There are two types of herpes simplex viruses (HSV), they are termed HSV-1 and HSV-2. These two viruses have distinctly different DNA, and both cause oral and genital lesions. However, HSV-1 causes about 80% of all oral lesions and only about 20% of genital lesions while HSV-2 causes the reverse (about 80% genital and 20% oral). Studies also suggest that in adolescents, up to 40% of genital herpes is caused by HSV-1 because of reported increased oral/genital contact (transmission by oral sex).
After exposure to the virus, many people experience a so called primary infection which is typically associated with sores on or around the genitals or the anus. During a primary infection some people experience pain in the groins or a mild fever. Not all infected individuals experience a primary infection or show any symptoms at all, but they can still pass the disease on to other people.
It can be pretty similar to having flu, Michael says. "When you are infected with herpes you can experience symptoms like fever, muscle aches, swollen lymph nodes, and a general feeling of being unwell." However, many people will not have any symptoms at all - which means until someone notices blisters or sores, they might not realise they have a herpes infection.
Mouth herpes{also known as oral herpes) primarily affects children of more than 6 months of age or who are aged 1-2 years  and it affects adults also.  When this virus is inside your mouth it is sometimes confused with a canker sore. It results in painful red fluid-filled blisters or lesions on the tongue, lips, inside of the cheeks, and gums often accompanied with an itchy or burning sensation. Muscle pain and fever can also be suffered at a later stage.  If treatment is ignored, a herpes infection inside your mouth can be dangerous.
Human herpes virus 5 (HHV5) is the official name of cytomegalovirus (CMV). CMV is also a cause of mononucleosis. In people with healthy immune systems, the virus may not even cause any symptoms. It can be sexually transmitted, can cause problems to newborns, and can cause hepatitis. CMV can be transmitted through sexual contact, breast-feeding, blood transfusions, and organ transplants. CMV infection is one of the most difficult complications of AIDS. It may lead to diarrhea, severe vision problems including blindness, infections of the stomach and intestines, and even death. For a virus that barely causes a problem in most people with healthy immune systems, it can be amazingly nasty in people with damaged immune systems, such as people with AIDS.
Prescription antiviral medications are also commonly used to reduce the duration, severity, and incidence of outbreak. These medications include (but are not limited to) valacyclovir, acyclovir, and famciclovir. Remember that these medications will not cure HSV-1 or HSV-2. Instead, they will help reduce the amount of time the outbreak is present, and help control the severity of symptoms.
However, asymptomatic carriers of the HSV-2 virus are still contagious. In many infections, the first symptom people will have of their own infections is the horizontal transmission to a sexual partner or the vertical transmission of neonatal herpes to a newborn at term. Since most asymptomatic individuals are unaware of their infection, they are considered at high risk for spreading HSV.[47]
Worldwide rates of either HSV-1 and/or HSV-2 are between 60 and 95% in adults.[4] HSV-1 is more common than HSV-2, with rates of both increasing as people age.[4] HSV-1 rates are between 70% and 80% in populations of low socioeconomic status and 40% to 60% in populations of improved socioeconomic status.[4] An estimated 536 million people or 16% of the population worldwide were infected with HSV-2 as of 2003 with greater rates among women and in those in the developing world.[10] Rates of infection are determined by the presence of antibodies against either viral species.[81]
At the other end of the spectrum, there is a possibility of a herpetic flare up taking a sinister turn and leading to herpetic encephalitis. It is estimated to affect at least 1 in 500,000 individuals per year. The mechanism of this is not fully understood, but it is believed that the infection occurs through direct transmission of the virus via nerves from other parts of the body to the brain. In such cases, a person may complain of fever, headache, and lethargy, followed by confusion or delirium. In some cases, some people even develop seizures. This requires immediate medical attention and treatment.
Worldwide rates of either HSV-1 and/or HSV-2 are between 60 and 95% in adults.[4] HSV-1 is more common than HSV-2, with rates of both increasing as people age.[4] HSV-1 rates are between 70% and 80% in populations of low socioeconomic status and 40% to 60% in populations of improved socioeconomic status.[4] An estimated 536 million people or 16% of the population worldwide were infected with HSV-2 as of 2003 with greater rates among women and in those in the developing world.[10] Rates of infection are determined by the presence of antibodies against either viral species.[81]
Genital herpes is contracted through sexual activity, and may show symptoms around the genital area (anus, buttocks, thigh, penis, vulva, etc.). Additionally, people with HIV can experience significantly worse symptoms of herpes.  See a doctor if your partner has herpes, or if you notice any unusual sores on your body.  How do you know if you have herpes?  Read more in our Diagnosing Herpes section here.  

The broader issue is whether, if you do get infected, herpes will ultimately harm your health. Although I don’t want to trivialize this infection, in your general scheme of health, it probably will not. The major concern is that if you are pregnant and develop a new outbreak of herpes, the virus can be transmitted to the fetus, especially during vaginal delivery. What’s more, people with genital herpes have a much greater risk of acquiring HIV if they are exposed. (It’s theorized that the lesion causes microscopic breaks in the skin, allowing HIV to enter the body.)
Herpes simplex is a viral infection caused by the herpes simplex virus.[1] Infections are categorized based on the part of the body infected. Oral herpes involves the face or mouth. It may result in small blisters in groups often called cold sores or fever blisters or may just cause a sore throat.[2][5] Genital herpes, often simply known as herpes, may have minimal symptoms or form blisters that break open and result in small ulcers.[1] These typically heal over two to four weeks.[1] Tingling or shooting pains may occur before the blisters appear.[1] Herpes cycles between periods of active disease followed by periods without symptoms.[1] The first episode is often more severe and may be associated with fever, muscle pains, swollen lymph nodes and headaches.[1] Over time, episodes of active disease decrease in frequency and severity.[1] Other disorders caused by herpes simplex include: herpetic whitlow when it involves the fingers,[6] herpes of the eye,[7] herpes infection of the brain,[8] and neonatal herpes when it affects a newborn, among others.[9]
As of 2017, there is not currently a herpes vaccine available to prevent HSV-1 or HSV-2. (There is a vaccine available for another virus, herpes zoster; however, despite the similar name, it actually refers to the shingles virus. And, in fact, shingles occurs due to the reactivation of yet another virus, varicella zoster, which causes chicken pox.)
Do everything possible to prevent spreading it to other people. The virus cannot live long when it is not in contact with the skin, so door handles and towels are not likely to spread it. Do not share your personal belongings, like toothbrushes and combs.  Wash your hands with soap and water often, and immediately if you touch the sores.  This is important so as to minimize the chance of getting ocular herpes (herpes infection of the eye) which is a serious infection. Be especially careful around infants because their immune systems may not be fully developed. Little children often express affection with sloppy wet kisses. This is a common way to spread the herpes virus within the family.
A 2004 study in the New England Journal of Medicine found that suppressive therapy decreases the risk of HSV-2 transmission from symptomatic, infected partners to uninfected partners by 48%. So “the risk of transmission is significantly reduced, but cannot be eliminated even with suppressive therapy,” Johnston explains, and she stresses that the virus can be passed along even without signs or symptoms.
×