Oral Herpes (Herpes Simplex)

Oral herpes is caused by the herpes simplex virus (HSV-1).

Oral herpes is a viral infection mainly of the mouth area and lips caused by a specific type of the herpes simplex virus. Oral herpes is also termed HSV-1, type 1 herpes simplex virus, or herpes labialis. The virus causes painful sores on the upper and lower lips, gums, tongue, roof of the mouth, inside the cheeks or nose, and sometimes on the face, chin, and neck. Infrequently, it may cause genital lesions. It also can cause symptoms such as swollen lymph nodes, fever, and muscle aches. People commonly refer to the infection as "cold sores."

Canker sores are sometimes thought to be caused by HSV, but this is not true. Canker sores occur only inside the mouth, on the tongue, and on the soft palate (roof of the mouth), not on skin surfaces. Although they reoccur, they are not contagious, usually are self-limiting, and have almost no complications. Canker sores are caused by substances that irritate the lining of the mouth.

What Is Herpes Simplex (HSV)? What Are the Stages of HSV-1 Infection?

There are two types of herpes simplex viruses (HSV), they are termed HSV-1 and HSV-2. These two viruses have distinctly different DNA, and both cause oral and genital lesions. However, HSV-1 causes about 80% of all oral lesions and only about 20% of genital lesions while HSV-2 causes the reverse (about 80% genital and 20% oral). Studies also suggest that in adolescents, up to 40% of genital herpes is caused by HSV-1 because of reported increased oral/genital contact (transmission by oral sex).

Oral herpes (HSV-1) infection (or exposure without noticeable infection) is common. About 65% of the U.S. population has detectable antibodies to HSV-1 by age 40. This article will focus on HSV-1, or oral herpes, not on HSV-2, also commonly known as genital herpes. Genital herpes is considered to be a sexually transmitted disease (STD). In addition, HSV-2 virus should not be confused with human papillomavirus (HPV), the cause of genital warts, and some cervical and other cancer types.

• HSV-1 affects only humans. Mouth sores most commonly occur in children 1-2 years of age, but they can affect people at any age and any time of the year. Oral inflammation from HSV-1 is also termed herpes gingivostomatitis.
• People contract HSV-1 by touching infected saliva, mucous membranes, or skin. Because the virus is highly contagious, a majority of the population is infected by at least one herpes subtype of HSV-1 before adulthood.
• After HSV-1 infects a person, it has a rather unique ability to proceed through three stages.
  • Stage 1 -- Primary infection: The virus enters the skin or mucous membrane, usually through small cracks or breaks, and then reproduces. During this stage, oral sores, blisters, and other symptoms, such as fever, may develop.
    • The virus may not cause any sores and symptoms. People may not know that they have an infection. This is called asymptomatic infection.
    • Asymptomatic infection occurs twice as often as the disease with symptoms.
  • Stage 2 -- Latency: From the infected site, the virus moves to a mass of nerve tissue in the spine called the dorsal root ganglion. There the virus reproduces again, usually without any symptoms, and becomes inactive, until reactivated by certain body conditions (see stage 3).
  • Stage 3 -- Recurrence: When people encounter certain stresses (also termed triggers), emotional or physical, the virus may reactivate and cause new sores and symptoms. The following factors may contribute to or trigger recurrence: stress, illness, ultraviolet light (UV rays including sunshine), fever, fatigue, hormonal changes (for example, menstruation), immune depression, and trauma to a site or a nerve region where previous HSV infection occurred.

Herpes simplex virus (HSV) is a DNA virus that causes sores in and around the mouth. Two herpes subtypes may cause these sores.

• Herpes simplex virus (type 1, herpes-1, or HSV-1) causes about 80% of cases of oral herpes infections. There is no evidence that HSV-1 viruses mutate into HSV-2 viruses.
• Another herpes simplex virus (type 2, herpes-2 or HSV-2) causes the other 20% and causes the majority of genital herpes infections.

These herpes viruses enter the body through small cuts, abrasions, or breaks in the skin or mucous membranes. The incubation period for herpes simplex infections is about three to six days. Transmission (spread) of the virus is person to person and more likely to occur if blisters or lesions are present. The majority enter after an uninfected person has direct contact with someone carrying the virus (either with or without noticeable lesions). Simply touching an infected person is often the way children get exposed. Adolescents and adults frequently get exposed by skin contact but may get their first exposure by kissing or sexual contact (oral and/or genital contact), especially for HSV-2. Statistical studies suggest that about 80%-90% of people in the U.S. have been exposed to HSV-1 and about 30% have been exposed to HSV-2. Usually, the contagious period continues until lesions heal. Some people (estimated from 30%-50%) occasionally shed herpes virus while having few or no associated symptoms or signs.

