Herpes Simplex

 

    by Marissa Martinez

 

Disease and General Characteristics:

Herpes Simplex is a viral infection caused by the Herpes Simplex Virus (HSV) (1). There are two types of Herpes Simplex Virus, Herpes Simplex Virus 1 (HSV-1) often referred to as fever blisters and/or cold sores and Herpes Simplex Virus 2 (HSV-2) most commonly known as genital herpes (1).The etiologic agent for the Herpes Simplex Virus is Herpesviridae (2); the Herpes Simplex Virus is a double stranded DNA enveloped virus with a doughnut shaped capsomere (3).

 

Historical Information:

            The origin of herpes in human history is unknown but the Herpes Simplex was first documented by ancient Greeks as sores that seem to “creep” over the surfaces of skin. Vidal, 1873, first demonstrated the Herpes Simplex Virus to be infections caused by human inoculation (8). There is also evident speculation around two thousand years ago the Roman Emperor Tiberius attempted to curb an epidemic of herpes from the mouth by outlawing kissing during public ceremonies and rituals (8).

 

Reservoirs and Means of Transmission:

Humans and animals serve as reservoirs for herpes simplex but only humans demonstrate signs of the disease (3). The transmission of herpes simplex is through direct contact (4) and most easily passed on through genital to genital and/or oral to genital contact (5). The majority of Type 1 transmission is through kissing, sharing eating utensils, or by sharing towels (1) while Type 2 transmission is through sexual contact with an infected person (3). The herpes simplex virus is very contagious to where it can be contracted from people who have a chronic HSV infection even when they are between episodes of exposure (4).

 

Virulence Mechanisms:

             Like all viruses, the herpes simplex virus binds to a cells surface through protein receptors located on the cell membrane (3). The Herpes simplex virus genome encodes 11 surface glycoproteins which include gC; gC can bind to the complement C3 protein and deplete it from the host’s serum thus inhibiting complement-mediated reactions creating an immune escape (3). Also gE and gI proteins can bind with the Fc portion of IgG which can coat the virus and therefore be hidden from the immune system (3). With genital (HSV-2) herpes the virus enters the body through a break in the skin during vaginal, oral, or anal sex (7). The virus then travels through your body and inhabits nerve cells near the spinal cord (7) where they remain in a latency stage until triggered by factor; the virus then travels back down towards the nerve axon and the recurrence of the infection with its symptoms occurs at the same site of the initial infection (3). Herpes simplex viruses are capable of cell to cell transmission in the presence of humoral antibodies due to syncytia (mass of cytoplasm that is not separated into individual cells) formation between infected cells (3). 

 

Signs and Symptoms:

         Many people who are infected with the herpes simplex virus do not have any symptoms, if they do show symptoms they are varied for each person (7). The most common first signs and symptoms of herpes simplex is a tingling, stinging, or burning sensation on the skin (1) followed by an outbreak of fluid filled blisters which appear on skin and mucous membranes (4), the site of the initial infection. For oral herpes, blisters formed on the lips can also transmit to the tongue with an increase in saliva with the possibility of foul breath. With genital herpes, sores can be found on the vagina, cervix, penis, and around the genital areas such as the buttocks, thighs, and anus (1). Initial outbreaks of genital herpes can cause flu-like symptoms such as fever. Women can have more severe symptoms from Type 2 outbreaks such as nerve pain, lower abdominal pain and urinary difficulties (12). Some people may also demonstrate pre outbreak or prodrome symptoms such as muscle aches, headache, flu-like malaise and swollen lymph glands (12). Herpes outbreaks occur in two stages: primary and recurrent (1).During the primary infection the blisters can break and eventually cause the fluid from the blisters to ooze out and crust (1) leaving sores which can last anywhere from 2 to 4 weeks to heal for the first exposure (6). As long as the virus (fluid in the blisters) is kept moist it can remain infectious (3). In the recurrent phase the outbreaks are far less severe than the initial primary infection and are initiated by various factors such as stress, excessive sunlight exposure, and fever (1).  

