Few diseases generate so many myths and misunderstandings as HIV. Nearly twenty years into the global pandemic, some people are still confused about how HIV is transmitted. Read on to learn what you need to know to protect yourself.

Who Has HIV Already, and Who is Contracting It Now? At least 750,000 Americans have contracted the human immunodeficiency virus. Half of these people are homosexual males, a sharp contrast to the worldwide distribution of HIV, in which the overwhelming majority of infections have occurred via heterosexual transmission. Due to the adoption of safe sex practices, however, the rate of new HIV infection among gay males is actually decreasing. Because of the perception of HIV as a "gay" disease, heterosexuals have not taken the warnings about HIV as seriously. As a result, the percent increase in new cases through heterosexual transmission in the United States exceeds the percent increase of new cases in gay males.

How Is HIV Transmitted? Sexual transmission is the most frequent mode of infection in the United States, while new cases among intravenous drug users and their sexual partners are increasing rapidly. HIV exists at high levels in a variety of bodily fluids, in particular semen, vaginal secretions, and blood. Thus, extensive contact with these fluids imparts a risk of transmission. HIV is actually not a very resilient virus; it does not survive well outside of the body. For example, transmission will not occur through intact, healthy skin, nor can the virus be transmitted by handling inanimate objects that someone who is HIV positive handled before you (for example, casual contact with a doorknob, toilet seat, phone, etc.). HIV cannot be transmitted via a handshake.

While HIV transmission does not occur through intact, healthy skin, it does occur through mucous membranes, thin layers of moist tissue that line the vagina, the inside of the mouth, and the esophagus, stomach, and rectum (i.e. the gastrointestinal tract), among other organs. HIV can also be transmitted through diseased skin or breaks in the skin, such as through genital ulcers caused by sexually transmitted diseases.

Anoreceptive intercourse (aka "catchers" as opposed to "pitchers"), whether male to male or male to female, carries the highest risk of sexual transmission of the virus. Vaginal intercourse also carries a high risk and is becoming a more common mode of transmission in the United States. The rumor that you cannot get HIV from oral sex has persisted for years. Multiple cases of transmission have occurred through oral sex, through contact with male or female genitalia. Any act in which semen, vaginal secretions, or blood comes into direct contact with the inside of the mouth and esophagus, the inside of the vagina, or the inside of the anus, carries a real risk of transmission.

For several reasons, people who have other sexually transmitted diseases (STDs), such as herpes, syphilis, or gonorrhea, are at a much greater risk of transmitting HIV. First, patients with other STDs have by definition been practicing unsafe sex, and are therefore much more likely to have been infected by HIV. Second, transmission of HIV is much more frequent (perhaps as much as 10 to 100 times more frequent) if genital skin is broken down by ulcerations or inflammation caused by other STDs.

While HIV transmission is known to occur via contact with blood, semen, or vaginal secretions, other bodily fluids, such as saliva, urine, and tears, have never been shown to be capable of transmitting the virus. Although HIV can be found at low levels in the saliva of some patients with the infection, there appear to be inhibitors of the virus in saliva, and therefore the risk of transmission is estimated to be exceedingly small. There has never been a confirmed case of HIV transmission via a kiss.

How Can I Protect Myself? This one is easy to answer. Abstaining from both sex and intravenous drugs is by far the most effective way to protect yourself from contracting HIV.

If you're not going to practice abstinence, use condoms if you are sexually active. Don't risk your life and the life of your sexual partner because you were too "cool" to take the time to put on a condom. A birth control pill can protect you from getting pregnant, but won't do a thing to keep you safe from STDs and HIV. HIV infection is unusual among lethal diseases in that you have the power to keep yourself from getting it. If you are going to have sex, use a barrier protection.