I could not find all these information on E2, so I'll fill the hole. Note that this node deals with HIV transmission (AIDS itself appears after you have been infected.)
The important thing to know is that HIV is transmitted through
some human body secretions generated by mucous membranes, but not
all human body secretions. This is the list of the secretions that may
transmit AIDS, and the situations in which you may be in contact with
them.
- Semen, vaginal or anal secretions. Vaginal or anal sexual
intercourse is one the most common ways to be infected, as well as
oral sex at least for the one who is in contact with the other
person's sex. Female-to-female transmission is rare. Of course, the
risk almost completely disappears using latex condoms.
- Blood. This may typically happen when sharing needles or
syringes with an infected person, whether these needles are used for
drugs, steroids, tattoo, etc. It also used to happen during
blood transfusions before 1985 (depending on your country), but
blood transfusions and donations should be safe nowadays since blood
is tested and the needles are used only once. The situation may be
different in some countries though.
- Pregnancy. A mother infected with HIV may pass the virus to
her baby, with a probability of 1/4.
- Milk. In some case, breastfeeding may transmit the HIV to the baby
(or to anyone who is suckling...)
- Saliva. This is not sure. While a simple (mouth closed) kiss
will not transmit HIV, safety of long, deep kisses (French kiss) is
not completely established. However there is no known case of HIV
transmission through kissing.
Therefore, the following situations will not
infect you:
- using clothes, phones, toilet seats that were used
by an infected person.
- having everyday contact with an infected person, including kissing
her/him on the cheeks or on the (closed) mouth. Sweat and tears do
not transmit AIDS.
- Being bitten by a mosquito. Insects cannot transmit AIDS.
The information was taken on the Journal of the American
Medical Association web site:
http://www.ama-assn.org/special/hiv/support/prvntgd/how.htm and
reorganised.