What Causes Herpes?
Either of two viruses can cause herpes: herpes simplex type 1 (HSV-1) and herpes simplex type 2 (HSV-2). Both are part of a larger family of "herpesviruses" that includes varicella zoster virus, the cause of chicken pox and shingles; and Epstein Barr virus, the cause of "mono."

Herpes simplex is different from many other common viral infections in several ways. Most importantly, herpes sets up a lifelong presence in the body. The virus can travel the nerve pathways in a particular part of the body and hide away in the nerve roots for long periods of time. This means that even though HSV may not be causing "cold sores" or genital symptoms at a given time, it can still cause symptoms later when HSV wakes up ("reactivates") and travels back to the skin.

What Are The Symptoms Of Oral Herpes?
The majority of oral herpes infections are caused by HSV-1, and most people contract oral herpes when they are young. This may occur when a child receives a kiss from a person who has a cold sore or from other childhood physical contact (daycare, etc.).

Many people with oral HSV do not have cold sores or other symptoms. It's estimated that only 20% to 40% of people with oral herpes have recurrent cold sores as adults.

Classic symptoms of oral herpes can appear as a single blister or cluster of blisters ("cold sores") on the lips but may also occur on other areas around the face such as the cheeks, chin, or nose. Subtle oral HSV symptoms can be easily mistaken for another infection or condition such as a small crack or cut in the skin, chapped lips, bug bite, or a pimple, to name a few examples.

What Are The Symptoms Of Genital Herpes?
Most often caused by HSV-2, symptoms of genital herpes vary greatly from one person to the next. The majority of people have such mild symptoms that they may not recognize the infection for many years. Out of the one in five adults (males and females) in the United States who have genital herpes, more than 80% have not been diagnosed and are unaware they have it.

The most noticeable symptoms tend to occur shortly after a person contracts the virus, when her or his immune response to herpes is not fully developed ("first episode"). Later symptoms tend to be milder because the immune response recognizes the virus and can quickly respond to it.

For some, symptoms during a first episode can be severe, appearing as small fluid filled blisters that crust over and scab like a small cut, sometimes taking more than two weeks to fully heal. Symptoms of a first episode may also include flu-like symptoms, such as fever and swollen glands, particularly in the groin. On the other hand, most people have first episode symptoms so mild they don't even notice them. It may be another episode, or "reactivation," that is first noticed months or even years later.

Right before an outbreak, many people experience an itching, tingling, or burning feeling in the area where their herpes symptoms will develop. This sort of warning symptom is called a "prodrome" and often precedes visible signs of infection by a day or two. In some people, prodrome will involve pain in the buttocks, the back of the legs, or even lower back.

How Is It That Herpes Symptoms Can Go Unrecognized?
Many people have very subtle forms of recurrent herpes that can heal in a matter of days. While recurrences of herpes may cause the classic blisters, other symptoms caused by HSV can easily be mistaken for insect bites, ingrown hairs, abrasions, yeast infections, "jock itch," hemorrhoids, and other conditions.

Can Herpes Be Active Without Causing Symptoms?
It was once thought that all of HSV's active times were marked by "outbreaks"-a sore, blister, bump, rash, or some other kind of symptom like an itch. However, researchers have learned that there are days when HSV can become active without causing symptoms. This is often called "asymptomatic viral shedding." And during these times, because there are no recognizable signs that the virus has made its way to the skin, there is no way of knowing when asymptomatic shedding is occurring.

How Is Herpes Transmitted?
Herpes is spread most efficiently by direct skin-to-skin contact. More specifically, the soft moist tissue of the mouth and genitals are most vulnerable to HSV if these areas come into contact with the virus.

The following scenarios illustrate how HSV is most often transmitted:

* If a person has a cold sore and kisses someone, the virus can be passed to the other person's mouth.

* If a person has active genital herpes and engages in direct genital-to-genital contact, the virus can be transmitted from her or his genitals to a partner's.

* If someone with a cold sore places his or her mouth on a partner's genitals (oral sex), the partner can contract genital herpes.

Herpes can be transmitted through sexual contact during asymptomatic viral shedding or times when there are no obvious symptoms. Herpes is often passed by people who do not know they have herpes, or by people who simply don't recognize that their herpes infection is in an active phase.

