Herpes is a common viral infection caused by the herpes simplex virus (HSV). The virus exists as two main types, HSV-1 and HSV-2.
HSV testing identifies the presence of the virus in a sample from a blister, sore or fluid to diagnose an active herpes infection or testing detects antibodies in the blood to determine previous exposure to herpes.
Both HSV-1 and HSV-2 are contagious and periodically cause small fever blisters (vesicles) that break to form open lesions.
HSV-1 primarily causes blisters or "cold sores" around the mouth (non-genital sites).
HSV-2 usually causes lesions around the genital area.
However, both HSV-1 and HSV-2 can affect either the oral or genital areas.
The herpes simplex virus can be passed from person-to-person through skin contact while the sores are open and healing and sometimes when there are no visible sores. HSV-2 is the type most often spread during sex, but HSV-1 may also infect the genital area during oral sex.
Most people who have HSV-2 are unaware they are infected because signs and symptoms may be mild and go unnoticed.
When symptoms do appear, they may begin as painful blisters at the site of infection, usually within two weeks after infection.
- The blisters can appear around the mouth, in the vaginal area, on the penis, around the anus, or on the buttocks or thighs.
- The blisters generally heal within two to four weeks.
This primary episode can include a second outbreak of blisters and even flu-like symptoms such as fever and swollen glands. However, not everyone develops blisters and sometimes symptoms are so mild that they are unnoticeable or mistaken for something else, such as insect bites or a rash. Once you are infected and the initial infection resolves, the virus remains in your body in a latent form for the rest of your life. During periods of stress or illness, the virus may reactivate and you may have periodic outbreaks. People with weakened immune systems, such as those with HIV/AIDS or those who have had an organ transplant, may have more frequent and serious outbreaks of HSV.
What about treatment:
There is no cure for herpes, but antiviral medications such as acyclovir, famciclovir and valacyclovir can suppress outbreaks and shorten the duration of symptoms and active shedding of the virus.
Rarely, the virus can cause infections in newborns (neonatal herpes) when a mother transmits the virus to her baby during a vaginal delivery. Neonatal herpes symptoms appear during the first month of life. If left untreated, herpes can cause long-term health problems in the baby and can be life-threatening. A pregnant woman who has been diagnosed with herpes may be monitored regularly prior to delivery to detect a reactivation of her infection.
A HSV infection can spread to the brain, causing encephalitis. This illness can be fatal or cause serious, permanent neurological problems in those who survive.
Herpes may be tested a few different ways:
Direct detection of the virus: The preferred methods of testing for the virus in people with active blisters or sores are the herpes culture and HSV PCR testing. PCR testing is the preferred method if encephalitis or neonatal herpes are suspected.
HSV DNA PCR (NAAT): this method detects HSV genetic material in a sample from the blister, blood, or other fluid, such as spinal fluid. PCR can detect the virus as well as identify the type of herpes virus (HSV-1 or HSV-2). This method is more sensitive than culture and is becoming more widely available.
Herpes culture: a sample of fluid is collected from an open sore using a swab and cultured. If the culture is positive, the virus can be further identified as HSV-1 or HSV-2.
Antibody testing: HSV antibody (serologic) testing detects immune proteins called immunoglobulin G (IgG) in your blood that the body produces in response to a herpes infection. HSV antibody testing can detect both HSV-1 and HSV-2 antibodies as well as differentiate between them.
It can be difficult to decipher IgG and IgM results when performed together. It's important to remember that IgG antibodies take longer to produce but last a lifetime, while IgM antibodies are detectable after a few days but dissipate within a few weeks.
If you test positive for IgG but not IgM, you have probably been infected for at least two months. People with newer infections are more likely to test positive for IgG and IgM or just IgM alone.
Having positive IgG and IgM results doesn't necessarily mean that you were infected recently. In fact, between 30 and 70 percent of people with recurrent infections will test positive for IgM, according to a 2014 review published in the Virology Journal. [L]
|Positive IgG||Negative IgG|
|Positive IgM||Infection date indeterminate||Acute/Recent infection|
|Negative IgM||Established Infection||No infection detected|
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