Page 72 - AIDSBK23C

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HIV Infection, Stage 1

No AIDS-defining condition and either CD4+ T-lymphocyte count of >500 cells/µL or
CD4+ T-lymphocyte percentage of total lymphocytes of >29.

HIV Infection, Stage 2

No AIDS-defining condition and either CD4+ T-lymphocyte count of 200--499 cells/µL
or CD4+ T-lymphocyte percentage of total lymphocytes of 14--28.

HIV Infection, Stage 3 (AIDS)

CD4+ T-lymphocyte count of <200 cells/µL or CD4+ T-lymphocyte percentage of total
lymphocytes of <14 or documentation of an AIDS-defining condition (see below).
Documentation of an AIDS-defining condition supersedes a CD4+ T-lymphocyte count
of >200 cells/µL and a CD4+ T-lymphocyte percentage of total lymphocytes of >14.
Definitive diagnostic methods for these conditions are shown below from the 1993
revised HIV classification system and the expanded AIDS case definition and from the
U.S. National Notifiable Diseases Surveillance System.

HIV Infection, Stage Unknown

No information available on CD4+ T-lymphocyte count or percentage and no information
available on AIDS-defining conditions. (Every effort should be made to report CD4+ T-
lymphocyte counts or percentages and the presence of AIDS-defining conditions at the
time of diagnosis.)

A diagnosis of acute HIV infection indicates documented evidence of detectable HIV RNA or
DNA or of p24 antigen in plasma or serum in the presence of a documented negative or
indeterminate result from an HIV antibody test. These laboratory tests should be conducted on
the same specimen or on specimens obtained on the same day. Acute HIV infection occurs
approximately during the time from viral acquisition until seroconversion (i.e., the development
of measurable levels of HIV-specific antibodies). During this period, early immune responses to
the virus produce distinctive characteristics; 40% to 80% of patients develop clinical symptoms
of a nonspecific viral illness (e.g., fever, fatigue, or rash) typically lasting 1--2 weeks.

2008 Surveillance Case Definition for HIV Infection Among Children Aged <18 Months

The 2008 definition takes into account new available testing technologies. Because
diagnostic laboratory testing for HIV infection among children aged <18 months might
be unreliable, children in this age group with perinatal HIV exposure whose illness meets
the AIDS case definition on the basis of clinical criteria are considered presumptively
HIV infected when the mother has laboratory-confirmed HIV infection. The definitive or
presumptive exclusion of HIV infection for surveillance purposes does not mean that