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Herpes
simplex virus (HSV) infection produces recurring episodes of
small, painful, fluid-filled blisters on the skin or mucous
membranes. There are
two types of herpes simplex virus: HSV-1 and HSV-2:
A.
HSV-1 is the usual cause of Herpes Labialis (cold sores
on the lips) and Herpes Simplex Keratitis
(sores on the cornea of the eye - see Corneal
Disorders: Herpes Simplex Keratitis).
B.
HSV-2 causes Genital Herpes. This distinction is not
absolute: genital infections are sometimes caused by HSV-1. These
infections can be transmitted by direct contact with sores and
sometimes by contact with the oral and genital areas of
chronically infected people in between episodes of sores.
HSV infections
produce an eruption of tiny blisters on the skin or mucous
membranes. After the eruption of blisters subsides, the virus
remains in a dormant (latent) state inside the group of nerve
cells (ganglia) that supply the nerve fibers to the infected area.
Periodically, the virus reactivates, begins growing again, and
travels through the nerve fibers back to the skin—causing
eruptions of blisters in the same area of skin as the earlier
infection. Sometimes the virus may be present on the skin or
mucous membranes even when there is no obvious blister.
Reactivation of
latent oral or genital HSV infection may be triggered by a fever,
menstruation, emotional stress, or suppression of the immune
system. An episode of cold sores can develop following physical
trauma, such as a dental procedure or overexposure of the lips to
sunlight. Often the trigger is unknown.
Symptoms
and Complications
The first oral
infection with HSV usually causes sores inside the mouth (herpetic
gingivostomatitis). In addition, the person generally feels sick
and has fever, headache, and body aches. The mouth sores last 10
to 14 days and are often very severe, making eating and drinking
extremely uncomfortable. In some first oral infections, swollen
gums are the only symptom; occasionally, no symptoms develop.
Herpetic gingivostomatitis most commonly develops in children.
Recurrences of
oral HSV infection produce what are called "cold sores"
(so named because they are often triggered by colds). These sores
typically develop on the lips. An episode of cold sores begins
with tingling at the site, lasting from minutes to a few hours,
followed by redness and swelling. Usually, fluid-filled blisters
form and break open, leaving sores. The sores quickly form into a
scab. After a week, the scab falls off and the episode ends. Less
frequently, tingling and redness occur without blister formation.
Sometimes small clusters of herpes sores develop on the gums or
the roof of the mouth; these sores also last about a week and then
go away.
The first genital
HSV infection can be severe and prolonged, with multiple painful
blisters in the genital area. Fever and a general feeling of
illness (malaise) are common, and some people have burning during
urination. Occasionally, an infected person may have no symptoms.
A recurring attack of genital herpes begins with symptoms
(including local tingling, discomfort, itching, or aching in the
groin) that precede the blisters by several hours to 2 to 3 days.
Painful blisters surrounded by a reddish rim appear on the skin or
mucous membranes of the genitals. The blisters quickly break open,
leaving sores. Blisters also may appear on the thighs, buttocks,
or around the anus. In women, genital blisters may develop on the
vulva, in which case they are usually obvious and very painful.
Internal blisters may develop in the vagina or on the cervix; they
are less painful and are not visible. A typical episode of
recurring genital herpes lasts a week.
In people with a
weakened immune system, recurring outbreaks of genital or oral
herpes can result in progressive, gradually enlarging sores that
take weeks to heal. The infection may progress inside the body,
moving down into the esophagus and lungs. Ulcers in the esophagus
cause pain during swallowing, and infection of lungs produces
pneumonia with cough and shortness of breath.
Sometimes HSV-1 or
HSV-2 enters through a break in the skin of a finger, causing a
swollen, painful, red fingertip (herpetic whitlow).
HSV-1 sometimes
infects the cornea of the eye (herpes simplex keratitis (see Corneal
Disorders: Herpes Simplex Keratitis). This produces a painful
sore and blurred vision. Over time, the cornea can become cloudy,
causing a significant loss of vision and requiring corneal
transplantation.
Infants or adults
with a skin condition called atopic eczema can develop a
potentially fatal HSV infection in the area of skin that has the
eczema (eczema herpeticum (see Itching
and Noninfectious Rashes: Symptoms). Therefore, people with
atopic eczema should avoid being near anyone with an active herpes
infection.
Although it
usually infects only the skin and outer surfaces of the body, HSV
may rarely infect internal organs, such as the brain (herpes
encephalitis). Herpes encephalitis begins with confusion, fever,
and seizures and can be fatal.
Although an
infrequent event, a pregnant woman can transmit HSV infection to
her baby (neonatal herpes). Transmission usually occurs at birth,
when the baby comes into contact with infected secretions in the
birth canal. Infection of the baby is most likely when the woman
has visible herpes sores in the vaginal area, although many babies
become infected from mothers who have no apparent sores. Rarely,
HSV can be transmitted to the fetus during pregnancy. Newborns
with HSV infection become very ill. They may have widespread
disease, brain infection, or skin infection. Without treatment,
two thirds die, and even with treatment, many suffer brain damage.
Diagnosis
HSV infection is
usually easy for a doctor to recognize. If the doctor is unsure,
he may swab the sore and send the swab to the laboratory to grow
and identify the virus. Sometimes doctors examine material scraped
from the blisters under a microscope. Although the virus itself
cannot be seen, scrapings sometimes contain enlarged infected
cells (giant cells) that are characteristic of a viral infection.
Blood tests to identify antibodies to HSV and biopsy of the sores
can also be helpful. A new kind of blood test can distinguish
between HSV-1 infection and HSV-2 infection.
Treatment
No current
antiviral treatments can eradicate HSV infection, and treatment of
the first oral or genital infection does not prevent chronic
infection of nerves. However, treatment may relieve the discomfort
of a recurring outbreak slightly and shorten its duration by a day
or two. Treatment is most effective if started early, usually
within a few hours of the start of symptoms—preferably at the
first sign of tingling or discomfort, before blisters appear. In
people who have frequent, painful attacks, the number of outbreaks
can be reduced by continuous therapy (suppression) with antiviral
drugs.
A.
Penciclovircream can shorten the healing time and duration
of symptoms of a cold sore by about a day.
B.
Non-prescription
creams containing docosanol
(ABREVA)
or tetracaine
(CEPACOL
VIRACTIN)
may have a modest effect.
C.
Acyclovir
(ZOVIRAX),
valacyclovir
(VALTREX) or famciclovir
(taken by mouth for a few days may be the most effective
treatment.
D.
Severe HSV
infections are treated with intravenous acyclovir (ZOVIRAX).
People with herpes simplex keratitis are usually given trifluridine
(eye drops.
For people who
have minimal discomfort, the only treatment needed for recurring
herpes of the lips or genitals is to keep the infected area clean
by gentle washing with soap and water. Application of ice may be
soothing and reduce swelling.
Because herpes
simplex is contagious, people with infection of the lips should
avoid kissing during eruptions. People with genital herpes should
use condoms at all times. Even when there are no visible blisters,
the virus may be present on the genital surfaces and potentially
transmissible to sex partners.
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