Herpes labialis is also known as orolabial herpes, herpes facialis, herpes simplex, simplex virus, herpes catarrhalis, herpes febrilis, and cold sores.
Herpes labialis is an infection of the mouth and lips by herpes simplex virus (HSV-1). It is characterized by painful sores on lips, gums, tongue, roof of the mouth, and inside the cheeks and sometimes on the face and neck. It may also cause symptoms such as fever and muscle aches. The sores heal within 2-3 weeks. HSV-1 affects only humans. Primary infection most commonly occurs in children 1-2 years of age, but they can affect people at any age and any time of the year.
There are two types of HSV, 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 (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.
People contract HSV-1 by touching infected saliva, mucous membranes, or skin. Because the virus is highly contagious, a majority of the population are 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 and other symptoms, such as fever, may develop.
The virus may not cause any sores and symptoms. You may not know that you have it. 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.
Stage 3 – Recurrence: When people encounter certain stresses, emotional or physical, the virus may reactivate and cause new sores and symptoms. Investigators have suggested the following factors may contribute to recurrence: stress, ultraviolet light (including sunshine), fever, fatigue, hormonal changes (for example, menstruation), immune supression and trauma to a site or a nerve region where previous HSV infection occurred.
Etiology
Herpes labialis infection occurs when the herpes simplex virus comes into contact with oral mucosal tissue or abraded skin of the mouth. Infection by the type 1 strain of herpes simplex virus (HSV-1) is most common; however, cases of oral infection by the type 2 strain are increasing because of the changing sexual behaviour.
Cold sores are the result of the virus’s reactivating in the body. Once HSV-1 has entered the body, it never leaves. The virus moves from the mouth to quietly reside (“remain latent”) in the central nervous system. In approximately one-third of people, the virus can “wake up” or reactivate to cause disease. When reactivation occurs, the virus travels down the nerves to the skin where it may cause blisters (cold sores) around the lips, in the mouth or, in about 10% of cases, on the nose, chin, or cheeks. Cold sore outbreaks may be influenced by stress, menstruation, sunlight, sunburn, fever, or local skin trauma. Surgical procedures such as dental or neural surgery, lip tattooing, or dermabrasion are also common triggers. HSV-1 can in rare cases be transmitted to newborn babies by family members or hospital staffs who have cold sores; this can cause a severe disease called Neonatal herpes simplex.
People can transfer the virus from their cold sores to other areas of the body, such as the eye, skin, or fingers; this is called “autoinoculation.” Eye infection, in the form of conjunctivitis or keratitis, can happen when the eyes are rubbed after touching the lesion. Finger infection (herpetic whitlow) can occur when a child with cold sores or primary HSV-1 infection sucks his or her fingers.
Prevention
Avoiding touching an active outbreak site, washing hands frequently while the outbreak is occurring, not sharing items that come in contact with the mouth, and not coming into contact with others by avoiding kissing, oral sex, contact sports can reduce the likelihood of the infection being spread to others.
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