Virus / "Bad" Virus
The Truth about HSV-1 and HSV-2
alike are HSV-1 and HSV-2? In this feature, we look at the latest scientific
facts about the two types of herpes simplex virus, as well as social attitudes
toward oral and genital herpes.
When many people first tell someone they have genital herpes, they start by
comparing the infection to oral herpes, or cold sores. How apt is the
comparison? In spite of scientific facts, the social stigma and emotional
attitudes surrounding genital herpes can make it hard to compare it objectively
with an oral infection that most people casually accept. Following the unspoken
assumptions of our society, many people still believe there is a
"good" herpes virus (HSV- 1, the usual cause of cold sores) and a
"bad" herpes virus (HSV-2, the usual cause of genital herpes).
In this feature, we take a look at HSV- 1 and 2 to see how alike and different
the two viral types really are. We asked leading researchers how the two compare
in terms of severity, recurrences, and transmission rates. We asked how often
each occurs outside its usual site of preference, and how each behaves in the
genital area. We questioned how much immunity having one type orally or
genitally provides against getting the second type.
In addition, we looked at the way our society views oral and genital herpes.
What's behind the very different images the two types carry? And what can we do
about it? In an interview, counselors at the National Herpes Hotline suggest
ways to help replace judgmental social assumptions with a healthy attitude.
Under a microscope, HSV- 1 and 2 are virtually identical, sharing approximately
50% of their DNA. Both types infect the body's mucosal surfaces, usually the
mouth or genitals, and then establish latency in the nervous system. For both
types, at least two-thirds of infected people have no symptoms, or symptoms too
mild to notice. However, both types can recur and spread even when no symptoms
The primary difference between the two viral types is in where they typically
establish latency in the body- their "site of preference." HSV-1
usually establishes latency in the trigeminal ganglion, a collection of nerve
cells near the ear. From there, it tends to recur on the lower lip or face.
HSV-2 usually sets up residence in the sacral ganglion at the base of the spine.
From there, it recurs in the genital area.
Even this difference is not absolute either type can reside in either or both
parts of the body and infect oral and/or genital areas. Unfortunately, many
people aren't aware of this, which contributes both to the spread of type 1 and
to the misperception that the two types are fundamentally different.
"People don't understand that you can have type 1 genitally or orally, 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."
The common myth is that HSV-1 causes a mild infection that is occasionally
bothersome, but never dangerous. The reality? HSV-1 is usually mild, especially
when it infects the lips, face, or genitals. However, in some cases type 1 can
recur spontaneously in the eye, causing ocular herpes, a potentially serious
infection which can lead to blindness. In very rare cases HSV- 1 can spread
spontaneously to the brain, causing herpes encephalitis, a dangerous infection
that can lead to death. HSV-1 is also the usual cause of herpes whitlow, an
infection on the finger, and "wrestler's herpes," (herpes gladiatorum)
a herpes infection on the chest or face.
The range and potential severity of HSV-1 infections lead some experts to view
the virus as more risky than usually perceived. "This is heresy, 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."
By comparison, HSV-2 is widely believed to be a painful, dangerous infection
that affects only people with very active sex lives. The reality? Some 22% of
adult Americans from all backgrounds, income levels, and ethnic groups have
HSV-2. Like HSV-1, type 2 is usually mild-so mild that two- thirds of infected
people don't even know they have it. Type 2 rarely causes complications or
spreads to other parts of the body. It is the most common cause of neonatal
herpes, a rare but dangerous infection in newborns; however, type 1 causes up to
one-third of neonatal infections.
The two types do behave somewhat differently depending on whether they are
residing in their site of preference-the mouth and face for HSV-1, and the
genital area for HSV-2. But both types are quite common, and under most
circumstances neither is a major health threat. That's one reason medical
professionals tend to dismiss HSV -2 despite the emotional trauma a diagnosis
can cause for a patient.
While HSV can be a frustrating and painful condition for some people, in general
the virus is less a medical problem than a social problem. For most of us,
genital herpes is no more dangerous than a cold sore.
how much of a physical problem HSV poses for a person depends largely on three
factors. The first is how well the person's immune system is able to control the
Differences in immune response may be the main reason that some people are
bothered by frequent cold sores or genital herpes outbreaks while others are
not. It's also the reason that both HSV-1 and 2 can pose serious challenges for
infants, who have a limited immune response; and for people with compromised
immune systems, including people with cancer, AIDS, severe burns, and people
taking immunosuppressant medications.
The second factor affecting outbreaks is how long a person has had the
infection. Over time, recurrences of both HSV- 1 and 2 tend to decrease, for
reasons that aren't entirely clear.
