|
According to WHO and
UNAIDS…
-38.6 Million Living
With AIDS
Picture:
African man with AIDS
Source
HIV History
-Thought to have a
primate origin, although there is no
consensus on how it jumped to humans
Earliest Cases of
Infection
Picture Source
1959 - Plasma sample
from an adult male (Democratic Republic of
Congo)
1969 - Tissue sample
from a 15 year old African-American in St.
Louis
1976 - Tissue sample
from a Norwegian sailor
1981 - CDC officially
recognized the epidemic; it was originally
named GRID (gay-related immunodeficiency)
1982 – CDC renamed the
disease from GRID to AIDS (AutoImmunoDeficiency
Syndrome) after it was realized that half of
the people with the disease were not
homosexual
HIV Infection
-HIV is a retrovirus.
This means that the virus has an enzyme
called reverse transcriptase that can make
DNA from its RNA; then it can use another
enzyme (integrase) to integrate the DNA into
the host’s genome.
Picture Source
-There are two strains
of HIV: 1 and 2. HIV 1 is responsible for
the majority of cases, HIV 2 is largely
confined to West Africa
-HIV attacks the human
immune system. CD4 cells are necessary for
proper immune function; they activate all
other immune system cells. HIV can
indirectly and directly kills CD4 cells.
-Threshold for AIDS
classification is when the individual has
fewer than 200 CD4+ T cells
HIV Life Cycle
 Cycle
Source
In a nutshell…
-HIV infects CD4 helper
T cells
-HIV material enters
cell
-Copies RNA to DNA
-Integrates into the
host genome
-Under certain
conditions, the genes are transcribed into
viral RNA
-Some viral RNA
incorporated into new virus particles
-Virus particles are
released from the cell
There are three ways
to diagnose HIV:
1) WHO Disease
Staging System: HIV-1 Infection and Disease
(1990)
-There are four stages
in this system.
Stage I – asymptomatic;
not categorized as AIDS
Stage II – minor
symptoms such as recurrent upper respiratory
infections
Stage III – more severe
symptoms such as unexplained chronic
diarrhea, severe bacterial infections,
tuberculosis
Stage IV – indicators
of AIDS such as fungal infections, Kaposi’s
Sarcoma, and toxoplasmosis of the brain
Picture:
Kaposi's Sarcoma
Source
2) CDC
Classification System
-Expanded the
classification of AIDS in 1993 to include
having a T cell count below 200 per
microliter of blood.
3) HIV Tests
ELISA and Western blot
assay
-ELISA can sometimes
give false positives
-Detects HIV antibodies
-It can take 6-12
months to test positive
-Some commercially
available tests that aren’t specifically
approved for diagnosis
Epidemiology
Image Source
<<Previous Page |
HIV Symptoms and
Complications
3 stages of HIV
1) Primary HIV
infection:
-HIV replicates rapidly
-Flu-like symptoms
-One to two weeks
2) Asymptomatic
-Lasts around 10 years
-Virus continues to replicate
-Decrease in CD4 count (from
1000 cells/microliter of blood in uninfected adults)
3) AIDS
Image:
X-ray of an individual
with Pneumocystis jiroveci pneumonia
Source
-Opportunistic infections begin
to set in after CD4 count has dropped below 200
Pulmonary: Tuberculosis,
Pneumocystis jiroveci pneumonia
Gastro-intestinal: inflammation
of linings due to fungus/virus/mycobacteria,
parasitic infections
Neurological: toxoplasmosis,
progressive multifocal leukoencephalopathy, AIDS
dementia complex, cryptococcal meningitis
HIV-associated malignancies:
Kaposi’s sarcoma, Epstein-Barr virus, human
papilloma virus, cytomegalovirus
Image:
Toxoplasmosis in brain
Source
Survival
With treatment ~ 5 years
Without treatment ~ 9 months
HIV Transmission
Picture Source
-3 main transmission routes
1) Sexual contact – majority of
new cases
2) Exposure to infected body
fluids/tissues (can occur when sharing syringes or
needles, or during blood transfusions)
3) Mother to fetus during
childbirth and via breastmilk
HIV Prevention
-ABC Approach: Abstinence,
Being faithful to your partner, Condom use
Picture Source
-CNN Approach: Condom use,
Needles (use clean ones), Negotiating skills
(between partners)
-Don’t share needles or
syringes
-Sterilize needles
-Wear latex gloves
Mother to Child Prevention
Picture:
Administration of ART
drugs to a newborn
Source
-Administer anti-retroviral
drugs after birth (lowers transmission risk from 25%
to 1%)
-C-section delivery
-Formula feeding
HIV Treatment
NO VACCINE OR CURE!
Only preventative methods and
antiretroviral treatment:
-Post-exposure prophylaxis
(PEP)
Picture Source
-Highly active antiretroviral
therapy (HAART)
---- including nucleoside
analogue reverse transcriptase inhibitors (NARTIs)
and non- nucleoside reverse transcriptase inhibitors
(NNRTIs)
Next Page>> |
