Genital Herpes Causes: HSV-1 and HSV-2

Two viruses, herpes simplex 1 (HSV-1) and herpes simplex 2 (HSV-2), can cause a genital herpes infection. The two viruses are closely related but not identical.

HSV-1 is also the most common cause of oral herpes, or cold sores.

While a diagnosis of genital herpes is often emotionally upsetting, “Having herpes is generally not the end of the world,” says H. Hunter Handsfield, MD, a professor emeritus at the University of Washington Center for AIDS and STD in Seattle.

“It can be managed within a normal life without the impact that people are afraid of when they haven’t got the disease,” Dr. Handsfield says.

An HSV-2 infection is sexually transmitted and is associated with a 2 to 3 times risk of someone contracting HIV if exposed. It’s recommended that anyone with genital herpes be tested for HIV. (1,2)

Infection with either HSV-1 or HSV-2 is remarkably common. In fact, the majority of people in the world are infected with one of the two herpesviruses, but not everyone has symptoms.

About 1 in every 6 people between ages 14 and 49 in the United States has genital herpes.

However, U.S. rates of infection with HSV-1 and HSV-2 declined between 1999 and 2016, according to the U.S. Centers for Disease Control and Prevention (CDC). In 2016, among people between ages 14 and 49, the prevalence of HSV-2 was 12 percent, compared with 18 percent in 1999.

HSV-1 prevalence also declined during those years, from 59 percent in 1999 to 48 percent in 2016. (3,4)

Taking a look at the latest estimated global numbers, 67 percent of the people in the world who were younger than 50 had an infection caused by herpes simplex virus type 1 (HSV-1), according to the World Health Organization (WHO). That adds up to more than 3.7 billion people. And genital herpes caused by HSV-2 affects an estimated 491 million (13 percent) of people ages 15 to 49 worldwide. (5)

HSV-1 is mainly transmitted by oral-oral contact. It usually causes cold sores, also known as orolabial herpes, on or near the mouth.

HSV-1 is also an important cause of genital herpes. Around 140 million people between the ages of 15 and 49 years have a genital HSV-1 infection. Most live in the Americas, Europe, and the Western Pacific. (6)

Fewer people in wealthy, industrialized countries are developing HSV-1 infections as children, probably as a result of better hygiene and living conditions. In such countries, people are instead at risk of contracting a genital HSV-1 infection through oral sex.

In contrast, HSV-2 is almost always transmitted through vaginal or anal sex.

An infection with either HSV-1 or HSV-2 can lead to sores erupting in many places on and inside your body. These include your vulva, vagina, cervix, penis, scrotum, anus, inner thighs, buttocks, lips, mouth, and sometimes, though rarely, your eyes.

If you have genital herpes, it may be annoying, inconvenient, and painful at times. Still, it’s unlikely to cause you severe health problems. You will want to learn how to manage it and prevent its spread to other people.

The CDC does not recommend herpes testing for people who have no symptoms. They point out that diagnosing genital herpes in someone lacking any symptoms does not lead to them making changes in their sexual choices. They are no more likely to use condoms or to refrain from having sex than if they hadn’t been tested.

Also, false-positive test results can happen. A false positive is a test result saying you have herpes when actually you do not.

Even if you have no symptoms of herpes or of any other sexually transmitted disease, though, you should talk frankly with your doctor or another healthcare provider about your sexual activities to see if you should be screened for STDs, including herpes.

There are some situations where herpes blood tests can be useful, says the CDC:

• If you have genital symptoms that could be related to herpes
• If you now have, or have had, a sex partner with genital herpes
• If you want a complete STD exam, especially if you have multiple sex partners

Testing Options for HSV

Your doctor can order one of two kinds of HSV tests:

1. A test of some material taken from a lesion and then grown in a culture
2. A DNA test
3. An antibody blood test for HSV-1 and HSV-2

“The DNA test is generally more accurate. It picks up more infections than a culture,” says Handsfield.

DNA tests have become the more common HSV test in the United States, he adds, and suggests that you ask your doctor to order one if you’re being tested for herpes.

“If a test is done, also ask your doctor to request a determination of the virus type,” he says, to see if you have HSV-1 or HSV-2.

“The natural course of the disease and the need for treatment for HSV-1 and HSV-2 are different,” Handsfield says. With HSV-1, recurrent outbreaks are much less likely, and if they do occur are likely to be much more widely spaced.

“Forty percent of people with HSV-1 have no recurrent outbreaks in the year or two after infection, and often none after that,” says Handsfield.

In contrast, an infection with HSV-2 that produces symptoms often leads to outbreaks about four to five times each year. And a person with HSV-2 is more contagious during symptom-free periods. “So transmission via sex is far more likely with HSV-2 than with HSV-1,” he says.

“If you have HSV-2, you are more likely to benefit from ongoing antiviral therapy,” says Handsfield, considering how frequent outbreaks can be with that form of the virus.

Remember, though, while a herpes blood test can help determine if you have herpes infection, the test cannot tell you who gave you the infection.