Blood transfusion due to possibility of blood or material used is contaminated with HIV,
Pregnancy, because of the possibility of the mother or may be be infected with HIV and transmit it to the fetus during pregnancy, childbirth or later through breastfeeding;
Invasive procedures (entering the body), due to the possibility of instruments (scalpels, tweezers, nail pliers, needles tattoos or acupuncture, razors etc.) used are not sterile or have not been properly sterilized. http://boards.flexonline.com/viewtopic.php?f=3&t=4372
ANTI-HIV TESTING WINDOW IMMUNE
To find out if you are infected or not, the individual must wait, on average, three months after exposure to a hazardous situation, only to undergo the HIV test.
This period is called the "window period" that is, it is the time taken for the body to produce sufficient quantities of antibodies against the virus, as to be detected by blood tests.
In addition, the tests do not directly detect the virus, but antibodies to this virus must be repeated six months after exposure.
There is the normal human body cite pathos viruses (capable of destroying cells) called CD4, which is responsible for alerting the immune system (the body's defense system) that is necessary to defend himself. http://www.weighttogoforum.com/viewtopic.php?f=9&t=650
Without being warned they need to fight the invaders, this system fails in its task, making AIDS patients more vulnerable to one or more infections caused by bacteria, viruses or other parasites.