It should not be confused with conditions caused by other viruses in the herpesviridae family such as herpes zoster, which is caused by varicella zoster virus. The differential diagnosis includes hand, foot and mouth disease due to similar lesions on the skin. Lymphangioma circumscriptum and dermatitis herpetiformis may also have a similar appearance.
The herpes simplex virus is probably the most well-known virus of the herpes family, and it is just as contagious. Herpes simplex infects epithelial cells and remains latent in neurons. HSV-1 causes recurrent oropharyngeal lesions, commonly known as “fever blisters" or "cold sores.” It is also the primary cause of sporadic encephalitis (inflammation of the brain), gingivostomatitis (inflammation of the gums and mucous lining of the mouth), and keratoconjunctivitis (severe dryness of the eye that involves the cornea) and dendritic corneal ulcers (also called HSV keratitis) in which the cornea becomes affected by herpetic lesions that look like the dendrites of neurons in the brain.

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.
Although the cause is unknown, outbreaks are often associated with periods of weakened immune systems, skin wounds, menstruation, fever, nerve damage, tissue damage from surgery, or exposure to extreme climate situations. A genital herpes outbreak or episode occurs when the HSV-1 or HSV-2 virus is reactivated from its dormant stage. Genital herpes is an incurable disease, and once you contract it, you may experience outbreaks throughout your lifetime. Those who are experiencing their first herpes episode of genital herpes can expect to have several (typically four or five) outbreaks within a year. Over time these recurrences usually decrease in frequency and severity. The first outbreak of herpes is often the longest outbreak experienced. After that, short and inconsistent episodes can be managed and treated with antiviral medication.
A 2004 study in the New England Journal of Medicine found that suppressive therapy decreases the risk of HSV-2 transmission from symptomatic, infected partners to uninfected partners by 48%. So “the risk of transmission is significantly reduced, but cannot be eliminated even with suppressive therapy,” Johnston explains, and she stresses that the virus can be passed along even without signs or symptoms.
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