 

Control and Treatment:

         There is no cure for the herpes simplex virus (7) but it can be treated with oral anti-viral medications such as acyclovir, famciclovir, or valacyclovir (1). These antiviral medications assist in treating outbreaks and if used constantly can suppress outbreaks (1). The best way to prevent the spreading of herpes is to avoid contact of the infected area from other people. For HSV-1 avoid kissing, sharing lip balms, and drinking cups(1); for HSV-2 abstain from sexual contact with others but if you choose to have sexual relations always be sure to use a condom as the virus is not capable of crossing the condom barrier (7).

 

Key tests for Identification:

            Usually the appearance of herpes simplex is often typical and no testing is required to confirm. If diagnosis of herpes simplex is uncertain a swab from the infected skin for culture is taken to the laboratory (1). Blood tests can also be used to detect the presence of herpes simplex antibodies. Though effective this test can not be used to confirm an active case of herpes or whether you can pass it to others (11). 

           

Global and Local Cases:

            The Herpes Simplex virus affects millions of people worldwide annually. For people from the ages of 15 to 49 years old, an estimated 536 million were living with HSV-2 in 2003 and of that 23.6 million were newly infected (10). In 2006, 371,000 people in the United States had genital herpes (HSV-2) compared to initial reports in 1966 of only 19,000 (9). The majority of genital herpes cases in the United States are caused by HSV-1, contracted through oral sex, (1) and more women were infected than men (10). Age is also a factor in contracting herpes as the number of people infected increased with age (10). A large portion of the population has HSV-1; about 50 to 80 percent of American adults have oral herpes (5). In underdeveloped countries with poor hygiene, HSV-1 antibodies are found in more than 90% of children (3).

             

References:

 

1.      American Academy of Dermatology. “Herpes Simplex.” 2008. URL: http://www.aad.org/public/publications/pamphlets/viral_herpes_simplex.html accessed on 12/2/08.

 

2.      “The Big Picture Book of Viruses: Herpesvirdidae.” 2007. URL: www.virology.net/Big_Virology/BVDNAherpes.html accessed on 12/2/08.

 

3.      Dr. Richard Hunt. “Herpes Viruses.” November 6, 2008. URL:    http://pathmicro.med.sc.edu/virol/herpes.htm    accessed on 12/2/08.

 

4.      Dr. Marguerite Urban. “Herpes Simplex Virus Infections.” February 2007. URL:      www.merck.com/mmhe/sec17/ch198/ch198e.html accessed on 12/5/08.

 

5.      American Social Health Association, Inc. “Learn about Herpes >Fast Facts.” 2007. URL: www.ashastd.org/herpes/herpes_learn.cfm accessed on 12/5/08.

 

6.      Centers for Disease Control & Prevention. “Genital Herpes”. February 6, 2008. URL: www.cdc.gov/std/Herpes/default.htm accessed on 12/8/08.

 

7.      The American College of Obstetricians and Gynecologists. “Genital Herpes Patient Education Pamphlet.” January 2008. URL: www.acog.org/publications/patient_education/bp054.cfm accessed on 12/6/08

 

8.      Herpes-Coldsores.com. “What is Herpes? And other basics…” 2008. URL: www.herpes-coldsores.com/herpes_information.htm accessed on 12/8/08.

 

9.      Division of STD Prevention. “Table 42. Selected STDs and complications…” November 13, 2007. URL: www.cdc.gov/std/stats/tables/Table42.htm accessed on 12/3/08.

 

10.  Looker, Katherine J et al. “An estimate of the global prevalence and incidence of herpes simplex virus type 2 infection.” October 2008. URL: www.who.int/bulletin/volumes/86/10/07-046128-ab/en/ accessed on 12/3/08.

 

11.  Texas Department of State Health Services. “Herpes.” July 29, 2008. URL: www.dshs.state.tx.us/hivstd/info/herpes/default.shtm accessed on 12/3/08.

  

12.  University of Maryland Medical Center. “Herpes simplex.” October 1, 2006. URL: www.umm.edu/patiented/articles/what_symptoms_of_herpes_simplex_virus_000052_2.htm accessed on 12/5/08.