What are the stages of HIV (Human Immunodeficiency Virus) infection?

Stages of HIV Infection

HIV infection progresses through distinct clinical stages, beginning with acute infection, followed by clinical latency, and culminating in AIDS, with each stage having characteristic clinical manifestations and laboratory findings.

Stage 1: Acute HIV Infection (Primary HIV Infection)

• Occurs 2-4 weeks after initial infection
• Symptomatic in approximately 66-75% of patients 1
• Clinical manifestations:
  • Mononucleosis-like syndrome with fever, fatigue, lymphadenopathy
  • Rash, pharyngitis, myalgia, headache
  • Symptoms typically last 1-2 weeks but can persist longer
• Laboratory findings:
  • High viral load (HIV RNA)
  • Negative or indeterminate HIV antibody test
  • p24 antigen may be detectable 2
  • CD4+ T cell count may temporarily decrease

Stage 2: Clinical Latency (Asymptomatic HIV Infection)

• Follows acute infection and can last 3-10 years without treatment 3
• Clinical manifestations:
  • Often asymptomatic or mildly symptomatic
  • Persistent generalized lymphadenopathy may occur
  • Normal laboratory values may be present 4
• Laboratory findings:
  • Stable or gradually declining CD4+ T cell count
  • Detectable viral load
  • Positive HIV antibody test

Stage 3: Symptomatic HIV Infection

• Occurs as immune function deteriorates
• Clinical manifestations:
  • Constitutional symptoms (fever, weight loss, night sweats)
  • Oral candidiasis
  • Herpes zoster (shingles)
  • Bacterial infections
  • Seborrheic dermatitis and other skin conditions 5
• Laboratory findings:
  • CD4+ T cell count typically 200-500 cells/mm³
  • Increasing viral load

Stage 4: AIDS (Advanced HIV Disease)

• Defined by CD4+ T cell count <200 cells/mm³ or presence of AIDS-defining illnesses 5
• Clinical manifestations:
  • Opportunistic infections:
    • Pneumocystis jirovecii pneumonia
    • Tuberculosis
    • Cryptococcal meningitis
    • Toxoplasma encephalitis
    • Esophageal candidiasis
    • Cryptosporidiosis 5
  • AIDS-defining malignancies:
    • Kaposi's sarcoma
    • Non-Hodgkin lymphoma
    • Invasive cervical cancer
  • HIV wasting syndrome
  • HIV-associated dementia
• Laboratory findings:
  • CD4+ T cell count <200 cells/mm³ or CD4+ percentage <14% 5
  • High viral load

Natural History and Progression

• Without treatment, median progression from HIV infection to AIDS is approximately 10 years 5
• AIDS develops in 55-62% of untreated HIV-infected individuals within 12 years after infection 5
• Progression rates vary widely between individuals 4
• Factors affecting progression:
  • Viral factors (viral strain, virulence)
  • Host genetic factors
  • Age (faster progression in older individuals)
  • Presence of coinfections

Diagnostic Considerations

• Acute infection: HIV RNA testing is preferred; p24 antigen may be useful when RNA testing is unavailable 2
• Established infection: HIV antibody testing with confirmation by Western blot or other supplemental test 2
• CD4+ T cell count and viral load measurement are essential for staging and monitoring 2

Clinical Implications

• Early diagnosis allows for:
  • Timely initiation of antiretroviral therapy
  • Prevention of opportunistic infections
  • Reduction in HIV transmission risk 2
• Recognition of the stage of infection helps guide appropriate clinical management and patient counseling
• Understanding the natural history of HIV infection is crucial for predicting disease course and planning interventions