Case 18. Isospora belli infection (45 y-o M)
    Duodenal biopsy from a patient suffering from a long-standing intractable diarrhea    
Key words : 
Isospora belli, intractable enteritis, celiac disease, microsporidiosis    
Severe chronic inflammation with shortening of the duodenal villi (HE)   Schizonts are distributed among the intestinal columnar epithelium (HE). Eosinophils are increased in the mucosa.
Schizonts and merozoites are seen among the intestinal epithelium (HE).   Patient's own serum diluted at 1:100 detects the protozoan pathogens among the epithelium (immunostaining = indirect immunoperoxidase).
Reference case 18A
Celiac disease (gluten intolerance), duodenal biopsy from a 25 y-o African. Marked duodenal inflammation and villous atrophy are seen, but without accompanying pathogens (HE).
  Reference case 18B
Microsporidiosis (Encephalitozoon cuniculi infection) in an ascites macrophage of the immunosuppressed mouse. Finely granulated pathogens are clustered in the macrophage (Gomori's trichrome).
Reference case 18C
Microsporidiosis (Enterocytozoon bieneusi infection) opportunistically infected in AIDS.
Electron micrograph of the duodenal epithelium containing a cluster of tear drop-shaped spores which contain coiled polar tubules.