Epidemiology of Gential Herpes
... A genital infection with type 1 HSV has an average recurrence rate of about once per year, while a genital HSV-2 infection has an average recurrence rate of about 5 times per year. An oral infection with type 2 HSV will rarely, if ever, recur. The difference between "genital" Herpes and "oral" Herpes is in location only, not viral type. Many people mistakenly refer to type 2 as "genital herpes," and type 1 as "oral herpes," when in fact, Herpes types 1 and 2 can and do infect either area. While many people have type 1 oral infections and type 1 or 2 genital infections as well, it is rare for a person to have infections with type 1 and type 2 together in the same location. Its possible to be infected by both HSV1 and HSV2, but being infected by one strand doesn’t immune you from another. During the first initial infection symptoms are usually the most severe as the body may not have been exposed to the virus before and antibodies will not have been produced to trigger the immune response. The initial genital herpes episode can last for more than 20 days and it is not uncommon for someone to experience a range of generalized symptoms, such as fever, aches and pains, swollen lymph nodes, as well as specific genital symptoms. Symptoms such as fever, headache, and depression are present in two thirds of women and approximately 40 percent of men with such a clinically evident first episode. For others, the initial infection can be mild with minimal symptoms. For most people, the first indication of infection starts between two to 12 days after exposure to the virus. The development of symptoms may take longer or be less severe in some people, especially those who have previously developed partial resistance to the virus from having facial herpes, cold sores. Symptoms can start with tingling, itching, burning or pain followed by the appearance of painful red spots which, within a day or two, evolve through a phase of clear, fluid-filled blisters which rapidly turn whitish-yellow. The blisters burst, leaving painful ulcers that dry, scab over and heal in approximately 10 days. Such symptoms occur in 16 percent of recognized cases of non-primary infections and 62 percent of recognized cases of primary infections. Non-primary infections are also associated with lower rates of complications than primary infections, a shorter duration of disease. Sometimes the development of new blisters at the early ulcer stage can prolong the episode. On the other hand, the blister stage may be missed completely and ulcers may appear like small cuts or cracks in the skin. Women particularly often experience pain on urinating, and when this happens, it's important to avoid problems of urinary retention by drinking plenty of fluids to dilute the urine and thereby reduce pain and stinging. Some women may also notice vaginal discharge. Some people do not experience symptomatic recurrences but for those who do, recurrences are usually shorter and less severe than the initial episode. Over time, recurrences may decrease in both severity and frequency, although there is no definite evidence that this happens. Warning symptoms, also known as prodromal symptoms, such as tingling, itching, burning or pain, usually precedes recurrences. As with the initial episode, there is a large variation in people's experiences of recurrences. Approximately 80% of persons having a first episode caused by HSV-2 will have at least one recurrence, while only 50% of persons with HSV-1 will experience a recurrence. The most common scenario is occasional recurrences (about 4 attacks per year). However, a minority will more suffer frequent recurrences. Within 12 months after diagnosis of genital herpes, 90 percent of patients with a documented first episode of genital HSV-2 infection have at least 1 recurrence, 38 percent have 6 or more recurrences, and 20 percent have 10 or more recurrences. A recurrence takes place when the virus replicates in nerve ganglia and particles of virus travel along the nerve to the site of primary infection in the skin or mucous membranes, the inner moist lining of the mouth, and vagina. Although it is not known exactly why the virus reactivates at various times, causal factors can be separated into the physical and the psychological. Physical factors differ from person to person. Tiredness, suffering from other local skin infections, menstruation, drinking a lot of alcohol, exposure of the area to strong sunlight, conditions that make a person immune system not functioning normally, and ultraviolet light, are all factors that can trigger an episode. Friction or damage to the skin, caused by, for example, sexual intercourse, may also lead to a recurrence. Physiological factors also initiate recurrent outbreaks. Recent studies suggest that periods of prolonged stress can cause more frequent recurrences. It is also common to experience stress and anxiety as a result of having recurrences. Up to 1 million new HSV-2 infections may be transmitted each year in the United States. There are three ways in which this virus can be transmitted; direct contact self-infection and vertical transmission. Genital herpes can be transmitted through direct contact by way of sexual intercourse, and oral sex. The mucous membranes, genitals and anus, are most susceptible to infection with HSV-2. The cervix and urethra are also high target areas as well as areas that may be subject to abrasion, and warm, moist areas were sweating is common such as the perineum, scrotum, and buttocks. Herpes is most easily passed through from active lesions. The virus may also spread during times when there are no symptoms, and from sites that are seemingly inactive. Most incidences of genital Herpes occur during sexual intercourse. There are however, a significant percentage of genital herpes infections resulting from oral to genital sexual contact. HSV-1 is responsible for only 5-10% of genital herpes cases, while HSV-2 causes the majority of genital herpes cases. HSV-2 can be transmitted through oral or genital secretions. An estimated 86 million people worldwide are thought to have genital herpes. Self-infection can occur by transferring the virus from one part of the body to another, usually via touching a sore with a hand and then touching another susceptible area, such as the mouth or eyes. This complication is more common during a first episode because of higher amounts of virus present during that time. According to the American Social Health Association (ASHA), between 20% and 25% of pregnant women have genital herpes. Women who acquire genital herpes before becoming pregnant have a lower risk of vertical transmission than women who acquire genital herpes during pregnancy. Women who acquire genital herpes during their third trimester of pregnancy have a higher chance of vertical transmission because their body has not developed antibodies to the virus, thus causing neonatal HSV-2. Overall frequency of neonatal HSV is about 1 in 7500 live births, or about 500 cases per year. The major source of infection is viral shedding in the genital tract, during delivery. Vaginal delivery during primary infection may carry a 50 percent risk of neonatal infection, with significant morbidity and mortality. Up to 70 percent of infected neonates come from mothers who are asymptomatic at delivery. Overall, a woman with a past history of genital HSV, but no active lesions at delivery, has a 1:1000 chance of infecting the baby. There are several tests that are used to diagnose herpes; some are more accurate than others. Viral culture is where the virus is grown in material known as a culture medium. Viral culture looks for the presence of the virus in the lesion. Viral cultures are very specific: · It does not frequently give a positive result when something else is the culprit · It can also be very sensitive if the specimen is sufficient · It also provides a way to tell whether the infection is caused by HSV-1 or HSV-2 A poor sample may cause sensitivity to drop. Even if herpes lesions are present, there may be very little active virus l ft in the lesions. In this case, the culture will come back as a "false negative" (the test says there is no herpes even when the patient has genital herpes). Often about 20% of culture tests produce a "false negative" when a patient has a first episode of herpes. With recurrent episodes, when very little of the virus is present, the rate of false negatives goes up to 50%. Serologic tests (blood tests) detect herpes by looking for antibodies in the blood or serum. Blood tests can be performed even when no symptoms are present. If antibodies are found in the blood, herpes simplex is latent in the body. Blood tests do not require swabbing a lesion, so they can be done long after symptoms have faded. Serologic testing has the advantage that it can be done even when a person has no symptoms, so it is a very effective way to detect an established herpes infection. The sensitivity and specificity of blood tests is better than culture or antigen tests, but there are two important factors to consider. The first factor is timing. If this is the first exposure to herpes, a person may take several weeks to develop the antibodies that the test looks for. The second is that some blood tests cannot tell the difference between the two types of herpes, HSV-1 and HSV-2. The third type of test, the antigen test, is used less frequently and also looks for the presence of virus in the lesion. Unlike the culture method, this test does n...