Herpes viruses

background

Herpes is a group of viruses that infect humans. Types of herpes viruses include herpes simplex virus types 1 and 2 (HSV-1 and HSV-2, respectively), human herpesvirus type 3 (HHV-3, or the varicella-zoster virus), human herpesvirus type 4 (HHV-4, including Epstein-Barr virus and lymphocryptovirus), human herpesvirus type 5 (HHV-5, or cytomegalovirus), human herpesvirus type 6 (HHV-6, including human B-cell lymphotrophic virus and roseolovirus), human herpesvirus type 7 (HHV-7), and human herpesvirus type 8 (HHV-8, including rhadinovirus and Kaposi's sarcoma-associated virus).
The viruses fall into three categories: alpha-herpes viruses (HSV-1, HSV-2, and varicella-zoster virus), beta-herpes viruses (cytomegalovirus, HHV-6, and HHV-7), and gamma-herpes viruses (Epstein-Barr virus, lymphocryptovirus, and HHV-8). The viruses are different and cause various conditions with many unique signs and symptoms. However, all herpes viruses share some common properties, including a pattern of active symptoms followed by latent (inactive) periods with no symptoms that can last for months, years, or even for a lifetime. Herpes symptoms may even never reappear. The severity of herpes symptoms depends on the type of virus with which the individual is infected.
Herpes simplex virus type 1 (HSV-1) is also known as a cold sore or fever blister. Herpes simplex virus type 2 (HSV-2) is also known as genital herpes. Human herpesvirus type 3 is also referred to as varicella-zoster virus or VZV. Herpes varicella is the primary infection that causes chicken pox, and herpes zoster is the reactivation of the varicella virus that causes shingles.
Herpes simplex type 1 and type 2 infections are generally marked by painful, watery blisters in the skin or mucous membranes (such as the mouth or lips) or on the genitals. Lesions heal with a crust-forming scab, the hallmark of herpes. This is particularly likely during an outbreak, although individuals may shed virus between outbreaks. Although no cure is yet available, antiviral treatments exist that reduce the likelihood of viral shedding. An HSV infection on the lips, commonly known as a "cold sore" or "fever blister," should not to be confused with a canker sore; canker sores (painful sores on the tongue or oral membranes in the mouth) are not caused by HSV.
Herpes is a contagious infection that spreads when the carrier is producing and releasing (or "shedding") the virus. Herpes viruses are transmitted from human to human in different ways. With HSV-1, contact and infection can occur directly from another human (such as mouth-to-mouth or hand-to-mouth contact) or through the use of everyday objects that have come in contact with the virus, including razors, towels, dishes, and glasses. Genital herpes, or HSV-2, can only be contracted through direct sexual contact with an infected partner (genital-to-genital, mouth-to-genital, or hand-to-genital contact, not through kissing). Occasionally, oral-genital contact can spread oral herpes to the genitals (and vice versa). Individuals with active herpes lesions on or around their mouths or their genitals should avoid oral sex. The varicella-zoster (chicken pox) virus spreads through the humidity in the air when inhaled and mainly spreads during the incubation period, which is just before an outbreak of symptoms.
After an initial or primary infection, herpes viruses establish a period called latency, during which the virus is present in the cell bodies of nerves that innervate (attach) to the area of the original viral outbreak (such as the genitals, mouth, and lips). At some point, this latency ends, and the virus becomes active again. While active, the virus begins to multiply (this is called shedding) and becomes transmittable again. This shedding may or may not be accompanied by symptoms. During reactivation, virus is produced in nerve cells and transported outwardly via the nerve to the skin. The ability of herpes viruses to become latent and reactive explains the chronic (long-term), recurring (returning) nature of a herpes infection.
Recurrence of the viral symptoms is usually milder than the original infection. Recurrence may be triggered by menstruation, sun exposure, fever-related illness, stress, immune system imbalances, and other unknown causes.

