Atypical diagnostic consideration - from a GI tract parasitic infection to unusual onsite contamination

Debasish Biswal1, Nishant Verma1, Bijay Ranjan Mirdha1

Patient description

A 60-year-old male, presented to the emergency department with complaints of dizziness, faecal incontinence and passage of black coloured watery stool during morning walk on the same day. He was treated and discharged from hospital after 48 hours.

Follow up

While at home, he found some worms on the faecal soiled clothes worn on the day of complaints, that were kept at home unwashed. These worms were of similar type and were sent for identification to the parasitology laboratory.

The worms were yellowish white, wriggling and measuring about 11 ̶ 13 mm in length. Identification was carried out using hydroxide clearing method [1]. One of the worms was taken, placed in a beaker containing hot water (80°C) for 30 seconds to prevent shrinkage. Thereafter, it was preserved in a small glass bottle containing 70% ethanol, following which, kept in a glass Petri dish containing 10% potassium hydroxide solution for one day. Subsequently, the specimens were washed with distilled water, placed in another Petri dish containing a mixture of 35% ethanol and 1% glacial acetic acid for 30 minutes followed by serial dehydration with 50%, 70%, 80%, 95% and absolute ethanol for 30 minutes in each. Upon microscopic examination of DPX (a mixture of distyrene, a plasticizer, and xylene) mounted slides, anteriorly hook like structure (Fig. 1) and posterior spiracles were seen (Fig. 2). The worm was identified as larva of the housefly Musca domestica.


Considering the possibility of intestinal myiasis, the patient underwent colonoscopy and upper GI endoscopy. Investigating for intestinal parasitosis, no significant results were observed.


[1] Adams ZJO, Hall MJR. Methods used for the killing and preservation of blowfly larvae, and their effect on post-mortem larval length. Forensic Sci Int 2003; 138:50-61. DOI: 10.1016/j.forsciint.2003.08.010

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Figure 1. Anterior end of larva (400× magnification): cylindrical tapering end with a hook like structure.
[please click on the image to enlarge]

Figure 2. Posterior spiracle of larva (400× magnification): each spiracle is outlined by a thick dark band, with 3 sinuous shaped slits surrounding a button located towards the inner edge.
[please click on the image to enlarge]

Conflict of interest: none declared.

Authors’ affiliations:
1 Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India.

Corresponding author:
Bijay Ranjan Mirdha
Professor, Department of Microbiology
All India Institute of Medical Sciences
New Delhi
e-mail: mirdhabr@hotmail.com

To cite this article: Biswal D, Verma N, Mirdha BR. Atypical diagnostic consideration - from a GI tract parasitic infection to unusual onsite contamination. World J Med Images Videos Cases 2022; 8:e93-96.

Submitted for publication: 15 August 2022
Accepted for publication: 2 October 2022
Published on: 29 December 2022

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