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HIV and T cells
-HIV infects primarily vital cells in the human immune system such as helper T cells (to be specific, CD4+ T cells), macrophages, and dendritic cells.
- HIV infection leads to low levels of CD4+ T cells through three main mechanisms:
-First, direct viral killing of infected cells; second, increased rates of apoptosis in infected cells; and third, killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells.
-When CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections.
Retrovirus - 'reverse transcriptase
Two primary strains:
HIV-1: found throughout the world
HIV-2: found primarily in West Africa
Both strains have several subtypes
Mode of Transmission
shared needles or equipment
pregnancy, delivery and breastfeeding
CD4 as diagnosis
Healthy person has 800-1200 CD4 cells/mm3
CD4 below 200/mm3 produces vulnerability to opportunistic infections and cancers
%CD4 also used to diagnose AIDS - count below 14%
-HIV infection / AIDS now worldwide
-1988- AIDS had been reported in 138 countries (WHO) and 5 and 10 million individuals were infected with the virus
2008 - prevalence estimated at 33.4 million
-Estimated 20% of infected people in US do not know that they are infected! (Knox, 2008)
-3 epidemiological patterns of transmission:
----Pattern 1 - predominantly among homosexual men, drug users
-----Pattern 2 - heterosexual sex, prostitution, blood transfusions, unsterile injections, preinatally
------Pattern 3 - infection from infected individuals from Patterns 1 and 2 or importation of blood
Global estimates for adults and children, 2008
-People living with HIV 33.4 million [31.1 - 35.8 million]
-New HIV infections in 2008 2.7 million [ 2.4 - 3.0 million]
-Deaths due to AIDS in 2008 2.0 million [1.7 - 2.4 million]
Over 7400 new HIV infections a day in 2008
More than 97% are in low- and middle-income countries
About 1200 are in children under 15 years of age
About 6200 are in adults aged 15 years and older,
------------almost 48% are among women
------------about 40% are among young people (15-24)
Until end of 1997 - over 36,000 infections and 16,000 AIDS cases
By 2007 - over 59,000 infections and 20,000 AIDS cases
Infection is almost 5 times greater in males: 49,000 versus 10,000
Nucleoside reverse transcriptase (RT) inhibitors:
interrupts an early stage of the virus making copies of itself
time between HIV and AIDS
More than 10 years for the disease to progress from HIV infection to AIDS
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