Awareness of HIV has increased over the last few decades. According to the World Health Organization (WHO), about 36.7 million people worldwide lived with HIV as of 2016. Still, thanks to antiretroviral therapy (ART), people with HIV are leading longer, better quality lives. Many of these strides have been made in the United States.

To help reduce the risk of transmission, it’s important to understand how the virus is spread. HIV is only transmitted through bodily fluids, such as:

  • blood
  • vaginal secretions
  • semen
  • breast milk

Learn which type of exposure is most likely to transmit the virus and how antiretroviral drugs are making a difference.

Blood transfusions

There is a high risk of transmitting HIV through blood. According to the Centers for Disease Control and Prevention (CDC), direct blood transfusion is the route of exposure that poses the highest risk of transmission. While uncommon, receiving a blood transfusion from a donor with HIV may increase the risk.

The CDC also discusses HIV transmission risk in terms of how many times the virus is likely to be transmitted per 10,000 exposures. For example, for every 10,000 blood transfusions from a donor with HIV, the virus is likely to be transmitted 9,250 times.

Since 1985, however, blood banks have adopted stricter screening measures to identify blood with HIV. Now all blood donations are carefully tested for HIV. If they test positive, they’re discarded. As a result, the risk of contracting HIV from a blood transfusion is very low.

Sharing needles

HIV can be transmitted through shared needles among people who use injected drugs. It can also be transmitted through accidental needlesticks in a healthcare setting.

The CDC estimates that 63 out of every 10,000 exposures to shared drug injection needles will result in transmission. For needlesticks, the number falls to 23 in every 10,000 exposures. However, needlestick safety has evolved significantly and reduced this form of exposure. Examples include safety needles, needle disposal boxes, and needless injections.

Having sex with a person living with HIV increases the risk of contracting the virus. HIV may be transmitted both anally and vaginally during sexual intercourse. According to the CDC, the risk of transmission for receptive penile-vaginal sex is 8 per 10,000 exposures. For insertive penile-vaginal sex, the risk of transmission lowers to 4 out of 10,000 exposures.

Receptive anal intercourse with a partner who is HIV-positive is the sex act that’s most likely to transmit the virus. For every 10,000 instances of receptive anal intercourse with a partner who has HIV, the virus is likely to be transmitted 138 times.

Insertive anal intercourse poses a lower risk, with 11 transmissions per 10,000 exposures. All forms of oral sex are considered low risk. Biting, spitting, throwing bodily fluids, and sharing sex toys all have such a low risk of transmission that the CDC considers the risk “negligible.”

How to practice safe sex

Using condoms regularly and correctly is the best way to prevent the transmission of HIV and other sexually transmitted infections. Condoms act as barriers against semen and vaginal fluids. Always use latex condoms — never use lambskin or homemade condoms, which offer little to no protection.

Still, even sex with a condom is not 100 percent risk-free. Misuse and breakage can be problems. People who are sexually active should consider getting HIV tests along with other STI testing. This can help each person understand the risk of transmitting or contracting the virus.

If one person has HIV and the other doesn’t, the CDC reports that using condoms alone may lower the risk of contracting the virus by 80 percent.

For people who do not have HIV who have a sexual partner living with HIV, the use of pre-exposure prophylaxis (PrEP) can help reduce the risk of transmission through sex. When used daily along with other preventive measures, PrEP can reduce the risk of transmission by as much as 92 percent, according to the CDC.

Living with HIV and taking antiretroviral therapy can reduce the risk of transmission by up to 96 percent. Combining condoms with antiretroviral therapy can provide even more protection. Possible exposure may also be remedied with post-exposure prophylaxis (PEP) treatment.

According to the WHO, this approach includes a combination of:

  • HIV testing
  • counseling
  • 28-day course of antiretroviral therapy for HIV
  • follow-up care

It’s important to note that antiretroviral therapy as a part of PEP treatment for HIV is most effective when started within 72 hours of exposure to HIV.

Having HIV does not mean a woman can’t have a healthy baby. The key is to work with a doctor to take all the necessary precautions.

Aside from blood and sexual secretions, HIV can also be transmitted during pregnancy or through breast milk while breastfeeding. Mother to child transmissions can also occur at any point during pregnancy, as well as during delivery.

All pregnant women should be screened for HIV. Antiretroviral therapy is strongly recommended for pregnant women with HIV to achieve viral suppression. This will subsequently reduce the risk of transmitting HIV to the baby during pregnancy and labor. Sometimes a caesarean delivery is recommended to reduce transmission during delivery if the infection is not suppressed.

It’s also important to protect the baby after birth. Breastfeeding might not be recommended in some cases, though consistent viral suppression may reduce the transmission of HIV through breast milk. A doctor may also recommend that the baby take antiretroviral therapy for up to six weeks after birth.

Overall, great strides have been made in decreasing HIV transmission between mothers and infants due to improved screening and use of anti-HIV drugs during pregnancy.

In the United States, the National Institutes of Health estimates that 1,760 children contracted HIV during pregnancy or birth in 1992. That number dropped to 142 total cases by 2005. Today, the number has dropped to below 2 percent, according to the U.S. Department of Health and Human Services.

Antiretroviral therapy for HIV can lower the risk of transmission through all types of exposure. The problem is when people don’t know the status of one of their sexual partners, or if they continue to use shared needles when using injected drugs.

To prevent the transmission of HIV:

  • seek PrEP before exposure — this drug must be used every day
  • avoid sharing needles by purchasing clean needles from your pharmacy, if available
  • follow safety precautions when working with needles in a healthcare setting
  • use condoms during vaginal and anal sex
  • avoid oral sex if the HIV status of a partner is unknown
  • get tested for HIV and ask sexual partners to do the same by developing a strategy in advance
  • seek PEP treatment after exposure
  • ask a doctor about the proper steps to protect a fetus or infant from HIV, including testing, ART, and viral suppression

Anyone who thinks they might have contracted HIV needs to get tested immediately. Early treatment can help manage the symptoms, lower the risk of complications, lower the risk of transmitting HIV to a sexual partner, and help people to live a long and healthy life.