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Module 1
Nepal PMTCT Training
Session 2
HIV introduction and Disease progression

Nov 2010
National Centre for AIDS
and STD Control
Session 2 Objectives
• Explain the difference between HIV and AIDS.
• Understand the differences between HIV-1 and HIV-2
infection.
• Discuss the natural course of HIV infection.
• Present public health strategies to prevent the
transmission of HIV.

Nov 2010
and STD Control
Definition of HIV
• HIV stands for human
immunodeficiency virus,
the virus that causes AIDS.
– H: Human
– I: Immunodeficiency
– V: Virus

Nov 2010
and STD Control
Effects of HIV
• HIV breaks down the body's
defence against infection and
disease—the immune system
• HIV destroys specific white blood
cells (CD4 cells) → weakens the
immune system
• The body cannot fight illness

Nov 2010
and STD Control
Effects of HIV (Continued)
It is chronic manageable condition

Nov 2010
and STD Control
Effects of HIV (Continued)
• As time passes, the immune system is unable to
fight the HIV infection and the person may develop
opportunistic infections (OIs)

Nov 2010
and STD Control
Definition of AIDS
• AIDS stands for Acquired Immunodeficiency Syndrome and
refers to the most advanced stage of HIV infection.
– A:Acquired — (not inherited) to differentiate from a
genetic or inherited condition
– I:Immuno — refers to the immune system
– D:Deficiency — inability to protect against illness
– S:Syndrome — a group of symptoms or illnesses that
occur as a result of HIV

Nov 2010
and STD Control
HIV versus AIDS
What is the difference between
HIV & AIDS?

Nov 2010
and STD Control
HIV versus AIDS (Continued)
• HIV: the virus that causes HIV infection
• AIDS: a group of serious illnesses and opportunistic
infections that occur when HIV has further
suppressed the immune system
• Most people who are HIV-infected will develop AIDS
after some time. It may be from several months to 15
years.

Nov 2010
and STD Control
Types of HIV
• HIV-1 and HIV-2
– Transmitted the same way
– Similar opportunistic infections
• HIV-1 more common worldwide
• HIV-2
– Found mainly in West Africa, Angola, and Mozambique. Few cases
reported in southern India.
– Less easily transmitted, HIV infection develops more slowly
– MTCT relatively rare with HIV-2

Nov 2010
and STD Control
CD4 & Viral Load
What are CD4 & Viral Load?

Nov 2010
and STD Control
CD4
• CD4 count: number of CD4 cells in the blood
• CD4 cell: a type of white blood cell that is the
immune system's key “infection fighter”
CD4 count reflects the “health” of the immune system

Nov 2010
and STD Control
CD4 (Continued)
• When HIV actively multiplies, it infects and kills CD4
cells.
• The CD4 count is expressed as the number of cells
per cubic millimetre.
– Normal count in healthy adult: 500−1500 cells/mm3
– Below 200 cells/mm3
: increased risk of serious HIV-
related infections

Nov 2010
and STD Control
CD4 & Viral Load (Continued)
• Viral load: amount of HIV in the blood
– Very high after initial infection with HIV
• High viral load = high risk of transmission of HIV
– When body develops antibodies to HIV, viral load falls
– As immune system gets weaker, viral load goes up again
– High viral load signals disease progression
– Measured with PCR test

Nov 2010
and STD Control
CD4 & Viral Load (Continued)

Nov 2010
and STD Control
Course of Infection:
Seroconversion
• Seroconversion: when person develops antibodies to
HIV, usually 4 to 6 weeks after becoming infected
– Flu-like illness may occur with seroconversion: fever, rash,
joint pain, enlarged lymph nodes
• “Window period”: the time between infection and
having enough antibodies to test positive for HIV

Nov 2010
and STD Control
Course of Infection
• Window period for adults: 3 months. A person who tests
HIV-negative, but who has had high risk behaviour in the past
3 months, should be tested again 3 months later, in case he
or she was in the “window period” during testing.
• Window period for babies: 6 weeks. Window period for
breastfeeding babies is 6 weeks. Babies should be tested for
HIV 6 weeks after stopping breastfeeding.

