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HIV Transmission
HIV Must Be Present
Infection may only occur if one of the persons involved in an exposure situation
is infected with HIV. Some people assume that certain behaviors or exposure
situations can cause HIV disease, even if the virus is not present. This
is not true.
There Needs to Be Enough Virus
The concentration of HIV determines whether infection will occur. In blood,
for example, the virus is very concentrated. A small amount of blood is
enough to infect someone. Also, the concentration of virus in blood or other
fluids can change, in the same person, over time.
HIV Must Get into the Bloodstream
It is not enough to be in contact with an infected fluid for HIV to be transmitted.
Healthy, intact skin does not allow HIV to get into the body. HIV can enter
through an open cut or sore, or through contact with the mucous membranes.
Transmission risk is very high when HIV comes in contact with the more porous
mucous membranes in the genitals, the anus, and the rectum, which are inefficient
barriers to HIV. Transmission is also possible through oral sex because
body fluids can enter the bloodstream through cuts in the mouth.
Paths of Infection
HIV can be transmitted through:
- Unprotected vaginal, anal and oral sex.
- Direct blood contact, which may occur through needle sharing, transfusions,
accidents in health care settings, or certain blood products.
- Mother to baby; before or during birth or through breast milk.
Infectious Fluids
HIV can be transmitted from an infected person to another through:
- Blood
- Semen (including pre-seminal fluid)
- Vaginal secretions
- HIV can also be transmitted through breast milk-expressed through
feeding, in limited circumstances where there is exposure to large quantities.
Non-Infectious Fluids
Saliva—is NOT considered to be infectious. The only
time saliva would pose a risk would be if it had blood present in it.
There are no documented cases of HIV transmission through saliva. There
is a protein in the mouth that attaches itself to the surface of blood
cells and blocks infection by HIV that appears to be present in the mucous
membrane in the mouth at a level sufficient enough to reduce the concentration
of HIV in saliva to non-infectious levels.
Urine and Tears—are NOT considered infectious. While
HIV has been found in urine and tears, it is not concentrated in an amount
sufficient for transmission.
Sweat, Feces, Vomit—are NOT considered infectious.
HIV has never been found in these materials. The only possible risk would
be if there was blood present.
HIV Transmission Routes
HIV can enter the body through open cuts or sores and by directly infecting
cells in the mucous membranes. Transmission can happen in the mouth, the
eyes, vagina, penis (through the urethra), in the anus and rectum. HIV
cannot cross healthy, unbroken skin.
Sexual Transmission
HIV can be transmitted through sexual intercourse, both vaginal and anal.
HIV can easily pass through the mucus membranes in the genitals and the
rectum, or may pass through cuts and sores. HIV can also be transmitted
through oral sex. Conditions such as bleeding gums and poor oral health
increase the risk of transmission and through oral sex.
Non-sexual Transmission
HIV can be transmitted by contact between infectious fluids and bleeding
cuts or open sores in the skin. However, healthy, intact skin does not
allow HIV to enter the body, and provides an excellent barrier against
the virus.
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Sharing Needles—Sharing
syringes [needles, works or fits] to inject medicines, hormones, steroids
or illegal drugs can pass blood directly from one person's blood stream
to another's. It is a very efficient way to transmit HIV and other
blood borne viruses such as Hepatitis B (HBV) and Hepatitis C (HCV).
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Tattoos and Piercing—There
have been NO documented cases of transmission of HIV by piercing or
tattooing. However, there are documented cases of Hepatitis B (HBV)
through these routes. Since Hepatitis B and HIV are transmitted by
the same activities, there may be a possibility of HIV transmission
through tattoos and piercing. |
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Blood Transfusions—Since
March 1985, all blood in the United Stateshas been screened for HIV.
This practice has almost eliminated the risk of getting HIV through
a blood transfusion in the United States. |
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Hemophiliacs—Since March
1985, all blood in the United States has been screened with the HIV
antibody test. This practice has almost eliminated the risk of getting
HIV through a blood transfusion in the United States. |
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Other Blood Products—Besides
whole blood, platelets [red blood cells] have transmitted HIV. Current
blood screening should prevention infection from these products. No
other blood products are suspected of transmitting HIV. |
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Organ Donation—People who
are infected with HIV are encouraged not to donate organs or tissue
for transplant purposes. There were very few cases of organ or tissue
transplant HIV transmission from 1985 until 1994 when new government
guidelines were implemented to reduce the risk of transplant transmission.
These guidelines require blood from donors be tested for various strains
of HIV. Also, the donor medical history must show no evidence of risk
factors or clinical symptoms of HIV infection. |
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Mother to Infant Transmission—It
is possible for a mother who has HIV to pass the virus to her fetus,
by exposure to blood and vaginal fluids during birth, or through breast
milk during feeding. |
Last Updated:
Tuesday, April 3, 2007
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Content Notice: This site contains HIV
prevention messages that may not be appropriate for all audiences. Since
HIV infection is spread primarily though sexual practices or by sharing
needles, prevention messages and programs may address these topics. If
you are not seeking such information or materials, please exit this Web
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