Human immunodeficiency virus, or HIV, is a chronic and damaging disease ultimately resulting in the terminal condition known as AIDS. The Mayo Clinic reports that an estimated 39 million people worldwide have HIV. Transmission of this virus takes several forms, and understanding the risks for transmission helps to prevent the contraction and spread of the virus.
Conditions For Transmission
The San Francisco AIDS Foundation, or SFAF, explains that there are three conditions that must be present for HIV to spread. Although these conditions may seem to be common sense, misconceptions that certain types of behavior, such as sexual positions, cause the virus have lead to assumptions of risk. The presence of HIV in a person is the first condition. Concentration of HIV in the blood versus body fluids determines transmission risk. SFAF explains that a small concentration of the virus in the blood passing from one person to another can spread the infection. In body fluids however, a larger concentration of the virus must be present for transmission. HIV enters only through contact with open wounds and the mucous membrane of the anus, genitals or mouth and eyes. Infected fluid or blood must make contact to get in to the body.
Sexual Contact
The Centers for Disease Control and Prevention note that HIV is most commonly spread through specific sexual behaviors involving anal or vaginal intercourse. Unprotected sex with an HIV-infected partner allows for direct fluid exchange, which allows the virus to enter the mucous membranes in the area of intercourse. Transmission of the virus from oral sex is possible; however, the risk is minimal compared to that of intercourse. According to the SFAF, saliva contains enzymes that break down the virus, making the oral environment less hospitable for HIV. Documented cases of HIV transmission via oral sex are attributed to exposure to semen in the mouth, however. The Mayo Clinic also notes that the sharing of sexual devices from an infected person to an uninfected partner may also spread the virus. Small tears in the genitals or mouth increase the risk of sexually based transmission of the virus.
Needle Transmission
Transmission through contaminated needles and syringes is possible. The Mayo Clinic notes that sharing needles for drug use with an infected person increases the risk of transmission. In health care workers this kind of transmission is also a risk, not because of purposeful needle sharing but owing to accidental sticks. Prevention from needle transmission involves using sterile needles and not sharing needles. Health care workers can take precautions with protective equipment and careful technique to decrease the risk of accidental transmission.
Additional Risks
In less common situations, HIV can be transmitted through blood transfusions. The SFAF explains that since the 1980s, blood screening methods have improved, reducing the risk of transmission through infected blood. Transmission from mother to child has also decreased as a result of medical testing and technology. The Centers for Disease Control and Prevention state that women who are aware of an existing HIV infection can take preventative measures through prenatal care to reduce the risk of passing the virus to their babies.
