1. Phases of HIV/AIDS
1. Infection 2. Window period 3. Seroconversion 4. Asymptomatic period 5. HIV/AIDS - related illness 6. AIDS

2. CD4 counts
Number of CD4 cells in blood provides a measure of immune system damage
CD4 count reflects phase of disease
CD4 count:
500 – 1200: Normal
200 – 500: Beginning of HIV illness
< 200: AIDS

3. Window period
Time between infection & enough antibodies for a positive HIV test
Duration: approximately 3 months
No symptoms or signs of illness
HIV test is negative
Virus is multiplying rapidly - viral load is high
Person is very infectious

4. Seroconversion Point at which HIV test becomes positive
Body starts making antibodies to HIV a few weeks after infection
HIV test becomes positive when antibody levels are high enough to be measured
Happens about 3 months after infection
Person may have a mild flu-like illness, lasting a week or two
Afterwards, the person is well again

5. Asymptomatic period
Time period between seroconversion and onset of HIV/AIDS-related illness
Duration variable: < 1 year to > 15 years
Most people remain healthy (asymptomatic) for about three years
Duration may depend on socio-economic factors
The CD4 count is above 500 cells/ml

6. HIV/AIDS-related illness
Time period between onset of illness & diagnosis of AIDS
Duration is variable: average about 5 years
Illnesses initially mild, with gradual increase in frequency and severity
CD4 count is between 500 & 200 cells/ml

7. AIDS Final phase of HIV/AIDS Duration:
without antiretroviral drugs, less than 2 years
with antiretrovirals, potentially many years
CD4 count is below 200 cells/ml
Viral loads are high & the person is very infectious
HIV test may become negative

8. Phases of HIV/AIDS
1. Infection: The moment the virus gets into the body 2. Window period: The time between infection & enough antibodies for a positive HIV test 3. Seroconversion: The body starts to make antibodies to HIV

9. Phases of HIV/AIDS
4. Asymptomatic period: No illness 5. HIV/AIDS-related illness: Less serious illnesses 6. AIDS: Serious illnesses

10. Important facts
Duration of different phases of HIV/AIDS will vary in different people
It is not possible to predict the course of the disease in any one person
Factors affecting the course of HIV/AIDS include nutrition, emotional stress, and access to health care
People infected with HIV can infect others at any phase of the disease

11. Re-infection Different strains of HIV exist within the same HIV type
It is possible to be re-infected with a different strain
When re-infection occurs, the immune system is weakened more rapidly
NB Re-infection can hasten the progression of the disease