Related Terms

Acquired immunodeficiency syndrome, AIDS, antiviral, B-cell lymphotrophic virus, Bell's palsy, CFS, chicken pox, chickenpox, chronic fatigue syndrome, CMV syndrome, cold sore, colitis, contagious, corticosteroid, cutaneous, cytomegalovirus, down syndrome, EBV, encephalitis, epidural, Epstein-Barr virus, exanthema subitum, fetal alcohol syndrome, fever blister, fibromyalgia, genital herpes, gingivostomatitis, glomerulonephritis, Guillain-Barré syndrome, hepatitis, herpes labialis, herpes zoster ophthalmicus, herpetic, HHV-1, HHV-2, HHV-3, HHV-4, HHV-5, HHV-6, HHV-7, HHV-8, HIV, Hodgkin's disease, HSV anterior uveitis, HSV blepharitis, HSV conjunctivitis, HSV infectious epithelial keratitis, HSV keratitis, HSV neonatal infection, HSV retinitis, human herpesvirus type 4, human herpesvirus type 5, human herpesvirus type 6, human herpesvirus type 7, human herpesvirus type 8, human immunodeficiency virus, immunocompromised, immunofluorescence, Kaposi's sarcoma, Kaposi's sarcoma-associated virus, KS, latency, lesion, lymphocryptovirus, lymphocytes, lymphoma, lymphoproliferative disorders, lyphotrophic virus, MCD, meningitis, mono, monocytes, mononucleosis, multicentric Castleman's disease, myocarditis, neuropathy, ocular lesions, oropharyngeal, PCR, PEL, PHN, pneumonia, polymerase chain reaction, postherpetic neuralgia, primary effusion lymphoma, prodromal, pyrexia, Ramsay Hunt syndrome, retinitis, rhadinovirus, roseola, roseola infantum, roseolovirus, sexually transmitted disease, shedding, shingles, STD, steroid, topical, uveitis, vaccine, varicella-zoster virus, vesicle, VZV.

type of herpes

Herpes simplex virus (HSV-1 and HSV-2) :
Herpes simplex virus (HSV): There are two types of HSV, including herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2). Although some symptoms of HSV-1 and HSV-2 are similar (such as lesions), they are usually transmitted differently and involve different areas of the body.
Herpes simplex virus type 1 (HSV-1): Herpes simplex virus type 1 is the cause of herpes labialis (fever blisters, cold sores) and involves the lips and inflammation of the gums and mouth. Other conditions caused by HSV-1 include oropharyngeal, cutaneous, and ocular lesions, including HSV blepharitis, HSV conjunctivitis, HSV keratitis, HSV infectious epithelial keratitis, HSV anterior uveitis, HSV retinitis, and HSV neonatal infection.
HSV-1 is a very common virus, affecting more than 50% of the adult population in the United States by the age of 20. However, it is thought that up to 90% of adults have been exposed to the virus during their lifetime. After the first episode, the virus lies dormant in the nerves or skin around the original area until something sets the virus off into another eruption. Colds, flu, and even stress can cause an outbreak of cold sores. It is not well understood why an individual has an outbreak at one time of life and not another. Most people contract oral herpes when they are children by receiving a kiss from a friend or relative.
The first symptoms usually appear within one, two, or as late as three weeks after contact with an infected person. The lesions of herpes labialis usually last for 7-10 days, then begin to resolve. Typically, the first episode of HSV-1 infections involves the formation of a single blister or cluster of blisters; during this first episode, the symptoms are usually the most pronounced. Following the active infection, the virus becomes latent (dormant), residing in the nerve cells, and may reactivate later, causing a new outbreak at or near the original site. Approximately 25% of people infected by HSV-1 experience recurrent episodes or outbreaks.
It should be noted that HSV-1 is becoming a major cause of genital herpes as well, due to unprotected sex. In some studies, it is now a more important cause of genital herpes than HSV-2.
Herpes simplex virus type 2 (HSV-2): HSV-2 is considered the primary cause of genital herpes. According to the Centers for Disease Control and Prevention (CDC), in the United States, at least 45 million people aged 12 years and older have had herpes simplex virus type 2 (HSV-2, or genital herpes) infection. According to researchers at the CDC, HSV-2 is present in as many as one in six people aged 14-49 years in the United States.
HSV-2 is a sexually transmitted disease (STD), meaning that an individual must engage in sexual activity (oral or manual sex or intercourse) in order to transmit or be infected with this virus. In men and women aged 14-49 years, HSV-2 infection is more common in women (approximately one out of five women) than in men (almost one out of nine). This may be because male-to-female transmissions are more likely than female-to-male transmission. Anyone who is sexually active may contract genital herpes. There are no documented cases of a person getting genital herpes from an inanimate object such as a toilet seat, bathtub, or towel. Herpes is a very fragile virus and does not live long on surfaces outside the body. Signs and symptoms that occur during the first outbreak, which usually takes place within two weeks of virus transmission, can be quite severe. Lesion formation is the most common HSV-2 symptom; these lesions are commonly blisterlike but may also resemble a red spot, a pimple, an ingrown hair, razor burn, hemorrhoids, or an insect bite. The sores associated with HSV-2 infections typically heal within 2-4 weeks. In addition to the first outbreak of sores, other signs and symptoms that often occur during the primary episode may include a second crop of sores and flulike symptoms such as fever and swollen glands.