Can Herpes Be Prevented?
Preventing herpes can be a difficult challenge. First, HSV is widespread, with more than two out of three adults infected with HSV-1 or HSV-2. Second, most people who have HSV are unaware that they have the infection. And third, even among those who are aware of their infection, there are times of asymptomatic viral shedding when HSV becomes active without symptoms and can be transmitted.

While there are vaccines in development to prevent herpes (such as the vaccine used in the Herpevac Trial for Women), currently the only 100% effective method of preventing genital herpes infection is to abstain from any form of genital-to-genital contact or oral-to-genital contact. However, given that most adults will have a sexual relationship at some point in their lives, it is important to understand how herpes is transmitted along with other ways to reduce the risk of contracting the virus.
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How Can One Reduce The Risk Of Getting Herpes?
In a sexual relationship, there are ways to reduce the risk of contracting herpes:

* Talk. Talk with a partner about herpes, other sexually transmitted diseases and birth control before engaging in sexual contact. Finding out if a partner has herpes or other STDs can help both individuals decide which precautions are right for them.

* Avoid skin-to-skin contact with herpes lesions. If your partner has a cold sore or a genital lesion, avoid kissing, oral-genital, or genital-to-genital contact. Symptoms of prodrome and outbreaks indicate viral activity and pose the greatest risk of passing the virus to another person.

* Use condoms between outbreaks as a guard against unrecognized herpes. Consistent and correct use of condoms effectively reduces (but does not eliminate) the risk of contracting herpes. Condoms are not recommended as protection during herpes outbreaks because a lesion may be in a place the condom doesn't cover. But they decrease the risk of genital herpes during asymptomatic shedding, especially if used consistently.

* Antiviral medication may help. For individuals with genital herpes, taking a 500mg dose of valacyclovir each day has been shown to decrease the risk of a partner developing genital herpes symptoms by 77% and the overall risk of HSV infection by 50%.

What About Pregnancy?
Transmission of herpes to newborns is rare and most mothers with a history of genital herpes have vaginal deliveries and healthy babies. However, an infant who gets herpes can become very ill or die. If a woman becomes pregnant, it is important to tell her health care provider if either she or her partner has genital herpes.

If a woman has no history of herpes but has a sexual partner who does, it is especially important that she avoid contracting herpes during pregnancy. A first infection during late pregnancy is the most serious risk to the baby.

What About Testing For Herpes?
There are several tests for herpes. If signs and symptoms are present, a health care provider can look at the area, take a sample (culture) from the symptomatic area, and test to see if the herpes virus is present. From this culture test, a second test can be run to tell whether the virus present is HSV-1 or HSV-2. A culture test will not work if the lesions have healed, and might not work if they're more than a few days old.

Blood tests are also available to test to see if a person has herpes. "Type-specific blood tests" can accurately determine if a person has HSV-1 and/or HSV-2 by looking for an immune response (antibodies) to the virus. Some older blood tests for herpes are not "type-specific" and can give false results. Therefore, if a blood test is performed, it is important to ensure that it can accurately identify HSV antibodies.

The tests used in the Herpevac Trial for Women fall within this type-specific category.

What Is The Meaning Of A 'Positive' Herpes Blood Test?
Even the type-specific blood tests, such as the ones used in the Herpevac Trial for Women, have some limitations. The antibodies they detect indicate long-term HSV infection, but these tests alone cannot tell for certain whether the infection is oral or genital.

If someone tests positive for HSV-1 or HSV-2...

* A positive HSV-1 result most likely indicates an oral infection, though HSV-1 can also cause genital infection.

* A positive HSV-2 test result strongly indicates genital herpes. It is rare for oral herpes to be caused by HSV-2.

* It is also possible to test positive for both HSV-1 and HSV-2. Testing positive for both simply means that a person has both oral and genital herpes, which is not uncommon.

What Is The Meaning Of A 'Negative' Herpes Blood Test?
Testing negative for HSV-1 and HSV-2 indicates that the individual has not contracted a herpes infection. Females who test negative for both types of HSV may be eligible to participate in the Herpevac Trial for Women.