HIV is a relatively fragile virus that is not spread by casual contact. HIV is not easy to “catch”—it must be acquired. In order for HIV to be transmitted, three conditions must occur:
- There must be an HIV source.
- There must be a sufficient dose of virus.
- There must be access to the bloodstream of another person.
One of the predictors of the infectious level of an HIV-positive person is viral load—how much HIV is present in the bloodstream. Studies show a clear connection between higher viral load in the blood and increased transmissibility of HIV.
HIV is transmitted through:
- Unprotected anal, vaginal, and oral intercourse
- Sharing needles or other injection equipment
- A mother passing the virus to her baby either before or during birth
- An infected woman breastfeeding her infant
- Accidental needlestick injuries, or infected bodily fluid coming into contact with the broken skin or mucous membranes of another person (as with healthcare workers)
- A transfusion prior to 1986 of HIV-infected blood or blood products
In extremely rare cases, HIV can be transmitted by sharing razors or toothbrushes, if infected blood from one person was deposited on the toothbrush or razor and the blood entered the bloodstream of another person.
In settings such as hospital operating rooms, other fluids—cerebrospinal fluid, synovial fluid, pleural fluid, pericardial fluid, amniotic fluid—may be considered infectious if the source is HIV-positive. These fluids are generally not found outside the hospital setting. Therefore, the most common body fluids considered potentially infectious for HIV are blood, semen, vaginal secretions, and breast milk.
HIV transmission may occur during practices such as tattooing, blood-sharing activities such as “blood brother” rituals or any other type of ritualistic ceremonies where blood is exchanged, or when unsterilized equipment contaminated with blood is shared. HIV transmission may also occur in occupational settings.
Many people who become infected with HIV from injecting drug use are already infected with hepatitis C (HCV). Some estimate that 40% of HIV-infected people in the United States are also infected with HCV. People who are co-infected with both viruses and have immune system impairment may progress faster to serious, chronic, or fatal liver damage. Most new HCV infections in the United States are among injection drug users. The majority of hemophiliacs who received blood products contaminated with HIV also are infected with HCV.
Treating HIV in someone with HCV may be complicated because many of the medicines that are used to treat HIV may damage the liver; however, treatment for co-infection is possible in some cases with close physician supervision.
People Unaware of Their Positive Status
People who are infected with HIV come from all races, countries, sexual orientations, genders, and income levels. Globally, most of the people who are infected with HIV have not been tested and are unaware that they are living with the virus. The CDC estimates that, in 2006, 21% of those in the United States who had HIV were unaware that they were living with the virus. This is a decline from the 25% measured in 2003 and is a positive sign because research shows that most individuals who know they are infected with HIV will reduce behaviors that could transmit the virus (CDC, 2010).
It is important to note that the great majority of people with HIV infection do not transmit HIV to others. The CDC estimates that in 2006 there were 5 transmissions per 100 people living with HIV infection. This means that at least 95% of those living with HIV infection did not transmit the virus to others that year. This represents an 89% decline in the estimated rate of transmission since the peak level of new infections in the mid-1980s. It is believed that the decline is due to effective prevention efforts and the availability of improved testing and treatments for HIV (CDC, 2010).
An HIV-infected woman may transmit the virus to her baby during pregnancy, during the birth process, or following pregnancy by breastfeeding. One of the predictors of how infectious the woman will be to her baby is her viral load (how much HIV is present in her bloodstream). Women with new or recent infections or people in the later stages of AIDS tend to have higher viral loads and may be more infectious.
HIV is transmitted from an HIV-infected woman to her baby in about 25% of pregnancies if intervention with antiretroviral medications does not occur. The perinatal transmission rate has dropped dramatically in the United States due to the widespread use of the drug AZT by HIV-infected pregnant women. When a woman’s health is monitored closely and she receives a combination of antiretroviral therapies during pregnancy, the risk of HIV transmission to the newborn drops below 2%.
In some pregnancies, cesarean section (C-section) may be recommended to reduce the risk of transmission from mother to baby. Advice about medications and C-section should be given on an individual basis by a medical provider with experience in treating HIV-positive pregnant women. Most states, including Florida, require pregnant women to be counseled regarding risks of HIV and be offered voluntary HIV testing.