Parasites (other) – Entamoeba histolytica

Serologic and/or microscopic Identification of Entamoeba histolytica
Microbiology
Parasitology
Microscopy ○ Aspirates/pus ○ Stool Serology ○ Whole blood ○ Serum
Other Information
○ Collect 1 specimen per day (1 Yellow top and 1 White top container) for 3 days in each vial for a total of six (6) specimens per patient with suspected parasitic infection.

○ Ensure patient avoids anti-diarrheal medications, radiological dye (barium) and antibiotics prior to producing the specimen as they may interfere with parasite detection.
○ The fecal antigen is the standard reference method at PHOL to differentiate between E. histolytica and the identical non-pathogen E. dispar. This test will be done following a positive SAF preserved faecal specimen, but can be requested for liver abscesses. This test will not be done if the patient is treated for an Entamoeba infection or as a follow-up specimen.

○ Please provide appropriate clinical information on the requisition (e.g. travel history or country of origin if refugee, returned traveller or recent immigrant, consumption of certain food products, eosinophilia, HIV, immunocompromise, critical illness, admitted to ICU or previous parasite infection

○ Acute and convalescent sera (collected 2-3 weeks apart) may be necessary for laboratory diagnosis
○ Aspirates/pus: sterile container (min volume 0.5 mL)
○ Stool: Parasitology Kit (3 each of SAF yellow top vial, white top sterile vial) (1g)
○ Whole blood/serum: serum separator tube (clotted blood) (min volume 5 mL

Aspirates/pus
○ Aspirates or pus from abscesses or other sterile sites should be collected aseptically through decontaminated skin using a syringe and needle and placed in a sterile container.

Stool
○ Collect stool immediately after bowel movement in a dry, clean container (e.g. Chamber pot, wide-mouth jar, pie plate, newspaper, or saran wrap on toilet seat). Follow instructions below to add specimen to BOTH yellow and white capped containers. Specimen should not be contaminated with urine or toilet water.
Container 1 SAF (Yellow top) vial:
○ Use plastic spork attached to lid to add sample (from beginning, middle and end of stool) to yellow capped bottle so that the preservative fluid level is approximately ¾ full. Mix thoroughly by shaking. Ratio should be 1 part solid stool to 3 parts SAF or 1 part liquid faeces to 1 part SAF.

Container 2 Sterile (White top) vial:
○ Using plastic spork, Add stool directly to sterile white capped container.

Whole blood/serum
○ Decontaminate skin with 70% alcohol followed by iodine or chlorhexidine, collect at least 5 mL of blood into appropriate container

Refer to section Sample Processing / Delivery
PHOL
○ Microscopy: 3-5 days from receipt at PHOL
○ Serology: Up to 10 days from receipt at PHOL
416-586-4800 extension 4593
NO
○ Label specimen container. Place specimens in biohazard bag and seal.

○ Specimens should be stored at room temperature (20-25˚C) and transported to the UHN/SH Microbiology Laboratory ASAP after collection. For stool, keep Yellow top tube (SAF vial) at room temperature while the White-top vial should be refrigerated (2-8˚C) prior to transport. Serology specimens should be stored at refrigeration temperature.

○ The specimen will be referred to the Public Health Ontario Laboratory for testing