Worm (Whole or Segment) – Identification

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

Background
This page provides information for identification of visible worms or worm segments submitted at Public Health Ontario (PHO). These visible worms may be spontaneously expelled or removed through procedures such as endoscopy.

Visible worms or worm segments in the gastrointestinal tract may include immature or adult stages of various helminths. These can be observed with the naked eye and include: Enterobius (pinworm), Trichuris (whipworm), Ascaris (large roundworm), Ancylostoma/Necator (hookworms), Anisakiidae (fish roundworms),trematodes (flukes), Diphyllobothriidae (fish tapeworms), Taenia (pork/beef tapeworms), Hymenolepis/Dipylidium/Bertiella/Raillietina/Inermicapsifer (insect tapeworms), and Acanthocephala (thorny-headed worms).

In other compartments, visible worms can include immature or adult stages of Mammomonogamus (tracheolaryngeal roundworm), Thelazia (conjunctival roundworm), Gongylonema (buccal roundworm), Loa/Dirofilaria (eye worms), Onchocerca (river blindness roundworm), Lagochilascaris (cervical fistular roundworm), Dioctophyme (renal roundworm), Gnathostoma (larva migrans roundworm), Spirometra/Sparganum (larva migrans tapeworm), and Clinostomum (pharyngeal tapeworm).

This page is specific for identification of visible worms by naked eye only. Additional testing options exist for some organisms, refer to the PHO test information index for additional information.

Updates
This webpage has been updated to include background information, testing indications, specimen acceptance criteria, test methodology, performance and limitations, result interpretations, and expected turnaround times based on calendar days instead of business days.

*Uncontrolled print copy. Valid only on day of print: 17 Dec 2025.

Testing Indications

Identification for suspected whole worms or worm segments extracted from individuals suspected of a helminthic infection. In many instances, additional collection and testing methods should be performed as per the webpages.

Acceptance/Rejection Criteria

Accepted Specimens: Only specimens originating from human sources.
Rejected Specimens: Specimens submitted from animal (e.g. pets) or environmental (e.g. food) sources will be rejected.
Required Information: Specimens must be accompanied by relevant clinical or exposure information.
Incomplete Submissions: Specimens received without any clinical or exposure information may be rejected or result in delays of testing.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
Visible Worm - Identification	General Test Requisition	Suspected whole or segmented worm structure	N/A	Sterile container with normal or phosphate-buffered saline (0.85% NaCl) or 70-100% ethanol

Submission and Collection Notes

Add a few millilitres of sterile normal or phosphate-buffered saline (0.85% NaCl), or 70 to 100% ethanol inside the sterile container to fully submerge the suspected worm structure and prevent dehydration; if a transit delay beyond 24 hours of collection is expected, store worm in 70 to 100% ethanol to preserve structures.

Complete all fields of the requisition form.

Important: Specify which organism(s) are suspected on the requisition, if known.

Important: Provide complete clinical and exposure information on the requisition.

Label the specimen container(s) with the patient’s first and last name, date of collection, and one other unique identifier such as the patient’s date of birth or Health Card Number. For additional information see: Criteria for Acceptance of Patient Specimens. Failure to provide this information may result in rejection or testing delay.

Storage and Transport

Place specimen container in a biohazard bag and seal. Store at room temperature and ship to PHO’s laboratory within 48 hours of collection. All clinical specimens must be shipped in accordance to the Transportation of Dangerous Good Act.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Worm identification is performed daily from Monday to Friday at PHO’s Toronto laboratory site. Turnaround time is up to 5 calendar days from receipt at PHO.

Test Methods

Worm identification is primarily conducted through visual examination, supported by both stereomicroscopy and traditional light microscopy. These methods allow for detailed observation of morphological features that are critical for accurate identification.

Fragmented or degraded worm specimens may lack key feature, making identification difficult or inconclusive.

Interpretation

Microscopy:

Worm Identification	Interpretation
Parasite(s) found	The organism name(s) and stage(s) will be reported.
No parasites found	No evidence of parasitic worm structures(s). The structure is either not a parasite (e.g. vegetable, mucus, synthetic material, or environmental critter) or there was no identifiable structure.

Note for Taenia solium: assessment of the patient and their close contacts (e.g. household members) is recommended for potential cysticercosis co-infection.

Reporting

Results are reported to the physician, authorized health care provider (General O. Reg 45/22, s.18) or submitter as indicated on the requisition.