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HIV/AIDS: Epidemiology,
Prevention and Control
1st YEAR
Dr. NOUREEN SABA WAHEED
Community Health Sciences
Shifa College of Medicine
Introduction
• Human
Immunodeficiency Virus
• Acquired immune
deficiency syndrome
• Progressively reduces the
effectiveness of the
immune system and
leaves individuals
susceptible to
opportunistic infections
and tumors
HIV Pandemic
 AIDS is now a pandemic
 As of 2009, it is estimated that there are 33.3 million
people worldwide living with HIV/AIDS
 2.6 million new HIV infections/year
 1.8 million annual deaths due to AIDS
In 2007, UNAIDS estimated:
 33.2 million people worldwide had AIDS
 AIDS killed 2.1 million people in the, including 330,000
children
 76% of those deaths occurred in sub-Saharan Africa
UNAIDS 2009 report
 worldwide 60 million people have been infected
 25 million deaths
 14 million orphaned children in southern Africa alone
since the epidemic began
History
 1950s: Blood samples from Africa
•
Genetic research indicates that
HIV originated in west-central
Africa during the late nineteenth or
early twentieth century. AIDS was
first recognized by the U.S.
Centers for Disease Control and
Prevention in 1981 and its cause,
HIV, identified in the early 1980s
•
Gay-related immune deficiency
(GRID) (sometimes informally
called the gay plague or GRIDS)
was the 1982 name first proposed
to describe what is now known as
AIDS, after public health scientists
noticed clusters of Kaposi's
sarcoma and Pneumocystis
pneumonia among gay males in
Southern California and New York
City
have HIV antibodies.
 1976: First known AIDS patient died.
 1980: First human retrovirus
isolated (HTLV-1).
 1981: First reports of “Acquired
Immuno-deficiency Syndrome” in
Los Angeles.
 1983: Virus first isolated in France
(LAV).
 1984: Virus isolated in the U.S.
(called HTLV-III and AIDS-Related
Virus, ARV).
 1985: Development and
implementation of antibody test to
screen blood donors.
History (cont…)
 1986: Consensus name Human Immunodeficiency Virus
(HIV-1).

Related virus (HIV-2) identified.
 1992: AIDS becomes the leading cause of death among
adults ages 25-44 in the U.S.
 1997: Mortality rates of AIDS starts to decline due to the
introduction of awareness and new drug cocktails.
 2001: World Health Organization predicts up to 40 million
infected individuals. More than 22 million have already died
Agent factors
• AIDS is the ultimate clinical consequence of infection
with HIV
• HIV is a retrovirus that primarily infects vital organs of
the human immune system such as CD4+ T cells (a
subset of T cells), macrophages and dendritic cells
• It directly and indirectly destroys CD4+ T cells
• Once HIV has killed so many CD4+ T cells that there are
fewer than 200 of these cells per micro liter (µL) of blood,
cellular immunity is lost
• Acute HIV infection -> clinical latent HIV infection ->
Early symptomatic HIV infection ->AIDS
• AIDS is identified either on the basis of the amount of
CD4+ T cells remaining in the blood, and/or the
presence of certain infections
• Reservoir Cases and Carriers
HIV-Infected T-Cell
HIV
Virus
T-Cell
HIV Infected
T-Cell
New HIV
Virus
10
Source - HIV in Body Fluids
Blood
18,000
Semen
11,000
Vaginal
Fluid
7,000
Amniotic
Fluid
4,000
Saliva
1
Average number of HIV particles in 1 ml of these body fluids
11
Host factors
Modes of spread
Transmission of AIDS (Worldwide)
• Sexual contact with infected individual: All forms of sexual
intercourse (homosexual and heterosexual). 75% of transmission.
• Sharing of unsterilized needles by intravenous drug users and
unsafe medical practices: 5-10% of transmission.
• Transfusions and Blood Products: Hemophiliac population was
decimated in 1980s. Risk is low today. 3-5% of transmission.
• Mother to Infant (Perinatal): 25% of children become infected in
utero, during delivery, or by breast-feeding (with AZT only 3%). 510% of transmission.
