HIV i-Base • STEP • EATG
HIV Training for Advocates
Section 1&2: CD4 and Viral Load
Reduced slide set
HIV i-Base: Training for Advocates, 10/2004
www.i-Base.info
CD4 count.1
•
CD4 count - Marker for immune damage caused by HIV.
Measured as ‘cells/mm3’
•
HIV-negative range 600-1200.
•
Declines ~50-100 cells/year - AVERAGE
•
Closely matches the risk for becoming ill and used to
provide prophylaxis treatment
• >300 - very few HIV-related problems, except cancers (KS, NHL, lymphoma at any count).
Reduced response to vaccinations.
• 200–300 - water and food bourn problems (microsporidia, crytosporidia) + skin problems
• <200 - PCP
• <100 - MAI, MAC, toxoplasmosis
• <50 - CMV + increased risk for everything else
HIV i-Base: Training for Advocates, 10/2004
www.i-Base.info
CD4 count.2
•
Used for deciding when to start HIV treatment - historical
UK (2003) - when ≥ 200 cells/mm3 - (EuroSIDA)
US (2003) - when ≥350 cells/mm3 (from 2003)
•
Used for deciding when to stop treatment
•
Used to monitor and treat with prophylaxis
One test result means nothing by itself - you need to follow
results over time and the trend of any changes
•
CD4% is the % of lymphocytes that are CD4 cells - the %
can be more stable than count
•
Other factors: smoking, time of day, exercise, fatty meal
HIV i-Base: Training for Advocates, 10/2004
www.i-Base.info
CD4 history after HIV infection
[without treatment]
Death
Seroconversion
Infection
Asymptomatic
Symptomatic AIDS
1000
CD4+
Cells/mm
500
200
0
4-8 wks 2-12 mo
Up to 12 years
2-3 years
Time
HIV i-Base: Training for Advocates, 10/2004
www.i-Base.info
CD4 history after HIV infection
[without treatment]
Death
Seroconversion
Infection
Asymptomatic
Symptomatic AIDS
1000
CD4+
Cells/mm3
Start treatment before
CD4 goes below 200 cells/mm3
500
200
0
4-8 wks 2-12 mo
HIV i-Base: Training for Advocates, 10/2004
Up to 12 years
Time
2-3 years
www.i-Base.info
Viral load.1 (HIV RNA)
1. Measures level of virus (copies/mL) - usually in blood
2. New technology. Individualise care. Now widely used in
other viral infections - (but scale of results is different) (ie
with HCV is usually measure in millions)
3. Can influence when to start treatment (ie if ‘high’
>100,000 copies/mL then predictive of progression), and
in choice of treatment
4. 3-fold margin of error (ie 30,000 could be anywhere
between 10,000 and 90,000 and still count as the same
result)
5. This is the most important test when on-treatment
HIV i-Base: Training for Advocates, 10/2004
www.i-Base.info
Viral load.2 (HIV RNA)
When on-treatment:
• viral load tests tell you if your treatment works
• when your treatment fails
• Whatever the starting level (baseline) - aim to get
viral load to under 50 copies/mL (by3-6 months)
• If still detectable resistance will develop and
guidelines recommend changing treatment
HIV i-Base: Training for Advocates, 10/2004
www.i-Base.info
Viral load after HIV-1 Infection
[without treatment]
Death
Seroconversion
Infection
Asymptomatic
Symptomatic AIDS
2 million
viral load
copies/mL
0
4-8 wks 2-12 mo
Up to 12 years
2-3 years
Time
HIV i-Base: Training for Advocates, 10/2004
www.i-Base.info
Viral load after HIV-1 Infection
[without treatment]
Death
Seroconversion
Infection
Asymptomatic
Symptomatic AIDS
2 million
1000
CD4+
Cells/mm3
viral load
copies/mL
500
200
0
0
4-8 wks
2-12 mo
Up to 12 years
2-3 years
Time
HIV i-Base: Training for Advocates, 10/2004
www.i-Base.info
After HIV treatment (ARVs):
effect on CD4 and viral load
Start treatment
Viral load <50 copies/mL
2 million
1000
CD4+
cells/mm3
viral load (RNA)
copies/mL
500
200
< 50 copies/mL
0
0
+ 1-40+ years !!
1-12 yrs +1-6 mo
Chronic
Infection
HIV i-Base: Training for Advocates, 10/2004
Time
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