The Relationship between the Human Immunodeficiency Virus and the Acquired Immunodeficiency Syndrome (Draft)

DRAFT
(CDC, 1992a). This surveillance definition replaces criteria published in 1987 that were based
on clinical conditions and evidence of HIV infection but not on CD4+ T cell determinations
(CDC, 1987a).
In children younger than 13 years, the definition of AIDS is similar to that in
adolescents and adults, except that lymphoid interstitial pneumonitis (LIP) and recurrent
bacterial infections are included in the list of AIDS-defining conditions (CDC, 1987b).
The CDC classification system is used both in Europe and the United States. In many
developing countries, where diagnostic facilities may be minimal, epidemiologists employ a
case definition based on the presence of various clinical symptoms associated with immune
deficiency and the exclusion of other known causes of immunosuppression, such as cancer or
malnutrition (Ryder, 1994; Davachi, 1994).
Surveillance definitions of AIDS have proven useful epidemiologically to track and
quantify the recent epidemic of HIV-mediated immunosuppression and its manifestations.
However, as discussed above, AIDS represents only the end stage of a continuous,
progressive pathogenic process, beginning with primary infection with HIV, continuing with a
chronic phase and asymptomatic infection, and leading to progressively severe symptoms
and, ultimately, profound immunodeficiency (Fauci, 1993a). In clinical practice,
symptomatology and measurements of immune function, notably levels of CD4+ T
lymphocytes, are used to guide the treatment of HIV-infected persons rather than an all-ornothing paradigm of AIDS/non-AIDS (Volberding, 1992; Sande et al., 1993; CDC, 1992a).
Between June 1981 and June 30, 1994, 401,749 cases of AIDS, including 243,423
AIDS-related deaths were reported to the CDC (CDC, 1994a). AIDS is now the leading cause
of death among men aged 25 to 44 in the United States, and the fourth leading cause of
death among women in the same age group (CDC, 1993c; Selik et al., 1993, Vermund,
1 993b).

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