Herpes simplex overview

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Classification Orofacial Infection Anogenital Infection Ocular Infection Herpes Encephalitis Neonatal Herpes Herpetic Whitlow Herpes Gladiatorum Mollaret's Meningitis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Lakshmi Gopalakrishnan, M.B.B.S.

Overview

Herpes simplex is a viral disease caused by Herpes simplex viruses. Infection of the genitals is commonly known as herpes and predominantly occurs following sexual transmission of the type 2 strain of the virus (HSV-2). Oral herpes, colloquially called cold sores, is usually caused by the type 1 strain of herpes simplex virus (HSV-1). Both viruses cause periods of active disease—presenting as painful blisters containing infectious virus particles—that lasts 2-21 days and is followed by remission when the sores disappear. Most cases of genital herpes are asymptomatic, although viral shedding may still occur. HSV-1 and HSV-2 are transmitted by direct contact with a sore or body fluid of an infected individual. After initial infection, these viruses move to sensory nerves, where they reside as life-long, latent viruses. The viruses lie dormant in trigeminal ganglia that provide sensation to the lips, lower mouth and neck, or in lumbrosacral that supply sensation to the genitals, perineum and upper legs. Occasionally, these viruses reactivate and return to the area of skin infected during the primary infection. Triggers for recurrences are uncertain but may include sunburn, ultraviolet light, wind, trauma, surgery, and stress. Over time, episodes of active disease reduce and the frequency of recurrences is regulated by specific immunity developed against the virus.

Classification

Anogenital Infection

HSV-2 is widespread, affecting an estimated 1 in 4 females and 1 in 5 males in the United States. Most young, sexually active patients who have genital, anal, or perianal ulcers have either genital herpes or syphilis. The frequency of each condition differs by geographic area and population; however, genital herpes is the most prevalent of these diseases.

Ocular Infection

Ocular herpes is generally caused by HSV-1 and is a special case of facial herpes infection known as herpes keratitis. It begins with infection of epithelial cells on the surface of the eye and retrograde infection of nerves serving the cornea.

Herpes Encephalitis

Herpes simplex encephalitis (HSE) is a very serious disorder and one of the most severe viral infections of the human central nervous system.

Herpes Simplex Neonatorum

Neonatal HSV disease is a rare but serious condition, usually as a consequence of vertical transmission of the virus from the mother to the newborn child, although an estimated 10% of cases may be acquired postnatally from a parent, caretaker, or sibling. From 1/3,000 to 1/20,000 of live births are infected with neonatal herpes. Approximately 22% of pregnant women have had a previous exposure HSV-2, and a further 2% or more women acquire the virus during pregnancy. Particularly among young adults, genital herpes infections are increasing caused by HSV-1.

Herpetic Whitlow

A herpetic whitlow is a lesion on a finger or thumb caused by the herpes simplex virus. In children the primary source of infection is the orofacial area, and it is commonly inferred that the virus (in this case commonly HSV-1) is transferred by the chewing or sucking of fingers or thumbs. In adults it is more common for the primary source to be the genital region, with a corresponding preponderance of HSV-2. It is also seen in adult health care workers such as dentists because increased exposure to the herpes virus.

Herpes Gladiotorum

Individuals that participate in contact sports such as wrestling, rugby, and soccer sometimes acquire a condition caused by HSV-1 known as herpes gladiatorum, scrumpox, wrestler’s herpes or mat herpes. Abraded skin caused by contacts sports provides an area of entry for HSV-1. Symptoms present within 2 weeks of direct skin-to-skin contact with an infected person, and include skin ulceration on the face, ears, and neck. This disorder may cause fever, headache, sore throat and swollen glands, and occasionally affects the eyes. Physical symptoms sometimes recur in the skin.

Mollaret's Meningitis

Mollaret's meningitis is a recurrent inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. Mollaret's meningitis is caused by herpes simplex virus. It is a recurrent, benign, aseptic meningitis.

Pathophysiology

HSV-1 and HSV-2 can be found in and released from the sores that the viruses cause, but they also may be released between outbreaks from the skin that does not appear to have a sore. Generally, a person can only get HSV-2 infection during sexual contact with someone who has a genital HSV-2 infection. Transmission can occur from an infected partner who does not have a visible sore and may not know that he or she is infected. HSV-1 can cause genital herpes, but it more commonly causes infections of the mouth and lips, so-called fever blisters. HSV-1 infection of the genitals can be caused by oral-genital or genital-genital contact with a person who has HSV-1 infection. Genital HSV-1 outbreaks recur less regularly than genital HSV-2 outbreaks.

