HIV TRANSMISSION

An individual can only become infected with HIV through direct contact with certain body fluids from a person with HIV who has a detectable viral load. A detectable viral load is having more than 200 copies of HIV in a milliliter of blood.

Body fluids known to transmit HIV include:

• Blood
• Semen and preseminal fluid
• Rectal fluids
• Vaginal fluids
• Breast milk

In addition, any body fluid visibly contaminated with blood should be considered capable of transmitting HIV. These fluids may include:

• Cerebrospinal
• Amniotic
• Pleural
• Synovial
• Peritoneal
• Pericardial

For transmission to occur, the virus must enter the bloodstream of an HIV-negative person through a mucous membrane. These are located in the:

• Rectum
• Vagina
• Mouth
• Tip of the penis

The virus can also be transmitted through open cuts or sores or through direct injection (e.g., by a needle or syringe).

Unless blood is visibly present, HIV cannot be transmitted by:

• Saliva
• Sputum
• Sweat
• Tears
• Feces
• Nasal secretions
• Urine
• Vomitus

HIV also cannot be transmitted by:

• Air
• Water
• Donating blood
• Closed-mouth kissing
• Insects
• Pets
• Sharing food or drinks
• Sharing toilets

The main routes of HIV transmission are through:

• Unprotected sexual contact with an infected person
• Sharing needles and syringes with an infected person
• From an infected mother to child during pregnancy, during birth, or after birth while breastfeeding

Additional criteria for HIV transmission to occur include:

• HIV must be present in sufficient transmittable amounts.
• HIV must be able to enter the bloodstream of the next person.

(HIV.gov, 2022a; St. Maarten AIDS Foundation, 2023)

Sexual Contact

HIV transmission rates vary by the type of sexual contact; however, men who have sex with men (MSM) are disproportionately at higher risk for HIV infection. The chances of contracting HIV are highest among those who have receptive anal sex (about 1%). HIV probability is lower for those having insertive anal sex, followed by receptive and insertive vaginal sex. With all three types, the odds of contracting HIV after one exposure are well below 1% (Watson, 2022).

HIV acquisition rates among uncircumcised males are higher than for circumcised males. Circumcision reduces the risk of female-to-male HIV transmission by 50%–60%; however, circumcision does not appear to decrease the risk of HIV transmission to the partner (Cohen, 2022).

Injection Drug Use

Sharing injection needles, syringes, and other paraphernalia with an HIV-infected person is the second riskiest behavior following receptive anal sex, potentially sending HIV (as well as hepatitis B and C viruses and other bloodborne diseases) directly into the user’s bloodstream. About 1 in 10 new HIV diagnoses in the United States is attributed to injection drug use or male-to-male sexual contact and injection drug use (CDC, 2021a).

Blood Transfusion

The chances that donated blood will contain HIV is less than 1 in nearly 2 million. While all blood donations are screened for HIV before they enter the blood pool, all laboratory tests have a “window period” in which very recent HIV infections cannot be detected, and in those most sensitive assays that are used by blood collection agencies, this window may be between 10–16 days. Because of this, a very small number of infected samples still make it through testing (Tufts Medical Center, 2022).

Tattooing, Body Piercing

There are no known cases in the United States of anyone becoming infected with HIV from professional tattooing or body piercing. There is, theoretically, a potential risk, especially during the time period when healing is taking place. It is also possible to become infected by HIV from a reused or improperly sterilized tattoo or piercing needle or other equipment, or from contaminated ink. The risk is very low but increases when the person performing the procedure is not properly trained and licensed (CDC, 2022b).

Mother-to-Child Transmission

Before effective treatment was available, about 25% of pregnant mothers with HIV passed the virus to their babies. Today, if the mother is receiving HIV treatment and has a sustained undetectable viral load through pregnancy and postpartum, the risk of passing HIV to the baby is less than 1%. The risk of HIV transmission while breastfeeding is also less than 1% for women with HIV on antiretroviral therapy with sustained undetectable viral load through pregnancy and postpartum (USDOH, 2021; NIH, 2023).

Other Factors Affecting Transmission Risk

Many other factors, alone or in combination, affect the risk of HIV transmission, including the person’s viral load. The higher someone’s viral load (above 100,000 copies per milliliter of blood), the more likely the person is to transmit HIV (IAPAC, 2021).

Another factor that increases risk of acquiring or transmitting HIV is the presence of other sexually transmitted diseases/infections (CDC, 2023).

Occupational Exposures

From 2000 onward, occupationally acquired HIV infection in the United States has become exceedingly rare, with only one confirmed case (Spach & Kalapila, 2023). Risk of transmission of HIV following inadvertent exposure varies widely depending upon the type of exposure. Risk is increased when the source has a high viral load, the volume is large, and the exposure is deep. Healthcare personnel at highest risk are those who have been inoculated percutaneously with blood from a source patient with HIV who is not on suppressive antiretroviral therapy and/or has a detectable viral load (Zachary, 2023).

OCCUPATIONAL INFECTION CONTROL

The state of Florida requires training in Standard Precautions, which are used to prevent HIV transmission in healthcare settings. Standard Precautions are used with all patients at all times and in all settings. They include:

• Personal protective equipment, including gloves, masks, protective eye wear, and/or face shields
• Hand hygiene using soap and water or waterless, alcohol-based hand rub
• Careful handling and disposal of sharp instruments during and after use
• Use of tags or labels to indicate biohazardous material
• Control of personal activities in the workplace (e.g., eating, drinking)

Additionally, the Occupational Safety and Health Administration (OSHA) standards for bloodborne pathogens (BBP, 29 CFR 1910.1030) and personal protective equipment (PPE, 29 CFR 1910 Subpart I) require employers to protect workers from occupational exposure to infectious agents (OSHA, n.d.).

When occupational exposure to HIV occurs, the U.S. Public Health Service recommends that the status of the exposure source patient be obtained and postexposure prophylaxis antiretroviral medication be started within 72 hours and continued for a four-week duration. Expert consultation is recommended, and close follow-up should be provided, with baseline and follow-up HIV testing (Kuhar et al., 2018).