Exploring HIV Transmission Rates

Exploring HIV Transmission Rates


Awareness of HIV has increased over the last few decades. Yet, it is still a prominent health issue worldwide. According to the World Health Organization (WHO), about 1.2 million people died from HIV-related causes in 2014.

The high rates of death and transmission show that more awareness is needed to help stop the virus from spreading.

To help protect yourself, 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 spread the virus and how antiretroviral drugs are making a difference.

Blood and HIV transmission

The Centers for Disease Control and Prevention (CDC) 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.

HIV is most commonly spread through blood. According to the CDC, direct blood transfusion is the route of exposure that poses the highest risk of infection. If you receive a blood transfusion from a donor with HIV, there is high risk of being infected with the virus.

Since 1985, blood banks have adopted stricter screening measures to identify HIV-infected blood. Now all blood donations are tested for HIV. If they test positive, they’re discarded. But even with these safety measures, there’s still a small risk that HIV-infected blood may be used in transfusions.

HIV can also be spread through needle sharing among people who use illegal drugs. It can also be spread through accidental needlesticks in a healthcare setting. However, these transmission routes pose a lower risk of infection than blood transfusions.

The CDC estimates that 63 out of every 10,000 exposures to infected shared needles will result in transmission. For needlesticks, the number falls to 23 in every 10,000 exposures. The risk of spreading HIV through biting, spitting, or throwing bodily fluids is low.

Sex and HIV transmission

Having sex with a person with HIV increases your risk of contracting the virus. HIV may be transmitted both anally and vaginally during sexual intercourse. According to the CDC, the risk of infection for receptive penile or vaginal sex is 8 per 10,000 exposures. For insertive penile-vaginal sex, the risk of infection 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 spread 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 infections per 10,000 exposures. All forms of oral sex are considered low risk. And sharing sexual aids carries a negligible risk of transmission.

It’s important to always protect yourself during sex. If you’re going to have sexual contact with another person, using condoms is the best way to prevent the spread of HIV and other sexually transmitted infections. Condoms act as barriers against semen and vaginal fluids. Latex condoms provide better protection than other types, such as lambskin condoms. Never use a homemade condom.

Sex with a condom is not 100 percent risk-free. Misuse and breakage can be problems. If you’re sexually active, you and your partner should consider getting HIV tests. This can help you understand your risk of spreading or getting the virus. If your partner has HIV and you don’t, the CDC reports that using condoms may lower your risk of getting the virus by 80 percent,

If your partner has HIV and gets antiretroviral therapy, it can reduce the risk of transmission by up to 96 percent. Combining condoms with antiretroviral therapy can provide even more protection.

Mother to child transmission

Aside from blood and sexual secretions, HIV can also be transmitted during pregnancy or through breast milk. Breastfeeding is especially problematic if you don’t know you have HIV. Mother to child transmissions can also occur at any point during pregnancy, as well as during delivery.

If you get pregnant, your doctor will administer an HIV test. If the test comes back positive, they will prescribe anti-HIV drugs. This will help lower your risk of transmitting HIV to your baby during pregnancy and labor. But even if your baby is not infected at birth, you can still spread the virus through breast milk.

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 (NIH) estimates that 1,760 children were infected with HIV during pregnancy or birth in 1992. That number dropped to 142 total cases by 2005.


Antiretroviral drugs for HIV can lower the risk of transmission through all types of exposure, but shouldn’t be your only strategy. In order to prevent the spread of HIV you should also:

  • avoid sharing needles
  • follow safety precautions when working with needles in a healthcare setting
  • use condoms during vaginal, anal, and oral sex
  • get tested for HIV and ask your sexual partners to do the same
  • ask your doctor about steps to protect your fetus or infant from HIV

If you have HIV, you may be at higher risk of spreading it during the early or late stages of your infection. During these two stages, the virus is typically present at high levels in your blood. However, you can also spread HIV at other stages of infection.

If you think you’ve been exposed to HIV, see your doctor. They can test you for the virus. If you test positive, they can discuss your treatment options and strategies to avoid spreading it. 

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