Other Specimens - Aspirates
Duodenal aspirates may be useful in demonstrating Giardia duodenalis or Strongyloides stercoralis larvae. Material collected following intubation through the nose and stomach into the upper small intestine may be submitted to the laboratory. Centrifuge the specimen at 500 × g for 2 to 3 minutes and examine the wet mount. An unfixed specimen can be examined immediately or if the specimen cannot be examined within 1 to 2 hours after collection, it should be preserved in 10% formalin.
Sigmoidoscopy material and abscesses of the liver and lung may demonstrate amebic trophozoites. Material from the mucosal surface or from visible lesions should be aspirated. This material can be examined immediately in a 0.85% saline wet mount preparation (or part of this material could be placed in formalin) or can be fixed in PVA. Once fixed in PVA, the material can be stained using trichrome stain and examined for trophozoites of Entamoeba histolytica. A real-time PCR test is available for confirmation of amebiasis that detects E. histolytica at the species level. If molecular diagnosis is necessary, specimens should be unpreserved and kept refrigerated or frozen.
Lymph node material, bone marrow, and spleen may be examined for the presence of motile trophozoites of Trypanosoma brucei gambiense or Trypanosoma brucei rhodesiense. For Leishmania donovani infections, material obtained by needle aspiration from bone marrow or spleen can be used to demonstrate amastigote stages. Smears can then be prepared by fixing in methanol and staining with Giemsa stain.
Skin ulcers may demonstrate the amastigote stages in cutaneous and mucocutaneous leishmaniasis. Permanent stained smears made with these specimens by fixing in methanol and staining with Giemsa stain.
For additional information about aspirates, call the Division of Parasitic Diseases, at (404) 718-4110.
DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/.