Types of Herpes Viruses
Herpes viruses belong to a viral family called herpesviridae, numbered HHV (human herpesvirus) 1-8. These viruses lead to a number of conditions, including oral herpes, genital herpes, chickenpox and shingles, Epstein-Barr, cytomegalovirus, roseolovirus and Kaposi's sarcoma-associated herpesvirus. Herpes viruses share some common features, such as causing lifelong infections which cannot be cured; however, they lead to a number of different effects which vary in manifestation and severity.
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Oral Herpes
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HHV-1, also known as HSV-1 (herpes simplex 1), is the virus that causes oral herpes, also known as cold sores; the condition is also sometimes, though rarely, triggered by HSV-2, the virus that causes genital herpes.
HSV-1 is one of the herpes viruses that remains latent in nerve cells and then causes skin symptoms around the area of the nerve in which it is dormant (the other type of herpes virus remains dormant in cells of the immune system). HSV-1 can be transmitted through contact with skin affected by active blisters. According to the Mayo Clinic, other routes of transmission include sharing items like dishes and lip-care products. The Mayo Clinic also reports that people with weakened immune systems can contract the virus even after cold sores have cleared.
As with other herpetic conditions, people with HSV-1 experience prodrome before an outbreak; these symptoms include a burning, tingling or itching sensation before cold sores develop. Antiviral treatment for cold sores includes antiviral drugs like acyclovir, valacyclovir or famciclovir and are most effective when begun during this prodrome. The Mayo Clinic also reports the use of topical lidocaine and benzyl alcohol for relief. Cold sores also subside quickly on their own, even without treatment.
Genital Herpes
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Genital herpes is caused by HHV-2 (HSV-2) and sometimes, though much more rarely, by HSV-1. Like HSV-1, HSV-2 becomes dormant after infection in nerve cells and causes blisters in the skin around the nerve in which it is latent.
HSV-2 can be transmitted through close contact with affected skin, with or without the presence of an outbreak. The ability of the virus to spread in the absence of an outbreak is called asymptomatic viral shedding. Treatment for genital herpes includes antiviral drugs; the use of topical agents is not recommended. People who have frequent outbreaks may be put on daily suppressive therapy, which decreases one's chances of developing an outbreak as well as the risk of transmitting the virus to one's sexual partners. Although the use of condoms is recommended to decrease the risk of transmitting or contracting genital herpes and other STDs, HSV-2 can be transmitted through skin that is not covered by a condom.
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Chickenpox
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Chickenpox is caused by the varicella-zoster virus (VZV), also known as HHV-3; this same virus is responsible for shingles when it flares up later. The first infection of VZV causes chickenpox, never shingles, no matter at what age one contracts the virus; only the recurrence of VZV leads to shingles. Like HHV-1 and HHV-2, VZV becomes dormant in nerve cells.
VZV is only infectious to people who have not already had chickenpox. The virus is easily transmitted through the sores it causes or through coughing and sneezing. There is an effective vaccine against VZV. According to the Centers for Disease Control and Prevention (CDC), between eight and nine out of 10 people who are vaccinated do not develop chickenpox and those that do experience milder symptoms.
Shingles and PHN
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A recurrence of VZV leads to a condition known as shingles or herpes zoster. This condition is more painful and less itchy than chickenpox, and is characterized by a skin rash and often severe pain following the course of the nerve in which VZV had been dormant. Treatment for shingles includes antiviral drugs along with corticosteroids to reduce nerve inflammation and damage. Other treatments include the use of painkillers, either over-the-counter or narcotic depending on the severity of the pain, and topical relief from calamine lotion and capsaicin cream.
In some people, the pain of shingles remains after the skin rash has gone away. This is a condition that is known as postherpetic neuralgia (PHN), and the pain of this condition is quite severe. It is treated with lowered-dose tricyclic antidepressants and anticonvulsants as well as narcotic painkillers, continued use of corticosteroids and other methods like electrode nerve stimulation.
Others
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Herpes viruses cause other, lesser-known conditions, including Epstein-Barr, cytomegalovirus, roseolovirus and Kaposi's sarcoma-associated herpesvirus. All of these herpes viruses become latent in cells of the immune system.
Epstein-Barr (HHV-4) is a common virus that causes no symptoms when contracted in childhood; however, it often leads to mononucleosis when contracted by young adults. Cytomegalovirus (HHV-5 or CMV) is similarly common and generally causes no symptoms; however, the CDC reports that when a pregnant woman passes CMV along to her child that the child is at risk for congenital disabilities. CMV can also lead to visual impairment and other problems in HIV-positive people or those with compromised immune systems. HHV-6 and HHV-7 both lead to roseola, which causes fever and rash in children. HHV-8, or Kaposi's sarcoma-associated herpesvirus leads to Kaposi's sarcoma, a skin cancer found in people living with AIDS and in some other populations.
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