Oral lesions (and genital lesions) can reoccur. This happens because the HSV viruses are still alive but exist in nerve cells in a quiet, inactive (dormant) state. Occasionally, conditions in the body (see stage 3 above) allow the HSV to actively multiply, resulting in a new crop of lesions.

The HSV viruses multiply in the human cell by overtaking and utilizing most of the human cells functions. One of the HSV steps in multiplication is to take control of the human cell's nucleus and alter its structure. The altered nucleus (enlarged and lobulated or multinucleated) is what actually is used to help diagnose herpes simplex infections by microscopic examination. The reason sores appear is because as they mature the many HSV particles rupture the human cell's membrane as they break out of the cell.

Transmission of HSV-1 occurs by direct exposure to saliva or droplets formed in the breath of infected individuals. In addition, skin contact with the lesions on an infected individual can spread the disease to another individual. Although close personal contact is usually required for transmission of the virus, it is possible to transmit HSV-1 when people share toothbrushes, drinking glasses, or eating utensils.

Unfortunately, everyone is at risk to get HSV-1 infection. The majority of children between 6 months to 3 years of age are exposed to HSV-1 simply by contact with other humans. By 14-49 years of age, about 60% of the population has been infected, and by age 60, about 80%-85% of the population has been infected with HSV-1.

• Incubation period: For HSV-1, the amount of time between contact with the virus and the appearance of symptoms, the incubation period, is two to 12 days. Most people average about three to six days.
• Duration of illness: Signs and symptoms will last two to three weeks (healing time). Fever, tiredness, muscle aches, and irritability may occur.
  • Pain, sore lips, burning sensation, tingling, or itching occurs at the infection site before the sores appear. These are the early symptoms (prodrome). Sometimes these symptoms happen prior to the appearance of sores, bumps, pimple-like lesions, or blisters (herpes or herpetic stomatitis). Thereafter, clusters or groups of painful blisters (also termed fever blisters) or vesicles erupt or ooze with a clear to yellowish fluid that may develop into a yellowish crust. These blisters break down rapidly and appear as tiny, shallow gray ulcers on a red base. Fever blisters are smaller than canker sores. A few days later, they become crusted or scabbed and appear drier and more yellow.
  • Oral sores: The most intense pain caused by these sores occurs at the onset and can make eating and drinking difficult.
    • The sores can occur on the lips, gums, throat (causing a sore throat), the front of or under the tongue, the inside of the cheeks, and the roof of the mouth.
    • They can also extend down the chin and neck.
    • The gums can become mildly swollen, red-colored, and may bleed.
    • Neck lymph nodes often swell and become painful.
    • People in their teens and 20s can develop a painful throat with shallow ulcers and a grayish coating on the tonsils.

When to call the doctor

• Because cold sores are painful, people may have difficulty eating or drinking. To prevent dehydration, people should call their doctor if they cannot eat or drink adequately.
• If any of these symptoms, which suggest dehydration, occur, medical care should be obtained:
  • A decrease in urination (fewer wet diapers in infants)
  • Drowsiness
  • Irritability
  • Dry mouth
• Notify a doctor if there is uncertainty about what the oral sores are.
• If a child is younger than 6 weeks of age, notify a doctor if cold sores appear. Severe infection or disease complications occur more commonly in infants. For instance, besides affecting the mouth, HSV-1 may go to the brain and produce damage.
• People whose immune systems are weakened should also call their doctor if sores appear. If a person's immune system is weakened, they are more likely to have severe infection or disease complications. Pregnant women need to consult immediately if HSV infection is noticed, especially if they are close to term.

When to go to the hospital

Signs and symptoms of dehydration usually warrant going to a hospital's emergency department. Infants, especially under 6 weeks of age or if the infant appears to slow urine output or decrease fluid intake, should be evaluated by their pediatrician or in an emergency center if oral sores appear. Individuals with immune suppression (for example, patients undergoing chemotherapy, HIV patients, or cancer patients) should contact their doctors if they suspect a HSV-1 infection.