In the case of oral HSV-1, many of the approximately 100 million Americans who
are infected acquired the virus when they were children. By the time they're
adults, only some 5% of people are bothered enough to consider oral HSV-1 a
medical problem, according to Spruance.
On the other hand, almost all of the approximately 40 million Americans infected
with HSV-2 acquired the virus as teenagers or adults. In the first year, those
who have recurring outbreaks experience an average of four to six episodes. Over
time, as with oral infections, the number of outbreaks usually drops off.
A third factor influencing the frequency of HSV -1 and 2 outbreaks is whether
the virus is established in its site of preference. While HSV can infect both
genital and oral areas, both types cause milder infections when they are away
from "home" territory. Outside their site of preference, both type 1
and 2 lose most of their punch.
For example, most people infected with HSV-1 in the genital area have few, if
any, outbreaks after the initial episode, far fewer than is typical with either
oral HSV-1 or genital HSV-2. While experts estimate that some 30% of genital
herpes infections in the United States may be caused by HSV-1, only 2- 5% of
recurring genital outbreaks are caused by HSV-1. Research conducted by Lawrence
Corey, MD, and colleagues at the University of Washington in Seattle shows that
genital HSV-2 recurs 10 times more often than genital HSV-1.
According to a study by Wald et al. (New England Journal of Medicine, 1995),
among 110 women with genital herpes, the average number of recurrences per year
for those with genital HSV-1 was zero. Other studies have shown an average of
about one outbreak per year (Benedetti, Annals of Internal Medicine, 1994).
Similarly, HSV-2 infection in the oral area-outside its site of preference-very
rarely causes problems. First of all, oral, HSV-2 infections are rare, for
reasons discussed below. But even when an infection occurs, recurrent outbreaks
are uncommon. In one study (Lafferty et al., New England Journal of Medicine,
1987), oral HSV-2 recurred an average of 0.01 times a year in newly infected
people. "I've never convincingly seen an oral type 2 recurrence," says
A possible fourth factor affecting recurrence rate is viral type. According to
the Lafferty study, genital HSV-2 infections were the most frequently recurring
herpes infections, followed by oral HSV-1, genital HSV-1, and last of all, oral
a number of readers have attested over the years, many people with genital
herpes are at least as concerned about transmission-the likelihood of spreading
the virus to a partner-as about their own health. On the other hand, few people
with oral herpes share this concern. Is this because one type is more contagious
than the other?
The short answer is no. Both viral types are easily transmitted to their site of
preference, and can also be spread to other sites. Both are most contagious
during active outbreaks, but are often spread through viral shedding when there
are no recognizable symptoms. According to Spruance, people with recurrent oral
HSV-1 shed virus in their saliva about 5% of the time even when they show no
symptoms. In the first year of infection, people with genital HSV-2 shed virus
from the genital area about 6-10% of days when they show no symptoms, and less
often over time. (Both of these figures reflect shedding as detected by viral
From here, however, the question of transmissibility gets more complicated.
Acquisition of one type is more difficult-though certainly possible-if you
already have the other type. This is because either type, contracted orally or
genitally, causes the body to produce antibodies, some of which are active
against both HSV-1 and 2. This acquired immune response gives some limited
protection if the body encounters a second type. When a person with a prior HSV
infection does contract the second type, the first episode tends to be less
severe than when no prior antibodies are present.
On a practical level, this means oral HSV-1 is often the most easily acquired
herpes infection. Usually the first herpes simplex virus that people encounter,
oral HSV-1, is typically spread simply by the kind of social kiss that a
relative gives a child. Because children have no prior infection with any HSV
type, they have no immune defense against the virus.
By the time they're teenagers or young adults, about 50% of Americans have HSV-1
antibodies in their blood. By the time they are over age 50, some 80-90% of
Americans have HSV-1 antibodies.
By comparison, almost all HSV-2 is encountered after childhood, when people
become sexually active. Those who have a prior infection with HSV-1 have an
acquired immune response that lowers - though certainly doesn't eliminate-the
risk of acquiring HSV-2. According to one study (Mertz, Annals of Internal
Medicine, 1992), previous oral HSV-1 infection reduces the acquisition of
subsequent HSV-2 infection by 40%.
A prior infection with oral HSV-1 lowers the risk of acquiring genital HSV-1
even further. Studies show that genital HSV-1 infections almost always occur in
people who have no prior infection with HSV of either type (Corey, Annals of
Internal Medicine, 1983).
In the absence of prior oral infection, however, HSV-1 spreads easily to the
genital area, usually through oral sex. In some countries, such as Japan and
parts of Great Britain, genital HSV-1 is as common as genital HSV- 2, or more
"Prevalence rates of genital HSV-1 differ based on the practice of oral sex
and on the percentage of people who are HSV-1 positive from childhood,"
explains Anna Wald, MD researcher at the University of Washington at Seattle.
