Herpes viruses

background

Herpes is a group of viruses that infect humans. Types of herpes viruses include herpes simplex virus types 1 and 2 (HHV-1 and HHV-2 respectively), human herpesvirus type 3 (varicella-zoster virus), human herpesvirus type 4 (including Epstein-Barr virus and lymphocryptovirus), human herpesvirus type 5 (cytomegalovirus), human herpesviruse type 6 (HHV-6, including human B-cell lymphotrophic virus and roseolovirus), human herpesvirus type 7 (HHV-7), and human herpesvirus type 8 (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 type 1 (HHV-1) is also known as a cold sore or fever blister. Herpes simplex type 2 (HHV-2) is also known as genital herpes. Human herpes virus 3 is also referred to as varicella-zoster or VZV. Herpes varicella is the primary infection that causes chickenpox, and herpes zoster is the reactivation of the varicella virus that causes shingles.
Herpes 1 and 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 the HSV virus.
Herpes is a contagious infection that spreads when the carrier is producing and releasing ("shedding") 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, 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 (genital-to-genital, mouth-to-genital, or hand-to-genital; not kissing) with an infected partner. 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 on their genitals should avoid oral sex. The varicella-zoster (chickenpox) 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 genitals, mouth, and lips). At some point this latency ends, and the virus becomes active again. While active, the virus begins to multiply (called shedding), and becomes transmittable again. This shedding may or may not be accompanied by symptoms. During reactivation, virus is produced in the nerve cell and transported outwardly via the nerve to the skin. The ability of herpes virus to become latent and reactive explains the chronic (long-term), recurring 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, illness with fever, stress, immune system imbalances, and other unknown causes.

