AIDS

             person contains over one thousand CD4 cells per microliter of blood. HIV .
             slowly diminishes the cells over a period of years, weakening the immune .
             system. When the amount of CD4 cells reduces to two hundred cells, the .
             person becomes vulnerable to about twenty-six infections and cancers.
             HIV is most commonly transmitted during sexual intercourse with an .
             already infected person. During this, the virus has access to the bloodstram, .
             passing through openings in the nucous membrane and through breaks in the .
             skin of the penis. HIV is commonly transmitted between homosexual men in the .
             United States and Canada. The transmission between heterosexual men and .
             women, however, has increased. .
             When individuals using heroin or other injected drugs share needles .
             contaminated with infected blood, direct contact with HIV occurs. In Eastern .
             Europe, the sharing of contaminated needles among drug users is the most .
             common cause of HIV.
             HIV infection may also occur when health professionals stick themselves, .
             accidentally, with HIV infected needles. Exposure of an open cut to infected .
             blood is another result. Since 1985, government regulations have required that .
             all donated blood and body tissues be screened before being used in .
             procedures. Because of this, HIV transmission caused by blood transfusion .
             and organ donations has been reduced in North America. In few nations, only .
             twenty-five percent of blood transfusions are screened.
             HIV may be spread by an infected mother to her baby while the baby is .
             either still in the woman's uterus or during childbirth. HIV can be transmitted .
             through the mother's breast milk during brastfeeding. Mother-to-child .
             transmission is ninety percent of all cases of AIDS in children. In Africa, the .
             number of women infected with HIV is ten times more than other regions. In .
             southern African cities in 1998 up to forty-five percent of pregnant women .
             carried HIV.
             Well documented by scientists are the routes of the transmission.