Hiv and Aids
HIV AND AIDS
Definition
AIDS or acquired immunodeficiency syndrome - was originally defined empirically by the Centers for Disease Control and Prevention(CDC) as “the presence of a reliably diagnosed disease that is at least moderately indicative of an underlying defect in cell-mediated immunity.” Following the recognition of the causative virus, HIV, and the development of the sensitive and specific tests for HIV infection, the definition of AIDS has undergone substantial revision. The current surveillance definition categorizes HIV-infected persons on the basis of clinical conditions associated with HIV infection and CD4+T lymphocyte counts.
Etiology
AIDS is caused by the infection with the human retroviruses HIV-1 or HIV-2. HIV-1 is the most common cause worldwide; HIV-2 has about 405 sequence homology with HIV-1, is more closely related to simian immunodeficiency viruses, and has been identified predominantly in western Africa. HIV-2 infection has now, however, been reported in europe, south america, canada, and the united states. These viruses are passed through sexual contact; through contact with blood, blood products, or contaminated intravenous needles; intrapartum or perinatally from mother to infant; or via breast milk. Ther e is no evidence that the virus can be passed through casual or family contact or by insect bites such as mosquitoes. There is a definite, though small, occupational risk of infection for health care workers and laboratory personnel who work with HIV-infected specimens. The risk of transmission of HIV from an infected health care worker to his or her patients throug invasive procedures is extremely low.
Epidemiology
By january 1, 1997, a cumulative total of approximately 570,000 cases of AIDS has been reported in the United States; approximately 60% of those had died. It has been estimated that there are between 630,000 and 897,000 HIV-infected people in the U.S. Major risk groups continue to be men who have had sex with
Definition
AIDS or acquired immunodeficiency syndrome - was originally defined empirically by the Centers for Disease Control and Prevention(CDC) as “the presence of a reliably diagnosed disease that is at least moderately indicative of an underlying defect in cell-mediated immunity.” Following the recognition of the causative virus, HIV, and the development of the sensitive and specific tests for HIV infection, the definition of AIDS has undergone substantial revision. The current surveillance definition categorizes HIV-infected persons on the basis of clinical conditions associated with HIV infection and CD4+T lymphocyte counts.
Etiology
AIDS is caused by the infection with the human retroviruses HIV-1 or HIV-2. HIV-1 is the most common cause worldwide; HIV-2 has about 405 sequence homology with HIV-1, is more closely related to simian immunodeficiency viruses, and has been identified predominantly in western Africa. HIV-2 infection has now, however, been reported in europe, south america, canada, and the united states. These viruses are passed through sexual contact; through contact with blood, blood products, or contaminated intravenous needles; intrapartum or perinatally from mother to infant; or via breast milk. Ther e is no evidence that the virus can be passed through casual or family contact or by insect bites such as mosquitoes. There is a definite, though small, occupational risk of infection for health care workers and laboratory personnel who work with HIV-infected specimens. The risk of transmission of HIV from an infected health care worker to his or her patients throug invasive procedures is extremely low.
Epidemiology
By january 1, 1997, a cumulative total of approximately 570,000 cases of AIDS has been reported in the United States; approximately 60% of those had died. It has been estimated that there are between 630,000 and 897,000 HIV-infected people in the U.S. Major risk groups continue to be men who have had sex with