However, an estimated 90% of individuals infected with HSV-2 are not aware of their infection. Many people infected with HSV-2 may never have sores, or they may have very mild sores that go unrecognized or are mistaken for insect bites, abrasions, yeast infections, "jock itch," or other skin conditions. In fact, approximately one-third of individuals with active lesions in their genital area are still unaware that they are showing this symptom.
Most people diagnosed with a first episode of genital herpes can expect to have 4-5 outbreaks (called symptomatic recurrences) within a year. Symptoms of these outbreaks can include warning symptoms, or "prodromes," that include itching, tingling, or painful feelings at the site of the outbreak approximately two days before the recurrent lesion forms. Often these outbreaks decrease in frequency over time, although the virus is still present in the body. There is no cure for this recurrent (returning) infection, which may cause embarrassment and emotional distress. Having genital herpes does not preclude an individual from having a normal relationship. If the individual or partner is infected with HSV-2, steps can be taken to manage the transmission of the virus (see Precautions).
With HSV-2 (genital herpes), transmission of the virus can occur when the infected sexual partner does not have an active outbreak. Although some individuals may not know they are infected with HSV-2 or do not show symptoms of the infection, they can still transmit the virus to others.
Although HSV-2 is widely recognized as a cause of genital herpes, it can cause oral herpes as well. Moreover, HSV-1 can cause genital herpes, resulting in similar symptoms as infections caused by HSV-2.
With genital infections, HSV-2 is more likely to shed than HSV-1, especially in women. It is possible that over half of the people infected with HSV-2 shed the virus at some time without having any symptoms or rash. It is also estimated that one-third of all HSV-2 infections are caused when a noninfected person comes in contact with someone who is shedding virus without symptoms.
HSV-2 can be passed in the urine or genital discharge of an infected person. The viruses become reactivated secondary to certain stimuli, including fever, physical, or emotional stress, ultraviolet light exposure (sunlight or tanning beds), and nerve injury.
Human herpesvirus type 3 (varicella-zoster, or HHV-3) :
Human herpesvirus type 3 (varicella-zoster):Both shingles and chicken pox are caused by human herpesvirus type 3 (HHV-3), or the varicella-zoster virus. HHV-3 is still referred as either herpes varicella (the primary infection that causes chicken pox) or herpes zoster (the reactivation of the virus that causes shingles). Humans are the only known carriers of HHV-3.
Chicken pox: Chicken pox is usually a childhood disease. Over 90% of cases occur in children aged 14 years and younger. Before widespread vaccination, the incidence of chicken pox in the United States approached the annual birth rate, averaging between 3.1-3.8 million cases per year. Chicken pox can occur at any time of year.
Chicken pox is acquired by direct contact with infected blister fluid or by inhalation of respiratory droplets from an infected individual. When individuals with chicken pox cough or sneeze, they expel tiny droplets that carry the varicella virus. A person who has never been exposed to chicken pox then inhales these droplets, and the virus enters the lungs. It then is carried through the bloodstream to the skin, where it causes a rash.
While the virus is in the bloodstream (before the rash begins), it causes typical viral symptoms such as fever, fatigue, joint pains, headache, and swollen glands. These symptoms usually resolve by the time the rash develops. The incubation period (the time before the full-blown symptoms of the virus appear) of chicken pox averages 14 days, with a range of 10-21 days.
The chicken pox rash usually begins on the trunk of the body and spreads to the face and extremities. The chicken pox lesion starts as a 2-4-millimeter red papule that develops an irregular outline (similar to a rose petal). A thin-walled, clear vesicle (a blister that looks like a dew drop) develops on top of the area of redness. This lesion is unique to chicken pox. After about 8-12 hours, the fluid in the vesicle gets cloudy and the vesicle breaks, leaving a crust. The fluid is highly contagious, but once the lesion crusts over, it is not considered contagious. The crust usually falls off after seven days, sometimes leaving a craterlike scar. Although one lesion goes through this complete cycle in about seven days, another hallmark of chicken pox is the fact that new lesions can crop up every day for several days. Therefore, it may take about a week until new lesions stop appearing and existing lesions crust over. Children should not be sent back to school until all lesions have crusted over.
The number of chicken pox lesions a person gets varies considerably. The usual range is 100-300 lesions. Usually, older children and adults develop more lesions than young children. Individuals who have previously traumatized skin, such as sunburn or eczema, may also develop more severe lesions.
In addition to affecting the skin, chicken pox can also cause lesions on the mucous membranes in the eyes, mouth, throat, and vagina.
