Table 3 Diagnostic tests for important intestinal protozoa that may cause persistent digestive disorders

Balantidium coli

Stool microscopy

-

-

-

[55]

· Wet mount smears (unstained or iodine stain)

· Concentration techniques (e.g. formalin-ether)

· Permanent stains (e.g. with iron hematoxylin)

Blastocystis hominis

Stool microscopy

Stool culture on selective liquid media (no routine procedure, but beneficial in microscopically uncertain cases)

(No routine procedure)

(PCR mainly applied in research settings)

[56–58]

· Wet mount smears (unstained or iodine stain)

· Permanent stains (e.g. with trichrome, iron hematoxylin, Giemsa)

Cryptosporidium spp.

Stool microscopy

(No routine procedure)

· ELISA: faecal antigen detection

PCR (in reference laboratories and for species differentiation)

[59–62]

· Wet mount smears (unstained or iodine stain)

· Fluorescence microscopy

· Various staining techniques, especially acid-fast stains (e.g. Kinyoun, modified Ziehl-Neelsen)

Cyclospora cayetanensis

Stool microscopy

(No routine procedure)

-

PCR (in reference laboratories)

[63]

· Wet mount smears (light or epifluorescence microscopy)

· Concentration techniques (e.g. formalin-ether)

· Acid-fast stains (oocysts are variably acid-fast)

Dientamoeba fragilis

Stool microscopy on stained smears (e.g. iron-hematoxylin, chlorazol black dye stain)

(No routine procedure)

-

PCR (in reference laboratories) on unpreserved stool samples

[64, 65]

Entamoeba histolytica

Stool microscopy

(No routine procedure)

· ELISA: faecal antigen detection able to distinguish between E. histolytica and E. dispar/moshkovskii (stool)

PCR (in reference laboratories)

[66–70]

· Wet mount smears (trophozoites)

· Serological antibody detection tests (blood samples)

· Formalin-ether concentration (cysts)

· Permanent stains

Giardia intestinalis

Stool microscopy

(No routine procedure)

· ELISA: faecal antigen detection

PCR (in reference laboratories)

[60, 71]

(syn.: G. lamblia and G. duodenalis)

· Wet mount smears (trophozoites)

· Formalin-ether concentration (cysts)

· Permanent stains

Isospora belli (syn.: Cystoisospora belli)

Stool microscopy

-

-

PCR (in reference laboratories)

[60, 72, 73]

· Wet mount smears

· Concentration techniques (e.g. formalin-ether)

· Acid-fast stains

Species of microsporidia (Enterocytozoon bieneusi, Encephalitozoon spp.)

· Transmission electron microscopy (gold standard, but not feasible as routine test)

-

Serology: anti-microsporidial antibodies (indirect immunofluorescence assay)

PCR (in reference laboratories)

[60, 74–76]

- Light microscopy (e.g. Uvitex B, Chromotrope R or Calcofluor White stain)