal delivery. Neonatal herpes symptoms appear during the first month of life. If left untreated, herpes can cause long-term health problems in the baby and can be life-threatening. A pregnant woman who has been diagnosed with herpes may be monitored regularly prior to delivery to detect a reactivation of her infection.
A HSV infection can spread to the brain, causing encephalitis. This illness can be fatal or cause serious, permanent neurological problems in those who survive.
Herpes may be tested a few different ways:
Direct detection of the virus
The preferred methods of testing for the virus in people with active blisters or sores are the herpes culture and HSV PCR testing. PCR testing is the preferred method if encephalitis or neonatal herpes are suspected.
- HSV DNA PCR (NAAT)—this method detects HSV genetic material in a sample from the blister, blood, or other fluid, such as spinal fluid. PCR can detect the virus as well as identify the type of herpes virus (HSV-1 or HSV-2). This method is more sensitive than culture and is becoming more widely available.
- Herpes culture—a sample of fluid is collected from an open sore using a swab and cultured. If the culture is positive, the virus can be further identified as HSV-1 or HSV-2.
HSV antibody (serologic) testing detects immune proteins called immunoglobulin G (IgG) in your blood that the body produces in response to a herpes infection. HSV antibody testing can detect both HSV-1 and HSV-2 antibodies as well as differentiate between them.
How is the test used?
Herpes testing may be used a few different ways:
- Herpes simplex virus (HSV) PCR testing or culture may be used to diagnose an active herpes infection if you have signs and symptoms, such as genital sores or encephalitis.
- HSV PCR is the preferred test to diagnose newborns suspected of having neonatal herpes, a rare but serious condition in which herpes is contracted during vaginal birth.
- HSV antibody testing may be used to determine whether you have been exposed to HSV in the past. This may be helpful in screening certain populations, such as potential organ transplant recipients. It may also be useful for pregnant women to help determine the risk of them passing an HSV-2 infection to their baby.
- PCR and antibody testing may be used to distinguish between HSV-1 and HSV-2 infections.
The U.S. Centers for Disease Control and Prevention (CDC) does not recommend screening for herpes in the general population, but it may be helpful in some cases, such as:
- If you have signs and symptoms, such as genital sores that may be related to herpes
- If you have or had a sex partner with genital herpes
- If you would like to have a complete exam for sexually transmitted diseases (STDs), especially if you have multiple sex partners; if this is the case, you should discuss STD testing with your healthcare practitioner.
When is it ordered?
- Severe persistent headache
- A stiff neck
- Sensitivity to light
- Mental changes
Prenatal and newborn testing
- A pregnant woman who has been diagnosed with herpes may be monitored regularly prior to delivery to detect a reactivation of her infection.
- A baby born to a mother who has active lesions during delivery may be tested before symptoms appear to assess whether the baby was exposed to HSV during delivery.
- A mother and newborn may be tested for HSV soon after delivery when a baby shows signs of HSV infection, such as meningitis or skin lesions that could be caused by the herpes virus.
HSV antibody testing may be done when your healthcare practitioner wants to determine if you have been exposed to HSV in the past.
What does the test result mean?
Direct detection of the virus
- A positive HSV DNA (PCR) test or culture indicates that you have an active herpes infection, and the result may indicate if it is HSV-1 or HSV-2.
- A negative PCR test or culture indicates that the herpes simplex virus was not detected, but this does not definitely rule out an infection. False negatives can occur if there is not enough active virus in the sample. This may happen if the lesion is cultured more than 48 hours after the symptoms appear. If suspicion of herpes remains high, repeat testing may be done.
Antibody blood tests
- A positive HSV-1 or HSV-2 IgG antibody test means antibodies are present in your blood, which means you have had an infection in the past even if you haven't noticed any symptoms. The type of antibody detected indicates the type of HSV infection.
- Negative HSV antibody results mean that it is unlikely that you have been exposed to HSV or it may mean that your body has not had time to begin producing HSV antibodies.
Can herpes simplex virus cause serious infections?
Yes. The most serious, or life-threatening, HSV infections can occur in newborns who are infected during birth and in individuals with weakened immune systems (immunocompromised), such as organ transplant recipients and people with HIV/AIDS. Neonatal herpes is a serious condition, but also very rare. While 25-30% of pregnant women have genital herpes, less than 0.1% of babies born in the U.S. each year get neonatal herpes. This means that most women with genital herpes give birth to healthy babies.
HSV lesions (vesicles) tend to be more extensive and persist longer in newborns and immunocompromised people than in individuals who have healthy immune systems.
How can herpes be prevented?
Oral herpes (mouth sores, skin lesions in non-genital sites) can't be prevented. Exposure occurs during everyday life.
The most reliable ways to avoid genital infection with herpes or any sexually transmitted disease (STD) are to abstain from oral, vaginal, and anal sex or to be in a long-term, mutually monogamous relationship with an uninfected partner. People who are sexually active should correctly and consistently use condoms to reduce the risk of infection with herpes and other STDs. If sex toys are used, use a condom on the toy. A fresh, unused condom should be used with each different person or location (mouth, anal, vaginal areas). The toy should also be cleaned between uses with different people and/or locations.
Are there other types of herpes viruses besides HSV-1 and HSV-2?
Yes. There are over 25 viruses in the herpes family and at least 8 types that infect humans. These include herpes simplex virus types 1 and 2 discussed in this article as well as varicella zoster virus (VZV, HHV-3), associated with chickenpox and shingles, Epstein Barr virus (EBV, HHV-4), which can cause infectious mononucleosis, cytomegalovirus (CMV, HHV-5), human herpes virus 6 (HHV-6) and human herpes virus 7 (HHV-7), both associated with roseola in young children, and human herpes virus 8 (HHV-8), which has been found in tumors in people with Kaposi's sarcoma (KS). KS primarily affects people with weakened immune systems, such as those with HIV/AIDS and organ transplant recipients.
How long does it take to get results?
Where can I get tested?
How is herpes treated?
Herpes cannot be cured, but it can be managed. Medications are available that can prevent or shorten the duration of herpes outbreaks. There is a medicine that you can take on a daily basis that can help prevent outbreaks and also lower your risk of spreading the virus to others. Talk to your healthcare provider about your options. Antiviral medications such as acyclovir, famciclovir and valacyclovir can suppress outbreaks and shorten the duration of symptoms and active shedding of virus.
Should I tell my partner that I have herpes?
Is there anything else I should know?
Herpes can make people more susceptible to HIV infection. The skin lesions give other sexually transmitted diseases (STDs), including HIV, openings for entering the body. Likewise, it can make HIV-infected individuals more infectious. Infection with HSV can also increase HIV viral load. HSV-2 infection is a significant opportunistic infection in HIV-infected individuals due to immune system deficiencies; up to 90% of HIV-infected individuals are co-infected with HSV-2.