There is a varicella-zoster vaccine for use in individuals aged 12 months through 12 years. The chicken pox vaccine is a live attenuated vaccine, meaning the live, disease-producing virus was modified or weakened in the laboratory to produce an organism that can grow and produce immunity in the body without causing illness.
Shingles: Shingles (also called herpes zoster) is a disease caused by a reactivation of the varicella-zoster virus (VZV), the same virus that causes chicken pox. After an individual develops the VZV, it remains dormant within the nerve roots (nerve tissue). Outbreaks are then termed shingles. Shingles affects an estimated one out of every three people in the United States. More than one million people in the Unites States develop shingles annually. It is most common in individuals over the age of 60 and those who have previously had chicken pox. Shingles is also more common in individuals with weakened immune systems, which can result from HIV infection, radiation treatment, certain medications (including steroids and chemotherapy), and high levels of or chronic (long-term) stress.
The first sign of shingles is often burning or tingling pain, or sometimes numbness or itch, in a particular location on only one side of the face or body. After 1-5 days, a rash of fluid-filled blisters (similar to chicken pox) appears in the affected location. Shingles pain can be mild or severe. Some individuals experience only itching, while others feel pain from a gentle touch or breeze. The most common location for shingles is a band, called a dermatome, spanning one side of the trunk around the waistline. Other possible symptoms of shingles may include fever, headache, chills, or upset stomach. In rare cases, shingles may lead to eye complications (including blindness), pneumonia, hearing problems, encephalitis (brain inflammation), or death. Anyone who has had chicken pox is at risk for developing shingles at some point in their lives.
There is no cure for shingles. Early treatment with drugs that fight the virus may help. These medicines may also help prevent lingering pain. There is a vaccine now available (Zostavax®) that may prevent shingles or lessen its effects. The vaccine is for people aged 60 or over who have had chicken pox but who have not had shingles.
Postherpetic neuralgia: Some individuals continue to feel pain long after the shingles rash and blisters heal. This condition is termed postherpetic neuralgia (PHN). Not everyone who has had a recurrence of the virus develops PHN. Postherpetic neuralgia is a common complication of shingles in older adults but rarely occurs in people under the age of 40. The primary symptom of PHN is pain that can be debilitating. The pain associated with PHN may be aching, throbbing, stabbing, sharp, or piercing. Stress may intensify the severity of the pain. The intensity of the pain can vary, but pain-free intervals are rare. Some individuals who have had PHN describe the pain as the worst pain they have ever felt. The greater the age when the virus reactivates, the greater the chance the individual will develop PHN. In most individuals, the pain of PHN lessens over time, resolving itself in a few weeks or months. Treatments for PHN that may ease nerve-related pain include antidepressants (such as amitriptyline or Elavil®), anticonvulsants (such as gabapentin or Neurontin®), steroids (such as prednisone or Deltasone®), painkillers (such as opiates, including oxycodone or Percocet®), and topical anesthetic patches (such as lidocaine or Lidoderm®).
Human herpesvirus type 4 (HHV-4) :
Epstein-Barr virus (EBV): Epstein-Barr virus is a herpes virus (human herpesvirus type 4) that causes a viral syndrome referred to as mononucleosis. EBV has also been found to play a role in the development of Burkitt's lymphoma (a rare cancer of the lymph system) and nasopharyngeal carcinoma (cancer of the nose and throat) in humans. Mononucleosis (also known as mono, kissing disease, and Epstein-Barr viral syndrome) causes fever, a sore throat, swollen lymph glands (especially in the neck), and extreme fatigue (tiredness). Although typically caused by the Epstein-Barr virus (EBV), mononucleosis can also be caused by other herpes viruses, including cytomegalovirus (CMV). As many as 95% of adults 35-40 years of age have been infected with EBV in the United States. Infants become susceptible to EBV once antibodies against EBV, which are provided by the mother before birth, disappear. Infection with EBV during adolescence or young adulthood results in mononucleosis in 35-50% of cases. The incubation period for mononucleosis is usually 7-14 days in children and adolescents. The incubation period in adults is longer; at times, it may be 30-50 days. If symptoms of mononucleosis last more than six months, it is frequently referred to as chronic EBV infection. EBV may be linked to chronic fatigue syndrome (CFS), a condition of chronic tiredness and exhaustion.
