What is the difference between HSV1 & HSV2? Oral and Genital Herpes

Last Updated on September 7, 2021 by Valinda Riggins Nwadike, MD, MPH

In telling a new partner about a genital herpes infection, it’s common to compare cold sores – an oral herpes infection – with a genital one. However, is that really a good comparison? The emotional and social attitudes surrounding the two infections are wildly different, and those perceptions alone can make an objective comparison and subsequent discussion quite difficult.

Is there a worse infection? Is HSV1 (commonly cold sores) and HSV2 (commonly genital herpes), virtually, the same thing? By comparing the infections, we can help answer those questions while also beginning to understand why there is a polarizing difference in the way society views oral herpes vs. genital herpes.

Scientifically Speaking

Under a microscope, the HSV1 and HSV2 viruses look nearly identical. They share approximately 50% of their DNA and 85% of their genetic material. While the percentage of DNA they share is relatively low when considering humans share over 98% of their DNA with chimps, how the DNA behaves and forms into genes is more important, because they share the major segments of DNA that are needed to contribute to biological functions – the genetic material.

That means HSV1 & HSV2 behave similarly, but from an evolutionary stand-point, they sort of diverged years ago when humans started having sex face to face. That’s why a lot of their DNA is different, despite their genetic make-up remaining strikingly similar. What’s important to understand from this is that the genes the types share have a big impact on the viruses’ appearance and behavior, and in both the HSV1 and the HSV2 types, the genetic material looks and behaves similarly.

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How are HSV1 & HSV2 the same?

Both the herpes simplex type 1 and the herpes simplex type 2 viruses infect the body’s mucous membranes (usually the mouth or genitals, but there are also mucous membranes located in the nose, eyes, and ears). Once infected, they establish latency (lie dormant) in the nervous system.

When the viruses become reactivated due to physical or emotional stimuli, they replicate and then travel the nerve pathways to the surface of the skin – sometimes that results in a physical outbreak, other times, it results in viral shedding. That is why both types can recur and then be transmitted to others even when there are no noticeable symptoms present.

Clinically, HSV1 & HSV2 present identically, meaning, you can’t differentiate between one type of the virus or the other by the severity of the initial outbreak or how the lesions look alone. The physical symptoms of HSV1 & HSV2 are indistinguishable.

For both HSV1 & HSV2, it is thought that at least two-thirds of infected people experience no symptoms at all or symptoms that are too mild to notice. As a result, it’s estimated that as many as the same amount (two-thirds) of people are entirely unaware they are infected.

How are HSV1 and HSV2 different?

The primary difference between HSV1 & HSV2 is where the virus typically establishes latency in the body. HSV1 usually remains dormant in the nerve cells near the base of the neck, and from there, viral shedding and outbreaks tend to occur on the mouth or face. HSV2, on the other hand, usually establishes latency in the nerve cells near the base of the spine, and from there, it recurs in the genital area.

However, that difference is not absolute, and either type can reside in either parts of the body while infecting oral or genital areas. Unfortunately, most people aren’t aware that HSV1 and HSV2 can reside in both locations (more than 30% of new genital herpes infections are the result of HSV1), and that is one of the primary contributors to the recent rise in genital HSV1 infections: the misconception that the types are fundamentally different.

“People don’t understand that you can have type 1 genitally or orally and that the two types are essentially the same virus,” says Marshall Clover, manager of the National Herpes Hotline. “One type is associated with stigma, the other is “just a cold sore” – our society has a euphemism for it so we don’t even have to acknowledge that it’s herpes.”

HSV1 Might be More Risky

Because of the euphemisms we’ve attached to HSV1, people assume that oral herpes is a mild infection, occasionally bothersome, but never dangerous. For most, that assumption is accurate. When it infects the lips, face, or genitals, HSV1 is often quite mild and more of a nuisance than anything else.

However, for some, HSV1 occurs in the eye, causing ocular herpes, and ocular herpes is a potentially serious infection that can lead to blindness. In rarer cases, HSV1 spreads to the brain, causing herpes encephalitis, and herpes encephalitis is a dangerous infection that can lead to death.

The range and potential severity of HSV1 infections has led some experts to view the type as more risky than usually perceived. “This is here say, but I think type 1 is a more significant infection than type 2,” says Spotswood Spruance, MD, an oral HSV specialist at the University of Utah. “Type 1, and the morbidity associated with it, is underestimated.”

HSV2 Still Poses Some Risks Too

Herpes simplex type 2 is the most frequent cause of neonatal herpes, a very uncommon, but dangerous infection in newborns.

HSV2, however, unlike HSV1, rarely causes other complications or spreads to different areas of the body outside of its original vicinity. Under most circumstances, it is not a major health threat.

Should I compare colds sores to genital herpes?

So, is the comparison accurate?

Since the primary difference between HSV1 and HSV2 lies in where the type establishes itself in the nervous system, comparing the two infections can help partners understand an HSV infection while also alleviating some misconceptions.

There are some obvious differences between the two viruses when comparing location of infection, risk, and social perceptions, but the viruses themselves look and behave similarly, so an initial comparison can be quite helpful.

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