Finally, the question of immunity and HSV types is complicated by an additional
issue. Some studies suggest that the ganglia themselves may acquire some
immunity to HSV after they are exposed to one viral type.
In the laboratory, infection of ganglia with more than one virus is difficult,
suggesting that it may be more difficult to acquire a second HSV type in a
location where you already have HSV. A prior genital infection with HSV-1, for
example, may give more protection against genital HSV-2 than a prior oral
infection with HSV-1.
What does all this mean on a practical level? Let's look at some examples to
find out. Say you have genital HSV-1 and your partner has genital HSV-2. If you
have unprotected sex, there is a small but real risk that you will get HSV-2,
resulting in more outbreaks and more shedding. "We have documented cases
where a person acquires HSV-2 after a prior genital HSV- 1 infection," says
Wald. "I don't think it happens often, but it does happen."
On the other hand, it's very unlikely that your partner will get genital HSV- 1
from you. "I've never seen a case of a person acquiring HSV-1 on top of
HSV-2," says Wald. "It's possible, but it would be unusual."
What if your partner has genital HSV-2 and you perform oral sex on him or her?
Will you get HSV- 2 in the mouth? Given the widespread practice of oral sex
(some three-quarters of all adults practice it, according to The Social
Organization of Sexuality, 1994) and the prevalence of genital HSV-2 infection,
you might expect oral HSV-2 to be relatively common. It's not.
According to one study, almost 100% of recognizable HSV-2 infection is genital (Nahmias,
Scandinavian Journal of Infectious Diseases Supplement, 1990). One reason is
that most adults are already infected with HSV-1 orally, which provides some
immunity against infection with HSV 2. Another reason is that oral HSV-2 rarely
reactivates, so even if an infection does exist, no one knows.
So far we've been talking about transmission of HSV-1 or 2 from its site of
preference. What about transmission from another site? Say you acquire genital
HSV-1 through oral sex. Can you spread the virus to a partner through genital
The answer is yes, but probably not as easily as it was spread through oral sex.
The main reason is that the virus reactivates and sheds less often outside its
site of preference. Only about one quarter of people with genital HSV- 1 shed
virus at all in the absence of symptoms, while 55% of people with HSV-2 do (Wald,
New England Journal of Medicine, 1995). "Shedding data appear to parallel
recurrence data, meaning that people who have a lot of recurrences also have a
lot of shedding," says Wald.
While HSV- 1 can be spread from genitals to genitals, "we think it is
spread more easily through oral sex because HSV-1 reactivates more frequently in
the oral area," says Wald. However, she warns, "transmission of
genital HSV-1 during asymptomatic shedding has been documented." In other
words, genital HSV-1 can be spread through genital sex, even when there are no
If HSV infection is as easily transmitted from the mouth as from the genitals,
then why do people take steps to prevent genital but not oral infection? Why
don't we kiss through dental dams?
ironic, isn't it?" says Wald. "It's not about health, it's about
can tell us all day that the main difference between the two viral types is
simply their site of preference-whether they typically occur above the waist or
below. But the unspoken attitudes of our society send a different message.
That's just the problem, social attitudes whisper. Below the waist is bad.
"People think of oral herpes as the "good" herpes and genital
herpes as the "bad" kind," says Glover of the National Herpes
Hotline. "It's partly that they don't understand the similarities between
HSV-1 and 2. But it's also that good and bad is how our culture views sex and
The inescapable fact is that HSV-1 is usually spread through contact with
infected lips, while HSV-2 usually spread through contact with infected
genitals. From a social point of view, the problem is not the disease; it's how
you got it.
Whether we like it or not, the social prejudice against genital herpes, no
matter which virus causes it, is a reality. "People have more trouble
explaining to a new partner that they have genital herpes, even if it's HSV- 1,
than if they have a cold sore," says Glover. "Just saying the word
'genital' is like an anvil that pulls the sentence down".
Is this topic making you crazy? For people who have trouble dealing with social
attitudes toward genital herpes, the blatant double standard society applies to
oral herpes can be frustrating, to say the least.
"Talk to a wise friend," suggests Rebecca, a health communication
specialist on the National Herpes Hotline. "Join a support group. Find
someone you respect and exchange ideas them. It's always reassuring to see that
not everyone lives inside the walls our society builds around sexual issues and
It's also worth hoping that new research on the similarities between HSV-1 and
2, as well as increased public education about genital herpes, can help lower
the level of misunderstanding about both types of the virus. Today, the
greatest difference between HSV- 1 and 2 appears to be the way we think about
them. Tomorrow, that may change....