HOW DOES HIV/AIDS SPREAD?
HIV infection spreads through 3 main routes:
- Direct - sexual intercourse or deep kissing. Oral or anal sex also
leads to transmission of virus from one partner to the other
- Indirect body fluids of the infected person like blood, vomit,
excreta etc and infected syringes. HIV is present in all body fluids of an infected
person. It is however more in number in blood, semen and vaginal fluids.
- Vertical mother to child transmission during pregnancy or
More than 75% people are estimated to get it through sexual
The probability of getting the infection, with one encounter, is not
the same by all routes.
WHAT THEN DECIDES THE FATE OF TRANSMISSION?
Four mains conditions must be fulfilled if HIV is to be transmitted
through any one of the three routes mentioned above. These includes:
- HIV must be present in the body fluids, especially the semen, vaginal fluids, blood or
- HIV must live during the period it is out of the body. It can live for a long time in
blood stored at cold temperatures for transfusion but lives for a short time in all other
situations as the body fluids dry very easily. HIV cannot survive in dried body fluids.
- There must be convenient portal for entry. The normal skin forms a very effective
barrier and HIV will find it difficult to enter through intact skin. The virus can easily
enter the body from wherever there is damage to the skin or the skin is more delicate
(such as vagina
- The number of viruses in the body fluids must be adequate to infect others after it is
transferred to contact with body fluids. If the number of viruses that enter another
person is less, then the infection may not occur.
The most common (75%) route of the spread of HIV infection is through
unprotected sex (without condom) between two people, one of whom already has HIV
infection. Unprotected vaginal sex, is a more common source of infection in India as
compared to unprotected anal sex. HIV is present in the sperms as well as the seminal
Even one episode of unprotected sex with an infected partner can
transmit HIV. Multiple such episodes increase the risk of infection.
Women are at greater risk of developing HIV infection through
unprotected sex. This means that the risk of transmission of HIV from man to woman is
higher than that from woman to man. There are several reasons why women are at greater
- The semen from the infected male sexual partner remains in the womans vagina
for a longer time. Longer contact between infected semen and delicate wall of the vagina
increases the risk of HIV infection.
- The surface area of the vagina is very large
compared to the urethra in men. Larger surface area
provides greater opportunity for the virus to enter the body.
- A large number of women who have sexually transmitted infections of their
reproductive tract may not have any symptoms at all. In the absence of any symptoms, they
will not know they have the infections and will therefore not take appropriate treatment.
These STDs allow greater opportunity for the HIV
to enter the body and cause infection.