• Protozoa causing diarrhea.
    • Oocysts are 4-6 µm in diameter and exhibit partial acid-fast staining.
  • Mostly commonly seen in HIV+
  • Most common cause of chronic diarrhea in HIV patients.

Environmental Exposures

  • Swim regularly in pools with insufficient sanitation.
  • Hikers who drink untreated water.
  • Handling infected cattle.

Clinical Features

Symptoms usually appear one week after infection which include:

Differential Diagnosis

Acute diarrhea



Watery Diarrhea

Traveler's Diarrhea


  • No eosinophilia
  • Stool acid-staining test
  • Stool Culture


  • If non-sick appearing and not immunocompromised, medication often not needed.[2]
  • Antiparasitics such as nitazoxanide for immunocompromised patients.[3]
  • IV/PO hydration if dehydration present.
  • If patient not on HAART therapy, consider contacting HIV/ID for initiating therapies, as disease is self-limited in CD4 > 200[4]
    • Diarrhea and fluid loss much worse in individuals with CD4 counts < 50.
  • Admission if severe dehydration or electrolyte imbalance.


  • Most of these patient's can be discharged with close primary care/HIV follow up.
  • If patient has electrolyte abnormalities or severely dehydrated consider observation placement vs admission for rehydration therapy

See Also

External Links


  1. Marx et al. “Cholera and Gastroenteritis caused by Noncholera Vibrio Species”. Rosen’s Emergency Medicine 8th edition vol 1 pg 1245-1246.
  2. White AC Jr. Cryptosporidiosis species. In: Mandell GL, Bennett JE, Dolin R, ed. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 209:3547-60.
  3. Lima AAM, Samie A, Guerrant RL. Cryptosporidiosis. In: Guerrant RL, Walker DH, Weller PF, eds. Tropical Infectious Diseases. Philadelphia, Pa: Elsevier-Churchill Livingstone; 2011:640-63.
  4. Cabada MM et al. Cryptosporidiosis Clinical Presentation. Aug 2018.