14
Stages of Infection
Window Period
• This is the period of time after becoming
infected when an HIV test is Positive
• 90 percent of cases test positive within
three months of exposure
• 10 percent of cases test positive within
three to six months of exposure
Before and after IV drug abuse
leading to HIV infection
HIV Testing
EIA/ELISA
Test
Positive
Negative
No HIV Exposure
Low Risk
Repeat
Positive
HIV Exposure
High Risk
Negative
Repeat ELISA
Every 3 months
for 1 year
Repeat every
6 months for continued
High risk behavior
End Testing
Negative
Positive
Indeterminate
Repeat at
3 weeks
Run IFA
Confirmation
Negative
Repeat at
2-4 months
Positive
HIV
+
20
Blood Detection Tests
• Enzyme-Linked Immunosorbent Assay/Enzyme
Immunoassay (ELISA/EIA)
• Radio Immunoprecipitation Assay/Indirect
Fluorescent Antibody Assay (RIP/IFA)
• Polymerase Chain Reaction (PCR)
• Western Blot Confirmatory test
AIDS Associated Disease Categories
1. Gastrointestinal: Cause most of illness and
death of late AIDS.
Symptoms:
• Diarrhea
• Wasting (extreme weight
loss)
• Abdominal pain
• Infections of the mouth and
esophagus.
• Pathogens: Candida
albicans, cytomegalovirus,
Microsporidia, and
Cryptosporidia.
AIDS Associated Disease Categories
2. Respiratory
70% of AIDS patients develop
serious respiratory
problems.
Partial list of respiratory
problems associated
with AIDS:
• Bronchitis
• Pneumonia
• Tuberculosis
• Lung cancer
• Sinusitis
• Pneumonitis
AIDS Associated Disease
Categories
3. Neurological:
Opportunistic diseases and
tumors of central nervous
system.
Symptoms many include:
Headaches, peripheral
nerve problems, and AIDS
dementia complex
(Memory loss, motor
problems, difficulty
concentration, and
paralysis)
AIDS Associated Disease
Categories
4. Skin Disorders: 90% of AIDS patients
develop skin or mucous membrane
disorders.
•
Kaposi’s sarcoma
–
1/3 male AIDS patients develop KS
–
Most common type of cancer in AIDS
patients
•
Herpes zoster (shingles)
•
Herpes simplex
•
Thrush
•
Invasive cervical carcinoma
5. Eye Infections: 50-75% patients
develop eye conditions.
•
CMV retinitis
•
Conjunctivitis
•
Dry eye syndrome
Why is an HIV vaccine so difficult?
Natural infection does not clear virus –
immunity?
1. Rapid genetic evolution – moving target
2. Super-infections – leads to recombinant viruses
3. HIV-1 integrates - human chromosomes (genes)
– long lived memory T cell cells-reservoir
4. Virus coat - gp120(Env) – evades detection
– conceals receptor for binding
– Interferes with host attack on virus - MHC
•
Narrow window for efficacy - early infection
HIV Risk Reduction
• Avoid unprotected sexual contact
• Use barriers such as condoms and dental
dams
• Limit multiple partners by maintaining a longterm relationship with one person
• Talk to your partner about being tested before
you begin a sexual relationship
HIV Risk Reduction
• Avoid drug and alcohol use to maintain
good judgment
• Don’t share needles used by others for:
Drugs
Tattoos
Body piercing
• Avoid exposure to blood products
Primary prevention
• High risk
• Population / mass
strategy
• Health promotion
• Specific protection
Secondary prevention
• Early diagnosis
• Prompt treatment
Tertiary prevention
• Rehabilitation
• Disability limitation
Chronic Herpes Simplex infection with lesions on tongue and lips.
Source: Atlas of Clinical Oral Pathology, 1999.
Department of Community
Medicine IIMC Rawalpindi
32
Extensive tumor lesions of Kaposis’s sarcoma in AIDS patient.
Source:
1997
DepartmentAIDS,
of Community
Medicine IIMC Rawalpindi
33
Opportunistic Oral Yeast Infection by Candida albicans in an AIDS Patient
Source: Atlas of Clinical Oral Pathology, 1999
Department of Community
Medicine IIMC Rawalpindi
34
African AIDS patient with slim disease
Source: Tropical Medicine and Parasitiology, 1997
Department of Community
Medicine IIMC Rawalpindi
35
Thank you
• 'Umar bin Al-Khattab left for Sham, and when he
reached a placed called Sargh, he came to
know that there was an outbreak of an epidemic
(of plague) in Sham. Then 'AbdurRahman bin
'Auf told him that Allah's Apostle said, "If you
hear the news of an outbreak of an epidemic
(plague) in a certain place, do not enter that
place: and if the epidemic falls in a place while
you are present in it, do not leave that place to
escape from the epidemic." So 'Umar returned
from Sargh.
Sahih Al Bukhari