How Do You Get Herpes? Causes and Risk Factors

Herpes infections are caused by herpes simplex virus (HSV) types 1 and 2. These contagious viruses are spread through skin-to-skin contact with a person who is having a herpes outbreak.

You get herpes by touching a herpes sore or the skin, lips, genital fluids, or saliva of a person with an oral or genital herpes infection. Herpes can be spread even when there are no visible blisters or sores.

This article discusses how herpes is spread. It also explains who is at high risk for herpes and how you can protect yourself.

Common Causes

You can get herpes when one of the herpes simplex viruses enters through your skin and travels to the nerves. When this virus becomes active, it can cause skin sores.

The herpes viruses spread when they come in contact with broken skin or with the mouth, vagina, penis, or anus.

HSV1 causes cold sores. Herpes type 1 is spread by kissing, touching, and oral sex.

HSV2 causes blisters on the skin around the vagina, vulva, cervix, penis, scrotum (balls), butt, anus, upper thighs, or mouth. You get herpes type 2 from sexual contact, including:

• Intercourse
• Oral sex
• Anal sex
• Hand-to-genitals contact
• Contact with semen or vaginal fluids of a person who has herpes
• Sharing sex toys with someone who has herpes

Unfortunately, there is no way to detect asymptomatic shedding, so you have to consider herpes contagious all the time, even in the absence of symptoms.

People can reinfect themselves by touching a sore and then scratching or rubbing another area of skin on their own body.

Women who have vaginal HSV-2 infections can also transmit the virus to their babies during vaginal delivery. This type of transmission is more common if the mother has newly acquired the infection.

How Herpes Outbreaks Occur

Once it enters a human cell, the HSV virus penetrates the cell's nucleus and begins the process of replication. Even though cells may be infected, you probably will not experience any symptoms at this stage.

During the initial infection, the virus is transported through nerve cells to nerve-branching points, known as ganglia. There, the virus will stay in an inactive, dormant state, neither replicating nor presenting any signs that it's even there.

On occasion, the dormant virus may suddenly reactivate, starting the replication process anew. When this happens, the virus will travel back through the nerve to the surface of the skin. With this, many of the infected skin cells are killed, causing blisters to form. The eruption of these blisters creates the characteristic ulcers that are recognized as cold sores or genital herpes.

What Triggers Outbreaks?

Certain triggers can cause the herpes virus to reactivate. This is known as a recurrence and can happen even if you have a healthy immune system.

There are several known triggers that can stimulate recurrence, including:

• Physical stress, such as an infection, an illness, or an injury
• Persistent emotional stress or anxiety for greater than one week
• Exposure to ultraviolet light (UV light, such as from the sun), excessive heat, or cold
• Hormonal changes, such as during menstruation
• Fatigue

Health Risk Factors

A number of health factors can predispose you to a more severe or longer-lasting HSV infection if you already have HSV-1 or HSV-2. However, these risk factors do not make you more likely to acquire the infection. They are:

• Immunosuppression: If your immune system is deficient for any reason, you are at a greater risk of having a more serious or persistent HSV infection and more frequent reactivations. Your immune system can be suppressed for several reasons, including an autoimmune condition, human immunodeficiency virus (HIV), immunoglobulin A (IgA) disease, an illness such as cancer of the bone marrow, chemotherapy treatment, or organ transplantation.
• Immunosuppressive medication use: You can have a worse HSV-1 or HSV-2 infection or a reactivation if you are on an immunosuppressive medication such as a steroid or chemotherapy. This should no longer be the case once you stop taking the medication and your immune system function returns to normal.
• HIV: HIV infection specifically causes decreased immunity to viruses, and herpes virus infections may be more severe if you have an HIV infection. 
• IgA deficiency: While any immune deficiency can predispose you to recurrent sores or to a more severe bout of HSV infection, IgA deficiency is the immune deficiency most often associated with HSV. IgA is an immune protein that specifically protects against infections of the mucous membranes, which are the areas of thin skin that are protected by a fluid-like mucus, such as the mouth and vagina. 

Lifestyle Risk Factors

Herpes is a particularly common virus, and there is an especially high risk of exposure associated with certain activities, including:

• Unprotected sex: HSV-2 is most often transmitted from one person to another through sex, including oral sex. HSV-1 can also be transmitted through sexual activity, although it is not as common. Having multiple sexual partners and having unprotected sex with partners who could be infected raise your risk. 
• Kissing: Kissing or other mouth contact is one of the most common ways of transmission of HSV-1. 
• Sharing items: The HSV-1 virus can be transmitted by sharing items such as cups, toothbrushes, and even recently exposed towels. Using someone else's lipstick, lip gloss, or lip balm is particularly problematic, as these items are inherently moist, which allows the virus to stick around easily.
• Prolonged skin-to-skin contact: Herpes gladiatorum, a type of infection caused by HSV-1, is characterized by sores on the face, head, and neck. This type of herpes infection is most often noted among wrestlers.