The surest way to avoid transmission of genital herpes, is to abstain from sexual contact, or to be in a long-term mutually monogamous relationship with a partner who has been tested and is known to be uninfected. Genital ulcer diseases can occur in both male and female genital areas that are covered or protected by a latex condom, as well as in areas that are not covered. Correct and consistent use of latex condoms can reduce the risk of genital herpes. Persons with herpes should abstain from sexual activity with uninfected partners when lesions or other symptoms of herpes are present. It is important to know that even if a person is asymptomatic, he or she can still infect sex partners. A positive HSV-2 blood test most likely indicates a genital herpes infection.

Epidemiology and Demographics

Prevalence of HSV-1 and HSV-2 infections varies throughout the world. Socioeconomic status appears to be an important factor associated with HSV-1 infection levels with developing countries, such as those in Sub-Saharan Africa, showing higher levels of HSV-1 and younger acquisition rates than industrialized countries like the United States and countries in Northern Europe. The risk of infection for HSV-1 is associated with lower income and a more crowded living environment. Levels of HSV-2 infections are much lower in the U.S. (20-30%), Australia (12%), the United Kingdom (4%) and Germany (14%). Risk Factors for acquiring HSV-2 include: Female sex; black race; commencement of sexual activity at a younger age; higher number of sexual partners; and lower socioeconomic status.

Asymptomatic Shedding

HSV asymptomatic shedding occurs at some time in most individuals infected with herpes.

Recurrence

Genital herpes can cause recurrent painful genital sores in many adults, and herpes infection can be severe in patients with suppressed immune systems. It is important that women avoid contracting herpes during pregnancy because a newly acquired infection during late pregnancy poses an increased risk of transmission to the baby. If a woman has active genital herpes at delivery, a cesarean delivery is usually indicated. Patients infected with herpes are more susceptible to HIV infection; hence, herpes may indirectly play a role in the spread of HIV.

Clinical Presentation

Disorders such as herpetic whitlow, herpes gladiatorum, and ocular herpes are caused by herpes simplex viruses. Infection of the central nervous system causes serious disorders - these include herpes encephalitis, Mollaret's meningitis, and possibly Bell's palsy. In newborn babies, infection by herpes viruses (neonatal herpes) can be highly serious, resulting in brain damage or even death. In immunocompetent people, herpes simplex is not typically life-threatening. However, individuals with compromised immune systems can develop serious HSV infections such as encephalitis.

Diagnosis

The clinical diagnosis of genital herpes is both nonsensitive and nonspecific. The classical painful multiple vesicular or ulcerative lesions are absent in many infected persons. HSV-1 is causing an increasing proportion of first episodes of anogenital herpes in some populations (such as young women and MSM) and might now account for most of genital herpes infections. Recurrences and subclinical shedding are less frequent for genital HSV-1 infection than for genital HSV-2 infection. A patient’s prognosis and the type of counseling needed depends on the type of genital herpes (HSV-1 or HSV-2) causing the infection; therefore, the clinical diagnosis of genital herpes should be confirmed by laboratory testing. Both virologic and type-specific serologic tests for HSV should be performed to diagnose patients with or at risk for STDs.

Treatment

Treatments are available to reduce the symptoms and speed up the healing process of herpes infections but there is currently no cure. Antiviral medications can shorten and prevent outbreaks during the period of time the person takes the medication. In addition, daily suppressive therapy for symptomatic herpes can reduce transmission to partners. Antiviral drugs, such as aciclovir and valaciclovir, taken orally, reduce viral reproduction and shedding, and some topical creams, such as Docosanol and Tromantadine prevent the virus from entering the skin. Some other drugs reduce herpetic symptoms by synergising with oral antiviral medication; Cimetidine and probenecid can reduce aciclovir clearance and aspirin can reduce inflammation associated with viral infection. Some natural remedies may have potential benefits in reducing herpes outbreaks or their symptoms. No vaccine is currently available to prevent or treat herpes.