HIV vs AIDS: Understanding the Distinction
HIV (Human Immunodeficiency Virus) is the virus that causes AIDS (Acquired Immunodeficiency Syndrome), which is the advanced stage of HIV disease defined by severe immunosuppression. 1
HIV: The Causative Virus
HIV is a retrovirus belonging to the lentivirus subfamily that chronically infects humans, primarily targeting CD4+ T-helper lymphocytes and cells of monocyte/macrophage lineage. 1, 2
Key characteristics of HIV infection:
- Chronic lifelong infection that persists once acquired, with the virus integrating its genetic material (proviral DNA) into the host cell's genome. 2
- Detectable through antibody testing, with the presence of antibodies to HIV indicating active infection. 1
- Transmitted through genital sexual contact, blood exposure (including intravenous drug use), perinatal transmission (approximately 30% of infants born to infected mothers), and rarely through breast-feeding. 2
- Progressive destruction of the T-helper lymphocyte population occurs over years, measured typically in the range of 8 years on average without treatment. 3, 2
AIDS: The Advanced Disease Stage
AIDS is not a separate disease entity but rather the end-stage manifestation of untreated HIV infection, defined by specific clinical and laboratory criteria. 1
CDC Surveillance Definition of AIDS (Effective 1993)
The CDC expanded the AIDS case definition to include HIV-infected adolescents and adults aged ≥13 years who meet any one of the following criteria: 1
- CD4+ T-lymphocyte count <200 cells/μL 1
- CD4+ T-lymphocyte percentage <14% of total lymphocytes 1
- Presence of any AIDS-defining clinical condition, including:
Critical Clinical Distinctions
Timeline and Progression
- HIV infection begins immediately upon viral transmission and establishment of chronic infection. 2
- Asymptomatic intervals averaging 8 years typically occur between HIV infection and AIDS development in untreated individuals. 3
- AIDS represents advanced immunosuppression where the immune system can no longer protect against opportunistic infections and certain malignancies. 1, 4
Treatment Impact on Disease Progression
The introduction of highly active antiretroviral therapy (HAART) has fundamentally altered the natural history of HIV disease: 1
- Slowed progression from HIV to AIDS in treated individuals. 1
- Reduced AIDS incidence dramatically in populations with widespread HAART access. 1
- HIV-infected persons on effective treatment may never progress to AIDS if viral suppression is maintained and CD4 counts remain above threshold levels. 1
Surveillance and Public Health Implications
The CDC recommends expanded surveillance to include both HIV infection and AIDS cases because: 1
- AIDS surveillance alone no longer adequately reflects HIV transmission trends due to treatment effects. 1
- Monitoring all stages of HIV disease is necessary for resource allocation, prevention efforts, and evaluating public health interventions. 1
Common Clinical Pitfalls
Do not assume that all HIV-positive individuals will develop AIDS—with effective antiretroviral therapy, progression can be prevented indefinitely. 1, 5, 6
Do not confuse HIV with HTLV (Human T-lymphotropic virus), which is a different retrovirus that does not cause AIDS. 1
Do not delay treatment based on CD4 count alone—current guidelines emphasize early antiretroviral therapy initiation for all HIV-infected individuals regardless of CD4 count to prevent progression to AIDS. 5, 6
Recognize that persons with HIV infection remain infectious throughout all stages of disease, including when asymptomatic and even when virally suppressed on treatment, though transmission risk is dramatically reduced with effective viral suppression. 5, 6, 2