Herpes Simplex Health Article

Definition

Herpes is an infection caused by a herpes simplex virus 1 or 2, and it primarily affects the mouth or genital area.

Description

There are two strains of herpes simplex viruses. Herpes simplex virus type 1 (HSV-1) is usually associated with infections of the lips, mouth, and face. It is the most common herpes simplex virus among the general population and is usually acquired in childhood. Herpes simplex virus 2 (HSV-2) is sexually transmitted and is usually associated with genital ulcers or sores. Individuals may harbor HSV-1 and or HSV-2 and not have developed any symptoms.

Transmission

HSV-1 causes lesions inside the mouth that are often referred to as cold sores or fever blisters, and it is transmitted by contact with infected saliva. By adulthood, up to 90 percent of the population has antibodies to HSV-1. HSV-2 is sexually transmitted and not everyone develops symptoms when they have it. Up to 30 percent of adults in the United States have antibodies against HSV-2. Cross infection of type 1 and 2 viruses may occur from oral-genital contact. Herpes viruses can be transmitted to a newborn during vaginal delivery in mothers infected with herpes viruses, especially if the infection is primary (first occurrence) and is active at the time of delivery. The virus can lead to complications such as meningoencephalitis, which is an infection of the lining of the brain and the brain itself. It can also cause eye infections, in particular, of the conjunctiva and cornea.

Demographics

The prevalence of herpes simplex in the United States is as follows:

• Seventy to ninety percent of adults test seropositive (present in blood serum) for HSV-1.
• Up to 30 percent of adults test seropositive for HSV-2.
• The highest incidence of HSV-1 is in children six months to three years of age.
• The highest incidence of HSV-2 is in young adults between the age of 18 and 25 years.
• HSV-2 antibodies are present in approximately 20 percent of Caucasians and about 65 percent of African-American adults.

Causes and symptoms

A primary infection of HSV-1 typically occurs between six months and five years of age and is systemic (affecting the whole body). Transmission is generally via respiratory droplets (HSV-1) or direct contact (HSV-1 and HSV-2). The virus enters the body through mucosal surfaces, replicates in the cell nucleus, and then kills the host cell. The initial infection is self-limiting, but the immune system does not destroy the virus. The virus migrates along nerves to an area of regional ganglia (nerve centers) and then typically enters into a latent (sleeping) phase. Reactivation of the virus occurs in 50 percent of patients within five years, and it can be triggered by various factors:

• fatigue
• stress
• trauma
• immunocompromise (lack of normal immune response)
• illness, such as a cold
• fever
• sunburn
• menstruation
• sexual intercourse

The symptoms of a herpes infection can vary tremendously. Many infected individuals have few, if any, noticeable symptoms. Those who do have symptoms usually notice them from two to 20 days after being exposed to someone with HSV infection. Symptoms can last for several weeks, but the first episode of herpes is usually worse than subsequent outbreaks. The predominant symptom of herpes is the outbreak of painful, itching blisters filled with fluid on and around the external sexual organs or, for oral herpes, on or very near the lip. Females may have a vaginal discharge and experience flu-like symptoms with HSV2 outbreaks, including fever, headache, muscle aches, and fatigue. There may be painful urination, and swollen and tender lymph glands in the groin. More often than not the blisters disappear without treatment in two to 10 days, but the virus remains in the body, lying dormant among clusters of nerve cells until another outbreak is triggered.

Many people are able to anticipate an outbreak when they notice a warning sign (a tingling sensation, called a prodrome) of the approaching illness. It is when they feel signs that an outbreak is about to start that they are particularly contagious, even though the skin still appears normal. Most people with genital herpes have five to eight outbreaks per year, but not everyone has recurrent symptoms. In time, the number of outbreaks usually decreases. Oral herpes can recur as often as monthly or only one or two times each year. Sores typically come back near the site of the first infection, but there are fewer sores with recurrences that heal faster and are less painful.