Mononucleosis spreads by contact with moisture from the mouth and throat of a person who is infected with the virus. Kissing, touching anything that has been near the mouth of an infected person, or sharing drinking glasses, eating utensils, or toothbrushes may result in transmission of the disease. The infection develops slowly, with such mild symptoms initially that it may be mistaken for a cold or the flu. As the condition progresses, the symptoms may include a sore throat that lasts two weeks or more, swollen lymph nodes (in the neck, armpits, and groin), a persistent fever, fatigue, and malaise (a vague feeling of discomfort). These symptoms can be mild or so severe that throat pain impedes swallowing and fever reaches 105 degrees Fahrenheit. Some people also experience a rash, eye pain, photophobia (discomfort with bright light), and a swollen spleen or liver. In most cases of mononucleosis, no specific treatment is necessary, as the illness is usually self-limiting. While the symptoms of infectious mononucleosis usually resolve in one or two months, an individual infected by the EBV carries dormant cells in the throat and blood for the rest of his or her life. Periodically, the virus can reactivate and can be found in the saliva of infected persons. This reactivation usually occurs without symptoms of illness, although it may be linked to symptoms of CFS. EBV also establishes a lifelong dormant infection in some cells of the body's immune system.
Human herpesvirus type 5 (HHV-5) :
Cytomegalovirus (CMV): The cytomegalovirus is a herpes virus (human herpesvirus type 5) found in body fluids, including urine, saliva (spit), breast milk, blood, tears, semen, and vaginal fluids. CMV is one of the most common congenital (present at birth) infections in newborns in the United States. Congenital CMV infections affect approximately 35,000 infants each year in the United States, and approximately 5,500 of these infants later experience CMV-related disabilities. The virus is commonly transmitted from an infected pregnant woman to her unborn child. It is an opportunistic virus that does not usually cause disease in those with healthy immune systems. In people with weakened immune systems (such as those with HIV or AIDS), CMV can cause any number of infections, including retinitis (inflammation of the retina), pneumonia, colitis (inflammation of the colon), encephalitis (inflammation of the brain), mononucleosis, pneumonia, hepatitis, and uveitis. CMV syndrome and fever of unknown origin (known as pyrexia) are complications that may occur. CMV is a common a cause of serious disability, such as neural tube defects. Neural tube defects (NTDs) are serious birth defects with symptoms that range from mild to severe impairment. They are caused by incomplete development of the brain, spinal cord, and/or their protective coverings. Spina bifida is the most common neural tube defect. Spina bifida occurs when the spine fails to close properly during the first few weeks of pregnancy, causing damage to the nerves and spinal cord. It is estimated that more than 70,000 people in the United States are living with spina bifida.
Other herpes viruses :
Human herpesvirus type 6 (HHV-6): Human herpesvirus type 6 has been linked to two conditions, roseola and lymphotrophic virus. HHV-6 has also been considered as a possible cause of chronic fatigue syndrome (CFS), along with HHV-3 (varicella-zoster). CFS patients can have extremely high levels of antibodies to HHV-6, meaning that an infection is present. HHV-6 infection is a major cause of opportunistic viral infections in patients with compromised immune systems, especially due to AIDS or organ transplants. HHV-6 may cause rejection of transplanted organs and death. HHV-6 may also be a cause of multiple sclerosis (MS), a chronic (long-term) inflammatory condition of the central nervous system (CNS) resulting in changes in sensation, visual problems, muscle weakness, depression, difficulties with coordination and speech, severe fatigue, cognitive impairment, problems with balance, overheating, and pain. MS causes impaired mobility and disability in more severe cases.
Roseola (also known as sixth disease, exanthem subitum, and roseola infantum) is a viral illness in young children, most commonly affecting those between the ages of six months and two years. It is typically marked by several days of high fever (over 102 degrees Fahrenheit), followed by a distinctive rash that occurs when the fever breaks.
There are two different types of HHV-6, the first type being responsible for roseola and the second responsible for infections in adults with weakened immune systems due to HIV/AIDS or cancer. This is the type that is thought to be associated with chronic fatigue syndrome (CFS).
Human herpesvirus type 7 (HHV-7): Human herpesvirus type 7 is closely related to both HHV-6 and cytomegalovirus (CMV). Of the three viruses, HHV-7 is the least pathogenic (disease-causing). Like HHV-6, HHV-7 primarily causes roseola in infants and young children, which is a febrile (fever) illness that typically lasts for six days.
Human herpesvirus type 8 (HHV-8): Human herpesvirus type 8 is a type of herpes virus responsible for diseases such as Kaposi's sarcoma (KS), lymphoproliferative disorders (when too many white blood cells are produced), primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD). This virus only attacks individuals with weakened immune systems, such as those with HIV and AIDS. The virus has been identified in all types of KS, including classic, endemic, post-transplant, and AIDS-related KS, all of which have identical features under the microscope. Research suggests that HHV-8 infection is spread by mouth-to-mouth contact (kissing) or genital contact. Previous studies on Kaposi's sarcoma have indicated that HHV-8 was more commonly found in saliva than in genital secretions.