• Clinical science

HIV-associated conditions


AIDS (acquired immunodeficiency syndrome) is the final stage of HIV infection and is defined by the development of certain diseases (AIDS-defining conditions) or a CD4 cell count of < 200 cells/μL in HIV-infected patients. AIDS-defining conditions include malignancies (e.g., primary lymphoma of the brain) and certain opportunistic infections (e.g., Pneumocystis pneumonia, cerebral toxoplasmosis). There are also opportunistic infections that commonly occur in HIV patients that are not considered AIDS-defining conditions. This article provides an overview of AIDS-defining and other HIV-associated conditions.

Overview of HIV-associated conditions

AIDS-defining conditions

The CDC defines AIDS as the development of an AIDS-defining condition or a CD4 cell count of < 200 cells/μL in HIV-infected patients.

AIDS-defining condition CD4 count (in cells/μL) Features Management

HIV wasting syndrome

  • Variable
  • Unintentional weight loss of ≥ 10%, fatigue, fever, diarrhea
  • Caused by various factors (e.g., diarrhea due to secondary infection, reduced appetite, changes in metabolism)
  • Optimization of nutrition
  • Prevention of nausea/vomiting
  • Treatment of gastrointestinal infections (e.g., CMV colitis)
Kaposi sarcoma
  • Variable (typically < 500/mm3)
Cervical cancer (invasive)
  • Variable
Reactivation tuberculosis
  • < 400
  • < 250
  • < 100
  • Chronic, watery diarrhea with nausea and abdominal pains
  • Acid-fast cysts in stool
HIV-related encephalopathy (AIDS dementia)
  • < 200 (typically untreated patients with advanced HIV infection)
  • Subcortical dementia
  • See “HIV-associated CNS lesions” below for details.
  • Optimize antiretroviral treatment, but avoid efavirenz
Progressive multifocal leukoencephalopathy (PML)
  • < 200
  • Focal-neurologic deficits, altered mental status, impaired vigilance
  • MRI: disseminated, non-enhancing white matter lesions without mass effect
  • Supportive
Pneumocystis pneumonia
  • < 200
  • Most common cause of death in patients with AIDS!
  • Gradual onset with low-grade fever, dyspnea and non-productive cough
  • Laboratory: beta-D-glucan
  • CXR: diffuse bilateral infiltrates (“ground-glass appearance)
  • < 200
  • < 150
Cerebral toxoplasmosis
  • < 100
Cryptococcosis (extrapulmonary, especially cryptococcal meningitis)
  • < 100


  • < 100
Herpes simplex infections
  • < 100
Cytomegalovirus infection
  • < 50
Tuberculosis-like disease
  • < 50
  • Caused by Mycobacterium avium complex (MAC) infection
  • Cough, sputum, weight loss, night sweats, fever

Other HIV-associated conditions

Adequate HIV treatment (cART) is key to minimizing the risk of opportunistic infections!

Some AIDS-defining conditions are opportunistic infections, but the terms are not interchangeable!


Mycobacterium avium complex (MAC) infection


Progressive multifocal leukoencephalopathy (PML)


Kaposi sarcoma


Bacillary angiomatosis


HIV-associated ocular manifestations

Features CD4 count
HIV retinopathy
  • Caused by a microvascular disorder
  • Fundoscopic findings
  • Tend to self-resolve without progression
  • Not painful
  • Vision usually unaffected
  • Variable
Herpes simplex keratitis
  • History of HSV infection is common
  • Slit-lamp examination: dendritic corneal lesions
  • Fundoscopic findings are normal
  • Painful and watery eye(s)
  • Blurry vision
  • Variable
Varicella zoster retinitis
  • Rare
  • Fundoscopic findings: retinal necrosis (starting from the periphery)
  • Painful
  • Severe loss of vision
  • Variable
Cytomegalovirus retinitis
  • < 50/μL
Toxoplasma retinitis
  • Fundoscopic findings: raised yellow-white cottony lesions (distribution of the lesions not related to vessels)
  • Painful
  • Visual impairment
  • < 100/μL

HIV-associated CNS lesions

Differential diagnosis of CNS lesions in HIV-positive patients with CD4+ T-cell count < 200/mm3:

Conditions Description Clinical features Neuroimaging Further tests Treatment
Cerebral toxoplasmosis
Primary CNS lymphoma (PCNSL)
  • An extranodal non-hodgkin lymphoma
  • Associated with EBV infection
  • Headache
  • Focal neurologic deficits
  • Neuropsychiatric symptoms (e.g., personality changes)
  • Seizures (< 15%)
Cerebral abscess
Progressive multifocal leukoencephalopathy (PML)
  • Rapidly progressive focal-neurologic deficits (e.g., visual field defects, hemiparesis)
  • Cognitive impairment
  • Impaired vigilance
  • Supportive therapy
HIV-associated encephalopathy (AIDS dementia)
  • Dissemination of HIV into the CNS (particularly in advanced HIV infection and/or untreated patients)
  • Subcortical dementia (memory loss, depression, movement disorders)
  • Progression to severe neurologic deficits (impaired vigilance, aphasia, gait disturbances)
  • Antiretroviral therapy (cART)
  • Supportive therapy