Abstract
Purpose: To present an interesting case of intraocular Linguatula serrata in a 5-year-old boy. Design: Case report.
Methods: Visual acuity testing, biomicroscopic slit-lamp examination, and indirect ophthalmoscopy were performed on a 5-year-old boy with a progressively enlarging white lesion in the anterior chamber of the right eye.
Results: The worm was found in the anterior chamber, attached firmly to the peripheral iris with free-floating tail. The living worm, which grew progressively over 2 months, caused a mild anterior chamber reaction with marginally raised intraocular pressure. The worm was removed surgically in toto. This is the first documentation of human ocular pentastomiasis in India.
Conclusions: An adult worm in the anterior chamber is apparently rare and can present even with a quiet eye. Surgical removal is essential. However, visual prognosis is good.
Linguatula serrata, the tongue worm is a cosmopolitan zoonotic endoparasite. Human infection is very rare. Only a few documented reports exist in literature, where man acts as an intermediate host. This article reports the presence of an adult worm in the anterior chamber of the eye in a 5-year-old boy.
CASE REPORT
We examined a 5-year-old boy from Jharkhand, India who complained of diminution of vision and a gradually enlarging white dot in the right eye since 2 months. His diet was nonvegetarian and he was in contact with a pet dog. His best-corrected vision was 6/9, N18 and 6/6, N6 in the right and left eyes, respectively. The anterior segment of the right eye showed a brown and white, nonmobile worm in the anterior chamber, 6 mm in length and 2 mm in width. The head end was firmly attached to the peripheral iris surface in the nasal angle, which was confirmed by gonioscopy, while the tail end was free-floating, reaching up to the center of pupil and touching the endothelium. Grade I (SUN working group classification) anterior chamber cells and a few pigment clumps on the anterior lens capsule were noted. The lens and anterior vitreous cavity were clear. The left eye was within normal limits. The intraocular pressure was 19 and 14 mm Hg in the right and left eye, respectively. Fundus examination in both eyes was normal. The patient had a mild fever with nonproductive cough 2 weeks prior to his examination. Blood investigations showed raised ESR (48 mm) and eosinophilia (8%); peripheral smear was within normal limits. Urine and stool examinations were within normal limits. A chest X-ray and a CT scan of the brain did not reveal any abnormality. Surgical removal of the worm was planned and the patient was started on oral and topical steroids and oral albendazole. Surgery was done under general anesthesia. In view of the mobile tail, pilocarpine was injected to constrict the pupil, but it failed. The worm was separated from the iris surface by viscoelastic injection and detached by using an iris hook. The worm was visco-expressed in toto through a clear corneal incision, without damaging the endothelium or lens. Indirect ophthalmoscopy was performed to rule out any retinal lesion.
Morphological evaluation of the worm was conducted at the Department of Veterinary Parasitology, Madras Veterinary College, Chennai, India. The worm was 6 mm anteroposterly, 2 mm lateral width, and 1.5 mm dorsoventrally. The worm was tongue shaped, slightly convex dorsally, and flattened ventrally, covered with thin whitish cuticle with deep ringed. The anterior end had two pairs of hooks on either side of oral aperture. Due to the above morphology we identified it as a female Linguatula serrata worm.
DISCUSSION
The worm Linguatula serrata is a cosmopolitan zoonotic parasite, belonging to the phylum Pentastomida. They inhabit the respiratory systems of vertebrates. In normal habitat the body is differentiated into an anterior head region and a long posterior trunk. The females (80–120 mm) are larger than the males (18–20 mm). The worm is tongue shaped, slightly convex dorsally, and flattened ventrally, covered with thin whitish cuticle, deeply ringed. The cuticle is thin and translucent and in living specimens, the body organs are clearly visible. The anterior end had two pairs of strong hooks on either side of an elongated oral aperture.Citation6
The adult worm is usually found in the nasal passages of dogs and they feed on blood and fluids. The eggs exit the host in nasal secretions or, if swallowed, with faeces. When ingested by intermediate hosts like sheep or goats, the larvae hatch in the small intestine, penetrate the intestinal wall, migrate through blood vessels, and lodge themselves in tissues, particularly in lungs, liver, and lymph nodes, and develop into the nymphal stage. Humans may also become accidental intermediate hosts.Citation1 When eaten by a definitive host, infective nymphs either attach in the upper digestive tract or quickly travel from the stomach, reaching the nasopharynx, and develop into adult worms.Citation2,Citation5
Infection in humans with the adult form of Linguatula serrata is called Halzoun syndrome, which is due to blockage of nasal pathways.Citation3 In this case, the adult worm was seen intraocular, an unusual location and the first of its kind to be reported in the literature, probably by hematogenous migration of larval form. The presence of the adult worm or larval form in the anterior chamber can produce severe reaction, secondary glaucoma, and subluxation of lens—all of which have been reported earlier in the literature.Citation4 However, in our case, the eye was quiet.
Since surgical removal of worm was essential, our aim was to prevent postoperative reaction and to remove the worm in toto. Oral steroids were started a week before the surgery. The worm was firmly attached to the peripheral iris surface. Viscoelatic was injected to create a plane and the head was detached with an iris hook. Once detached, the worm was visco-expressed through the limbal incision. Postoperatively, the steroids were tapered. Six weeks later, the eye was quiet with 6/6, N6 vision.
TABLE 1 Scientific classification.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
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- EJL Soulsby, 1968. Helminths, Arthropods and Protozoa of Domesticated Animals, 6th ed. ELBS & Bailliere, Tindall & Cassell; 1968: 518–519.