Toxoplasma gondii vs Cryptosporidium
How to tell Toxoplasma gondii and Cryptosporidium apart when a board question makes them look alike.
Toxoplasma is cat or meat exposure with brain or congenital disease; Cryptosporidium is acid-fast waterborne watery diarrhea, severe in low CD4.
Side by side
Toxoplasma causes ring-enhancing brain lesions in advanced HIV, congenital chorioretinitis, hydrocephalus, intracranial calcifications, and risk from cat feces or undercooked meat.
Cryptosporidium causes watery diarrhea that is self-limited in immunocompetent hosts but chronic, severe, and biliary in advanced immunosuppression.
Toxoplasma is an intracellular protozoan acquired from oocysts or tissue cysts and controlled mainly by cell-mediated immunity.
Cryptosporidium oocysts are acid-fast and chlorine-resistant, infect intestinal epithelium, and cause secretory watery diarrhea.
Multiple ring-enhancing basal ganglia lesions, positive Toxoplasma IgG, congenital triad, or tachyzoites/bradyzoites support toxoplasmosis.
Modified acid-fast oocysts in stool, waterborne outbreak, chronic watery diarrhea, low CD4, or sclerosing cholangitis-like biliary disease support cryptosporidiosis.
The trap
Both matter in immunocompromised patients, but toxoplasma targets brain and fetus while cryptosporidium targets gut and biliary tract.
The repair move
For immunocompromised protozoa, match the organ system first: brain lesions versus watery diarrhea.
Try a free question
CoreA patient with AIDS has headache, confusion, focal weakness, positive Toxoplasma IgG, and multiple ring-enhancing basal ganglia lesions. Which organism is most likely?
Show answer and explanation
Answer: A. Toxoplasma gondii. Multiple basal ganglia ring-enhancing lesions in advanced HIV support toxoplasmosis.
Why the other choices are tempting
- B. Cryptosporidium causes watery diarrhea and biliary disease in low CD4.
- C. Giardia causes greasy malabsorptive diarrhea.
- D. Entamoeba causes dysentery and liver abscess.
- E. P. malariae causes chronic quartan malaria.
Flashcards
Tap a card to flip it.
What brain imaging pattern supports toxoplasmosis in AIDS?
Multiple ring-enhancing lesions, often in the basal ganglia, support toxoplasmosis.
What congenital triad supports toxoplasmosis?
Chorioretinitis, hydrocephalus, and intracranial calcifications support congenital toxoplasmosis.
Quick answers
What is the fastest way to tell Toxoplasma gondii from Cryptosporidium?
Toxoplasma is cat or meat exposure with brain or congenital disease; Cryptosporidium is acid-fast waterborne watery diarrhea, severe in low CD4.
What is the key clue for Toxoplasma gondii?
Toxoplasma causes ring-enhancing brain lesions in advanced HIV, congenital chorioretinitis, hydrocephalus, intracranial calcifications, and risk from cat feces or undercooked meat.
What is the key clue for Cryptosporidium?
Cryptosporidium causes watery diarrhea that is self-limited in immunocompetent hosts but chronic, severe, and biliary in advanced immunosuppression.
What is the common trap with Toxoplasma gondii vs Cryptosporidium?
Both matter in immunocompromised patients, but toxoplasma targets brain and fetus while cryptosporidium targets gut and biliary tract.