A doctor will base a presumptive diagnosis on information provided by the patient and on the physical examination. The characteristic appearance of the herpes sores leaves little doubt about the diagnosis, so the typical appearance of the sores is key to the diagnosis. This appearance helps distinguish oral herpes from oral thrush, shingles, gonorrhea, and syphilis. In addition, chapped or sunburned lips can resemble oral herpes, but the tissue stain (Tzanck smear, see below) shows no virus-induced cell changes. Further testing is usually not necessary but is sometimes done.

If a definitive diagnosis is needed, because, for example, the infection involves other organ systems, the doctor may conduct laboratory tests listed below:

• A sample (tissue or fluid) from the sores to identify the virus as HSV
• A viral culture analysis
• A staining test called the Tzanck smear (shows nonspecific cell nucleus changes due to HSV)
• Antigen and antibody studies (serologic and PCR tests to determine if infection is caused by HSV-1 or HSV-2)

• Use acetaminophen (Tylenol, Panadol) or anti-inflammatory drugs like ibuprofen (Excedrin, Advil, Motrin) for fever and muscle aches. There is data suggesting acetaminophen may be triggering asthma development in some children so parents should check with their child's pediatric doctor before using over-the-counter drugs containing acetaminophen.
• Drink plenty of fluids to prevent dehydration.
• Avoid physical contact with the lesions and any lesion secretions.

For mild infections, self-care may be adequate for treatment. Other treatments termed "home remedies" are not considered cures but can ease or hasten recovery. These remedies include aloe vera gel, cornstarch paste, and tea or mint leaves. A cool compress may reduce pain. There is no cure for the infection. People with severe infection symptoms, especially children, should be evaluated by a medical caregiver.

Treatment includes medication for fever (see above, anti-inflammatory drugs) and taking plenty of fluids.

• A topical anesthetic such as viscous lidocaine (Dilocaine, Nervocaine, Xylocaine, Zilactin-L) may be prescribed to relieve pain associated with oral blisters and lesions.
• Oral or IV medication does exist for HSV but is not recommended for people with a normal immune system. It is used only for people with weakened immune systems, infants younger than 6 weeks of age, or people with severe disease.
• Some people may require hospital admission.
  • Those with severe local infection
  • People whose infection has spread to other organ systems
  • People with weakened immune systems
  • Dehydrated individuals who need IV hydration
  • Infants younger than 6 weeks of age

Mild uncomplicated eruptions of herpes simplex require no treatment. Severe infection may require treatment with an antiviral agent. Oral antiviral drugs include

• acyclovir (Zovirax),
• valacyclovir (Valtrex),
• famciclovir (Famvir), and
• topical acyclovir or penciclovir (Denavir) creams may shorten attacks of recurrent HSV-1 if it is applied early, usually before lesions develop.

These drugs may stop viral replication in the skin but do not eliminate HSV from the body or prevent later outbreaks (HSV reactivation). These drugs are used more frequently with HSV-2 infections. Most investigators suggest consulting an infectious-disease expert when HSV-infected people need hospitalization. Research findings suggest laser treatments may speed healing and lengthen the time before any sores reappear.

Some patients will not require a physician to treat them. However, pediatricians, primary-care doctors, emergency-medicine doctors, dentists, dermatologists, and occasionally infectious-disease doctors treat HSV-1 infections.

Drink plenty of fluids.

• Use pain medications as instructed by the doctor.
• Use medications to control fever.
• Watch for signs and symptoms of dehydration.
• If any signs of dehydration develop, seek medical care immediately.

To reduce the chance of acquiring HSV-1, avoid touching saliva, skin, or mucous membranes of people who have HSV-1 lesions. Prevention of genital HSV may be accomplished by latex condoms, but protection is never 100%. Spermicides do not protect against HSV. Some clinicians recommend using dental dams (small latex squares) during oral sex, but like condoms, they are not 100% protective.

An experimental vaccine against HSV-1 is being tested in England that may be marketed in the near future. Currently, there is no cure for HSV-1.

The sores and symptoms of oral herpes usually completely disappear in two to three weeks with no scarring. However, the sores may reappear under certain stressful situations. Rarely, some complications develop in a few individuals:

• Atopic eczema
• Encephalitis
• Keratoconjunctivitis
• Pharyngitis
• Hepatitis
• Herpes whitlow (HSV blisters or lesions on the finger[s])