Herpes Simplex 2 Virus
Herpes Simplex 2 Virus
Disease History, Characteristics, and Transmission
Introduction
Genital herpes (often known just as herpes) is an infection by the Herpes Simplex virus (HSV) which leads to the formation of painful sores in the genital area. Most cases of genital herpes are caused by HSV-2, but the closely related HSV-1, which normally causes cold sores, is occasionally involved. Both HSVs belong to the herpes family of viruses, all of which exist as viral particles of a diameter around 200 nm (nanometers). Other significant herpes viruses include the Varicella-Zoster virus, which causes chicken pox, Epstein-Barr virus, and Cytomegalovirus (CMV). The herpes virus invades cells and may lie dormant for many years, causing no obvious symptoms. However, a herpes infection can be activated at any time and often recur throughout life. Symptoms typically are present only when the herpes virus is active. Although the virus itself cannot be eliminated, symptoms of active infection, like genital sores, can be treated with antiviral drugs.
Disease History, Characteristics, and Transmission
HSV-2 frequently causes no symptoms when it enters the body, creating a latent infection within nerve cells. However, HSV-2 infection can be activated—or re-activated— by triggers such as stress, sunlight exposure, fever, broken skin, and menstruation. New virus particles then move towards the genital area where they start to multiply in surface cells, causing them to swell and release fluid. This leads to the formation of groups of small, painful blisters, which may eventually rupture to give an ulcer or sore. Men develop genital sores on the tip or shaft of the penis and in the rectal area. Women develop the sores in the vulva, perineum, cervix, vagina, and rectal area. The symptoms are often more severe among women. The first episode of genital herpes may be accompanied, in around 10% of cases, by symptoms such as fever, malaise, aches and pains, and a swollen groin. Meningitis, an illness involving inflammation of the membranes covering the brain and spinal cord, is an occasional complication of genital herpes. The symptoms typically lessen or disappear within four to five days. Sores usually heal within two weeks. Women infected with HSV-2 may transmit herpes to their babies during childbirth. Neonatal herpes (herpes infections in newborns) varies in its severity, but has an overall mortality rate as high as 60% and can cause long-term neurological complications. As many as 1% of child birthing women in the United States shed HSV-2 during delivery, and 6% of the babies thus exposed develop neonatal herpes. HSV-1 is much less likely to lead to neonatal herpes.
In 80% of cases, genital herpes recurs. However, symptoms are most often less severe during recurrence. Prodromal symptoms (early signs that herald an illness), such as a tingling sensation in the genital area, often precede a recurrence of genital herpes.
HSV-2 infection is transmitted through sexual contact with an infected person and is one of the most common of the sexually transmitted diseases. An infected, asymptomatic person (a person who has no symptoms) can still infect sexual partners. The time between sexual contact and the appearance of symptoms, if any, is about five days.
Scope and Distribution
HSV-2 infection is found around the world and is the most common cause of genital ulcers. However, detection of HSV-2 antibody, a sign of infection, is unusual before puberty. Around one third of sexually active adults in the Western world have HSV-2 antibody. It has been isolated from the cervix or urethra of between 5–12% of adults attending sexual health clinics. Mostly these patients are asymptomatic or have tiny, unnoticed genital lesions.
In the United States, it is estimated that there are around half a million new cases of HSV-2 per year. Women are more at risk of contracting HSV-2 infection than men. Risk increases for both men and women who have multiple sexual partners. A heterosexual woman with one partner has a 10% chance of contracting the infection. A heterosexual man in the same situation has a negligible risk. Homosexual men run a higher risk of developing HSV-2.
HSV-2 infection also makes transmission of the human immunodeficiency virus (HIV) more likely.
WORDS TO KNOW
ASYMPTOMATIC: A state in which an individual does not exhibit or experience symptoms of a disease.
DORMANT: Inactive, but still alive. A resting non-active state.
LATENT INFECTION: An infection already established in the body but not yet causing symptoms, or having ceased to cause symptoms after an active period, is a latent infection.
LESIONS: The tissue disruption or the loss of function caused by a particular disease process.
PRODROMAL SYMPTOMS: Prodromal symptoms are the earliest symptoms of a disease.
Treatment and Prevention
There is no cure or vaccine for HSV-2 infection. There are a number of antiviral drugs that can be used to treat outbreaks of genital herpes, such as acyclovir, valacylcovir, and famciclovir. Those who know they are infected, because of past outbreaks, can help protect their sexual partners by using condoms. People with active genital sores should not have sexual contact with others even if using a condom, since sores and lesions can appear outside of the area covered by the condom.
The Division of Sexually Transmitted Disease (STD) at Centers for Disease Control and Prevention (CDC) recommends that “all pregnant women should be asked whether they have a history of genital herpes. At the onset of labor, all women should be questioned carefully about symptoms of genital herpes, including prodromal symptoms, and all women should be examined carefully for herpetic lesions.”
