AIDS fever of unknown origin


Sources of fever vary by stage of disease. The CD4 count of < 200 × 106 cells/μL is very likely if the ED absolute lymphocyte count is < 950 × 10(6) cells/μL and less likely if the absolute lymphocyte count is > 1,700 × 106 cells/μL[1]

HIV Associated Diseases by CD4 Level

CD4 Count Stage Diseases
>500 Early disease Similar to non-immunocompromised patients (Consider HAART medication side-effects)
200-500 Intermediate disease Kaposi's sarcoma, Candida, bacterial respiratory infections
<200 Late disease PCP, central line infection, MAC, TB, CMV, drug fever, sinusitis, endocarditis, lymphoma, histoplasmosis, cryptococcus, PML
<100 Very late disease Cryptococcus, Cryptosporidium, Toxoplasmosis
<50 Final Stage CMV retinitis, MAC

CD4 >500

  • Work-up similarly to nonimmunocompromised patients

CD4 200-500

  • Early bacterial respiratory infection most common

CD4 <200

  • PCP, central line infection, MAC, TB, CMV, drug fever, sinusitis
  • Also consider: endocarditis, lymphoma, histo, crypto

CD4 <100

Differential Diagnosis

HIV associated conditions


  • CBC
  • Chemistry
  • LFT
  • LDH
  • RPR
  • Urinalysis/Urine cultures
  • Blood cultures
    • Aerobic, anaerobic, fungal
  • Crypto
  • Toxo
  • Coccidiodomycosis
  • CXR
  • Stool culture / O&P
  • CT
  • LP
    • Cell count, protein, glucose, VDRL, cryptocoocal antigen, cytology, toxo, CMV, JC, EBV



See Also


  1. Napoli AM et al. Absolute lymphocyte count in the emergency department predicts a low CD4 count in admitted HIV-positive patients. Acad Emerg Med. 2011 Apr;18(4):385-9.
  2. Gutteridge, David L MD, MPH, Egan, Daniel J. MD. The HIV-Infected Adult Patient in The Emergency Department: The Changing Landscape of the Disease. Emergency Medicine Practice: An Evidence-Based Approach to Emergency Medicine. Vol 18, Num 2. Feb 2016.