synonyms

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-Barre syndrome, hepatitis, herpes labialis, herpetic, herpes zoster ophthalmicus, HHV-2, HHV-4, HHV-5, HHV-6, HHV-7, 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 7, human herpesvirus type 8, human herpesviruse type 6, 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, opcular lesions, oropharyngeal, PCR, PEL, PHN, pneumonia, polymerase chain reaction, postherpetic neuralgia, primary effusion lymphoma, prodromal, pyrexia, Ramsay Hunt syndrome, retinitis, rhadinovirus, roseola infantum, roseola, 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 1 (HSV-1) and herpes simplex virus 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 (HSV-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. It is thought that 90% of adults have been exposed to the virus during a lifetime, and most Americans are infected by the age of 20. 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 or two weeks and as late as three weeks after contact with an infected person. The lesions of herpes labialis usually last for seven to 10 days then begin to resolve. 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.
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 than HSV-2
Herpes simplex virus type 2 (HSV-2): HSV-2 is considered the primary cause of genital herpes. In the United States, at least 45 million people ages 12 and older have had herpes simplex virus type 2 (HSV-2 or genital herpes) infection. According to researchers at the Centers for Disease Control and Prevention (CDC), HSV is present in as many as one in six teens and adults in the United States.
HSV-2 is a sexually transmitted disease (STD), meaning an individual must engage in sexual activity (oral or manual sex or intercourse) in order to transmit or be infected with this virus. HSV-2 infection is more common in women (approximately one out of four women) than in men (almost one out of five). This may be because male-to-female transmissions are more likely than female-to-male transmission. Anyone who is sexually active can 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.
Most individuals infected with HSV-2 are not aware of their infection. However, if signs and symptoms occur during the first outbreak, they can be quite severe. The first outbreak usually occurs within two weeks after the virus is transmitted, and the sores typically heal within two to four weeks. Other signs and symptoms during the primary episode may include a second crop of sores and flu-like symptoms, including fever and swollen glands. However, many individuals with HSV-2 infection may never have sores, or they may have very mild sores that they do not even notice or that they mistake for insect bites or another skin condition.
Most people diagnosed with a first episode of genital herpes can expect to have four to five outbreaks (called symptomatic recurrences) within a year. Over time these recurrences usually decrease in frequency. 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 their partner is infected with HSV type 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. Symptoms of an active outbreak include blisters or ulcers. Some individuals may never have any symptoms and may not know that they are infected with the herpes virus. However, 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 in the facial area as well as genital herpes (similar symptoms in the genital region).
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 non-infected 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 chickenpox are caused by the 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 chickenpox) or herpes zoster (the reactivation of the virus that causes shingles). The human race is the only known carrier of HHV-3.
Chickenpox: Chickenpox is usually a childhood disease. Over 90% of cases occur in children aged 14 years and younger. Before widespread vaccination, the incidence of chickenpox in the United States. approached the annual birth rate, averaging between 3.1-3.8 million cases per year. Chickenpox can occur at any time of year.
Chickenpox is acquired by direct contact with infected blister fluid or by inhalation of respiratory droplets. When an individual with chickenpox coughs or sneezes, they expel tiny droplets that carry the varicella virus. A person who has never been exposed to chickenpox inhales these droplets and the virus enters the lungs, and 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 (time before the full blown symptoms of the virus appear) of chickenpox averages 14 days with a range of nine to 21 days.
The chickenpox rash usually begins on the trunk of the body and spreads to the face and extremities. The chickenpox lesion starts as a two to four 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 very unique to chickenpox. After about eight to 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 chickenpox 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 chickenpox 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, chickenpox 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 ages 12 months through 12 years. The chickenpox 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 the varicella-zoster virus (VZV), the same virus that causes chickenpox. After an individual develops the VZV, it remains dormant within the nerve roots (nerve tissue). Outbreaks are then termed shingles. Shingles affects an estimated two in every 10 people in their lifetime. More than 500,000 people in the Unites States develop shingles annually. It is most common in individuals over the age of 50 and those who have previously had chickenpox. 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), transplant operations, 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 one particular location on only one side of the body. After several days or a week, a rash of fluid-filled blisters (similar to chickenpox) appears in the affected location. Shingles pain can be mild or severe. Some individuals experience only itching, while others feel pain from 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. Anyone who has had chickenpox is at risk for developing shingles at some point in their lives.
There is no cure for shingles. Early treatment with antiviral drugs that fight the virus may help. These medicines may also help prevent lingering pain. There is a vaccine now available that may prevent shingles or lessen its effects (Zostavax®). The vaccine is for people 60 or over who have had chickenpox 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. But postherpetic neuralgia is a common complication of shingles in older adults. 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. Treatments for PHN that may ease nerve-related pain include: antidepressants (such as amitryptilline or Elavil®), anticonvulsants (such as gabapentin or Neurontin®), steroids (such as prednisone or Deltasone®), pain killers (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 (EBV) 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 form of lymphoma or cancer of the lymph system) and nasopharyngeal carcinoma (cancer of the nose and throat) in humans. The Epstein-Barr viral syndrome, 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 or tiredness. Although typically caused by the Epstein-Barr virus (EBV), mononucleosis can also be caused by other herpes viruses including cytomegalovirus (CMV). In the United States, as many as 95% of adults between 35-40 years of age have been infected with EBV. Infants become susceptible to EBV as soon as maternal protection present at birth disappears. Infection with EBV during adolescence or young adulthood results in mononucleosis in 35-50% of the cases. The incubation period for the mononucleosis is usually seven to 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, 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, sharing drinking glasses, eating utensils, and toothbrushes, or touching anything that has been near the mouth of an infected person, 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 (tiredness), 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. Although the symptoms of infectious mononucleosis usually resolve in one or two months, the EBV remains dormant in cells in the throat and blood for the rest of the person's 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 (CMV) is a herpes virus (human herpesvirus type 5) found in body fluids including urine, saliva (spit), breast milk, blood, tears, semen, and vaginal fluids. It 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 (HHV-6) has been linked to two conditions, roseola and lyphotrophic virus. HHV-6 has also been considered as a possible cause of chronic fatigue syndrome (CFS), along with HHV-3 or varicella zoster. CFS patients can have extremely high levels of antibodies to HHV-6, meaning there is an infection 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 will cause 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 (HHV-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 (HHV-8) is a type of herpes virus responsible for diseases such as Kaposi's sarcoma (KS), lymphoproliferative disorders (condition of too many white blood cells produced), primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD). This virus only attacks immunocompromised individuals, 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 suggest 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.