Last Updated on June 4, 2020 by Valinda Riggins Nwadike, MD, MPH
Acquired Immune Response
This is where herpes transmission risk gets a little more complicated.
There are 9 types of the human herpes virus: HHV1 and HHV2 are the types known as herpes simplex viruses (HSV type 1 and HSV type 2); HHV3 is know as varicella-zoster, the type that causes chickenpox and shingles, or herpes zoster; HHV4 is the epstein-barr virus (EBV), causing mononucleosis, or mono; HHV5 is know as cytomegalovirus (CMV), and it can also cause mono; HHV6a, HHV6b, and HHV7 are all associated with roseola, and HHV8 occurs in patients who are diagnosed with AIDS. For the purpose of this article, we will focus on HSV, two of the 9 human herpes virus types.
If you already have one type of HSV, you’re less likely to contract an additional type or the same type in a new location. It is certainly possible, and people do contract more than one type of the herpes simplex virus, or the same type in two separate locations, but the likelihood decreases when someone already has one type.
That is because when someone contracts herpes, HSV1 or HSV2, their body begins to produce antibodies. Some of those antibodies are active against both types of the virus. Those active antibodies are called an acquired immune response, and they provide some protection against new infections, so when the body encounters a second type of HSV or the same type in a new location, they are less likely to contract/spread it.
Should someone contract a second type of HSV infection, despite their acquired immune response, they are also less likely to have a severe first episode, or their first episode will be less severe than had they not previously had an HSV infection.
Prior Oral HSV1 Infection – Cold Sores
Having an acquired immune response that lowers the risk of additional infection is most common with HSV1. Since so many folks have been exposed to oral HSV1, or cold sores, the antibodies established in their system can reduce their subsequent risk of infection with HSV2 by as much as 40%.
What’s more, a prior oral HSV1 infection lowers the risk of acquiring HSV1 genitally even further. Studies show that genital HSV1 infections almost always occur in people who have not had an HSV infection of either type.
When there have been no prior infections from HSV1 orally, HSV1 spreads easily to the genitals via oral sex. In some countries (Japan & Great Britain, for example) genital HSV1 is just as or even more common than genital HSV2. As a result, genital HSV1 prevalence rates are directly related to how a population is practicing oral sex and how many of them, on average, contract oral herpes or HSV1 during childhood.
Can we develop immunity to HSV?
So, if the presence of one type makes it harder to acquire another, then can we develop immunity?
Some studies have found that the ganglia – the nerve endings where the virus lies dormant – may acquire some immunity after having been exposed to one viral type. In a controlled setting, researchers had trouble infecting the ganglia with more than one virus type, which suggests that it may be difficult to acquire a second type of HSV in the same location.
For example, a prior genital infection of HSV1 might give you even more protection against a genital HSV2 infection than a prior oral infection with HSV1.
This can all get a little bit confusing, I know. Let’s see if I can break it down for you.
In order of risk – most likely to contract HSV to least likely:
- One partner has HSV (either type), the other partner does not
- One partner has HSV1, the other partner has HSV2 – transmitting a different type to a new location
- One partner has genital HSV1, the other partner has genital HSV2 – transmitting a different type to the same location
Can you spread HSV to another part of your body?
Yes, that is called self-inoculation.
However, HSV is not as easily spread to another part of the body as it was initially contracted because your antibodies will provide some protection. The risk of self-inoculation is even further reduced if the first HSV infection is outside of the types’s site of preference (HSV1 orally and HSV2 genitally), because the virus reactivates and asymptomatically sheds less when it is outside of its site of preference.
Although there’s no way to discern who will asymptomatically shed the virus and when it will be shedding, shedding data appear to parallel recurrence data, meaning that people who have a lot of recurrences also have a lot of shedding.
Why is there a big social discrepancy between oral and genital HSV?
Considering what we know about herpes transmission risk, it’s somewhat surprising people still have incredibly differing opinions about oral herpes vs. genital herpes.
People actually take precautions to reduce their risk of genital herpes, but when it comes to cold sores, or a genital infection caused by HSV1, people tend to be miles apart.
The fact of the matter is, the misunderstandings lie not in the infections themselves but in people’s perception of how the infection is acquired. Socially, it’s acceptable to contract an infection from touching infected lips, but it’s not acceptable if the infection came from touching infected genitals.
New research further emphasizing the similarities between the two types of infections will definitely help bridge the gaps, and in time, additional education will reduce the social discrepancies between HSV1 & HSV2 transmission.
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Did this post help clarify your herpes transmission risk questions? Have you always wondered what your likelihood of spreading herpes was as well? Share your thoughts in the comments section below!