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

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

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

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

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

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

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

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

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

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

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