Nov 2010
and STD Control
Course of Infection (Continued)
• HIV-positive: A person whose blood test result is HIV-
positive has been infected by HIV.
– This person is seropositive or HIV-infected
• HIV-negative: A person whose blood test result is
HIV-negative is not infected with HIV.
– This person is seronegative

Nov 2010
and STD Control
Asymptomatic
• Asymptomatic: describes a person who is HIV-
infected but looks and feels healthy
• People who are asymptomatic can still pass HIV to
others
• Length of asymptomatic phase varies
– Some adults develop symptoms of HIV within a few
months; others may take up to 15 years to develop
symptoms
– Most children infected through MTCT develop symptoms
before they are 2 years old

Nov 2010
and STD Control
Symptomatic
• Person has physical signs of HIV and reports
symptoms of HIV
– Immune system weakens
– CD4 count decreases
– Progression of HIV depends on type of virus and specific
characteristics of person, including general health,
nutritional and immune status

Nov 2010
and STD Control
AIDS
• AIDS is the end stage of HIV infection
• Most people who are HIV-infected will ultimately
develop advanced HIV infection and AIDS
• As HIV infection progresses, CD4 count continues to
decrease and infected person becomes more likely to
develop opportunistic infections

Nov 2010
and STD Control
Opportunistic Infection (OI)
• People living with advanced HIV infection can suffer from OIs of the
brain, eyes, lungs, gut and other organs.
• Common OIs in persons diagnosed with AIDS:
– Tuberculosis
– Pneumocystis pneumonia (PCP)
– Cryptosporidiosis
– Other parasitic, viral, fungal infections
– Some cancers
An opportunistic infection (OI) is an illness caused
by a germ that might not cause illness
in a healthy person, but will cause illness in a person
with a weak immune system.

Nov 2010
and STD Control
Opportunistic Infection (OI)
Continued)

Nov 2010
and STD Control
Importances of Staging HIV
• Help determine when a patient needs ART
• Help determine when a patient needs Cotrimoxazole
• Help understand prognosis and guide patient counselling
• Help evaluate whether ART is working

Nov 2010
and STD Control
WHO Staging of HIV
• Clinical stages correspond to the natural course of HIV
infection
• Four clinical stages of HIV infection in children, adolescents,
and adults
– Clinical stage 1 (Asymptomatic)
– Clinical stage 2 (Mild)
– Clinical stage 3 (Advanced)
– Clinical stage 4 (Severe) = AIDS
Note: Staging will be discussed in detail in later session on Care, Treatment and Support Session

Nov 2010
and STD Control
Use of CD4
• Patients with severe immunodeficiency may not always
show clinical symptoms.
– CD4 counts can be used to start ART
– CD4 counts can be used to guide initiation of
cotrimoxazole
– CD4 can help identify ART treatment failure and the need
to switch to a second-line ART regimen.

Nov 2010
and STD Control
Routes of Transmission
How is HIV transmitted?

Nov 2010
and STD Control
Routes of Transmission
• Consider ALL sexually active men and women—and
adolescents—at risk for HIV infection.
• Pregnant women are at higher risk of contracting HIV
than non-pregnant women
– Hormonal changes affecting lining of genital tract
– Immune responses
• Warn all pregnant women of increased risk

Nov 2010
and STD Control
Routes of Transmission (Continued)
Encourage all pregnant women to
practise safer sex

Nov 2010
and STD Control
1. Unsafe sexual contact
– Unprotected sexual intercourse
– Contact with HIV-infected body fluids
during other sexual contact (oral and anal)
• Blood
• Semen
• Breast milk
• Cervical or vaginal secretions
• Other body fluids containing blood Heterosexual
intercourse is the most
common route of HIV
transmission globally

2. Injection drug use: sharing or re-using needles
• Blood and blood-borne products
–Transfusion
–Direct contact with HIV-blood through broken skin
–Occupational exposure
–Re-using sharp instruments to cut/pierce the skin during medical,
recreational, ceremonial, religious, or tatooing procedures

3. Mother-to-child transmission
(MTCT)
– During pregnancy
– During labour and delivery
– During breastfeeding

HIV is not transmitted by:
• Coughing or sneezing
• Touching or hugging
• Kissing
• Shaking hands
• Working or going to school
with a person who is HIV-
infected
• Sharing cups, glasses,
plates, or other utensils
• Being bitten by an insect
• Using the telephone
• Using public baths, pool,
or toilets
• Sharing water or food

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