Clinical Care of HIV, AIDS and Opportunistic Infections Unit 1: Natural History of HIV Disease and...

Clinical Care of HIV, AIDS and Opportunistic Infections

Unit 1: Natural History of HIV Disease and Overview of Opportunistic Infections

Unit 1: Overview Slide 2Training on Clinical Care of HIV, AIDS and Opportunistic Infections

Learning Objectives

Participants will be able to:• Describe the natural history of HIV and AIDS

in adolescents and adults• Use the 2006 WHO clinical staging of HIV• Explain the meaning of ‘opportunistic’

infection or disease• Explain how CD4 lymphocyte count results

are used in developing a differential diagnosis


Definitions

• HIV• Human Immunodeficiency Virus

• Two types: HIV-1, HIV-2. • HIV-1 is the cause of the world-wide pandemic• Multiple HIV-1 subtypes or clades• Clades C and A are most common in southern Africa

• Clinical meaning - Can refer to persons with asymptomatic infection or symptomatic disease.

• HIV/AIDS• Used by MOHSS to describe the epidemic as a whole;

WHO is moving away from this term


Definitions (2)

• AIDS• Acquired Immunodeficiency Syndrome• Although used by the public to encompass the

whole epidemic, in the clinical sense it refers only to the most severe manifestation of infection with HIV

• Defined by the presence of life-threatening AIDS-defining conditions due to HIV-induced severe immunosuppression

• Opportunistic infections

• Some malignancies


Definitions (3)

• 2006 WHO definitions • Advanced HIV infection (most relevant for

patient management)• WHO Clinical Stage 3 or 4

– OR

• CD4 count < 350 cells/mm3

• AIDS• WHO Clinical Stage 4

» OR

• CD4 count < 200 cells/mm3


Question 1

• How long do people live after they acquire HIV infection, without HAART?

• How long does it take for a person with HIV to develop AIDS?


CD4 Count, Viral Load and Clinical Course of Untreated HIV Infection in Adults

Pla

sma

HIV

RN

A

Viral Load

CD4 Cells

4-8 Weeks 5-10 Years to AIDS

CD

4 Cell

Co

un

t

1,000

500

Intermediate Stage AIDS

Primary Infection

Sero-conversion

Survival with AIDS 1 year

200

1

10

100

1,000

10,000

100,000

1,000,000

10,000,000


Natural History High Viral Load: Rapid Progressor

Normal

AIDS

Infection 2-3 years

CD4 cells> 500

CD4 cells< 200

High Viral Load


Natural History Low Viral Load: Long-Term Non-Progressor

Normal

Infection 10 years

CD4 cells> 500

Low Viral Load


Question 2

• What is the meaning of ‘opportunistic’ infection or disease?


Opportunistic Disease or Infection

Strict meaning:• An infection or disease that occurs only in

persons with weakened immune systems

Common meaning:• Any one of a number of infections or diseases

that occur often in persons with HIV or AIDS

Unit 1: Overview Slide 12Training on Clinical Care of HIV, AIDS and Opportunistic InfectionsWHO, 2006. http://www.who.int


Natural History:WHO Immunological Classification of HIV Infection

CD4 cellsCD4 cells>> 500 500

CD4 cellsCD4 cells499-350499-350


No significant No significant immunosuppressionimmunosuppression

MildMildimmunosuppressionimmunosuppression

Advanced immuno-Advanced immuno-suppressionsuppression

CD4 cellsCD4 cells< 200< 200

Severe immuno-Severe immuno-suppressionsuppression


Question 3

• How can you use CD4 lymphocyte count results in developing a differential diagnosis?


Relation Between CD4 Count and Types of Pathogens

CD4 cellsCD4 cells> 500> 500



Usual pathogensUsual pathogens

Usual pathogens;Usual pathogens;disease more frequent or disease more frequent or severesevere

Opportunistic Opportunistic pathogenspathogens


‘‘Severe’Severe’opportunistic opportunistic pathogenspathogens


Examples of Pulmonary Pathogens

CD4 cell count Pathogen Examples

> 500 UsualBacterial pneumonia

TB

500-200

Usual

More frequent

More severe

Bacterial pneumonia

TB

200-50 OpportunisticPneumocystis

TB

< 50 Opportunistic

MOTT or TB

CMV

Kaposi’s Sarcoma


Distribution of HIV Infected Persons and Levels of Immunosuppression

Stage 1

Stage 2

Stage 3

Stage 4 AIDS

Advancedimmunosuppression

No significantimmunosuppression

Mildimmunosuppression


Key Points

• Persons with HIV may have normal immune function, or varying degrees of immunodeficiency

• Knowledge of the degree of immunodeficiency in an HIV+ person helps determine which infections or diseases are most likely

• The CD4 lymphocyte count, if available, helps determine the degree of immunodeficiency

• Staging of HIV disease is based on clinical factors, not CD4 counts

Clinical Care of HIV, AIDS and Opportunistic Infections Unit 1: Natural History of HIV Disease and...

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