Impacts and Issues
HSV-2 usually lies dormant within the body, with people being unaware that they can infect others through sexual contact. As herpes infections can be life threatening in the newborn and in those with impaired immunity, the risk of infection is a serious concern. HSV-2 infection has also been found to promote HIV transmission. The link between genital ulcers and HIV has been known for over 20 years, but more sensitive methods of detecting HSV-2 infection has allowed detailed investigation of the connection. Genital ulceration, even if it is not visible, attracts the CD4 cells that HIV infects. More recent research, from India, has shown that HIV infection is twice as likely among people with newly acquired HSV-2 infection, as compared to those with long-standing infections. Activation of HSV-2 infection in those who also have HIV may also make them even more likely to transmit HIV to an uninfected partner. These findings suggest a new approach to reducing HIV infection. Treatment with acyclovir, a relatively cheap drug, could help prevent reactivation of HSV-2 thereby potentially reducing the risk of HIV transmission.
According to the Centers for Disease Control (CDC) from the 1970s to the early 1990s, the prevalence of herpes cases in the United States increased by 30%. The most dramatic rise in new cases occurred among teens and young adults. Since the late 1990s, the incidence of herpes infections in young people has stabilized. Many credit aggressive education campaigns about safer sex practices for this change. Medical testing and care, honest discussion between sexual partners about health issues, and the habitual and proper use of condoms can help reduce—but not eliminate—the risk of transmitting HSV-2.
IN CONTEXT: REAL-WORLD RISKS
Centers for Disease Control and Prevention, Sexually Transmitted Diseases Treatment Guidelines 2006 states that the following recommendations apply to counseling of persons with HSV infection:
- Persons who have genital herpes should be educated concerning the natural history of the disease, with emphasis on the potential for recurrent episodes, asymptomatic viral shedding, and the attendant risks of sexual transmission.
- Persons experiencing a first episode of genital herpes should be advised that suppressive therapy is available and is effective in preventing symptomatic recurrent episodes and that episodic therapy sometimes is useful in shortening the duration of recurrent episodes.
- All persons with genital HSV infection should be encouraged to inform their current sex partners that they have genital herpes and to inform future partners before initiating a sexual relationship.
- Sexual transmission of HSV can occur during asymptomatic periods. Asymptomatic viral shedding is more frequent in genital HSV-2 infection than genital HSV-1 infection and is most frequent during the first 12 months after acquiring HSV-2.
- All persons with genital herpes should remain abstinent from sexual activity with uninfected partners when lesions or prodromal symptoms are present.
- The risk of HSV-2 sexual transmission can be decreased by the daily use of valacyclovir by the infected person.
- Recent studies indicate that latex condoms, when used consistently and correctly, might reduce the risk for genital herpes transmission.
- Sex partners of infected persons should be advised that they might be infected even if they have no symptoms. Type-specific serologic testing of asymptomatic partners of persons with genital herpes is recommended to determine whether risk for HSV acquisition exists.
- The risk for neonatal HSV infection should be explained to all persons, including men. Pregnant women and women of childbearing age who have genital herpes should inform their providers who care for them during pregnancy and those who will care for their newborn infant. Pregnant women who are not infected with HSV-2 should be advised to avoid intercourse during the third trimester with men who have genital herpes. Similarly, pregnant women who are not infected with HSV-1 should be counseled to avoid genital exposure to HSV-1 during the third trimester (e.g., oral sex with a partner with oral herpes and vaginal intercourse with a partner with genital HSV-1 infection).
- Asymptomatic persons diagnosed with HSV-2 infection by type-specific serologic testing should receive the same counseling messages as persons with symptomatic infection. In addition, such persons should be taught about the clinical manifestations of genital herpes.
SOURCE: Centers for Disease Control and Prevention, Sexually Transmitted Diseases Treatment Guidelines 2006
IN CONTEXT: REAL-WORLD FACTS
Centers for Disease Control and Prevention, Sexually Transmitted Diseases Treatment Guidelines 2006 state that “genital herpes is a chronic, life-long viral infection. Two types of HSV have been identified, HSV-1 and HSV-2. The majority of cases of recurrent genital herpes are caused by HSV-2, although HSV-1 might become more common as a cause of first episode genital herpes. At least 50 million persons in the United States have genital HSV infection. The majority of persons infected with HSV-2 have not been diagnosed with genital herpes. Many such persons have mild or unrecognized infections but shed virus intermittently in the genital tract.”
“The majority of genital herpes infections are transmitted by persons unaware that they have the infection or who are asymptomatic (without observable symptoms) when transmission occurs.”
SOURCE: Centers for Disease Control and Prevention, Sexually Transmitted Diseases Treatment Guidelines 2006
See AlsoChickenpox (Varicella); Herpes Simplex 1 Virus; Shingles (Herpes Zoster) Infection.
BIBLIOGRAPHY
Books
Gates, Robert H. Infectious Disease Secrets. 2nd ed. Philadelphia: Hanley and Beltus, 2003.
Gillespie, S., and K. Bamford Medical Microbiology and Infection at a Glance. Malden: Blackwell, 2000.
Wilson, Walter R., and Merle A. Sande Current Diagnosis & Treatment in Infectious Diseases. New York: McGraw Hill, 2001.
Periodicals
Wald, A., and L. Corey. “How Does Herpes Simplex Virus Type 2 Influence Human Immunodeficiency Virus Infection and Pathogenesis?” The Journal of Infectious Diseases. 187 (2003): 1519–1512.
Web Sites
Skin Care Guide Network. “Herpes Guide—from Cold Sores to Genital Herpes.” February 21, 2007 <http://www.herpesguide.ca> (accessed February 22, 2007).
Susan Aldridge