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   Table of Contents      
Year : 1996  |  Volume : 44  |  Issue : 2  |  Page : 99-101

Eye infestation with Thelazia species

1 Oil India Hospital, Duliajan - 786602, Assam, India
2 Tulane University School of Public Health and Tropical Medicine, New Orleans, USA

Correspondence Address:
J Mahanta
Regional Medical Research Centre N.E.Region (ICMR), P.B. 105, Dibrugarh, Assam 786001
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Source of Support: None, Conflict of Interest: None

PMID: 8916598

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How to cite this article:
Mahanta J, Alger J, Bordoloi P. Eye infestation with Thelazia species. Indian J Ophthalmol 1996;44:99-101

How to cite this URL:
Mahanta J, Alger J, Bordoloi P. Eye infestation with Thelazia species. Indian J Ophthalmol [serial online] 1996 [cited 2022 Nov 26];44:99-101. Available from: https://www.ijo.in/text.asp?1996/44/2/99/24597

Species of the genus Thelazia are nematodes that parasitize the conjunctival sac and lacrimal duct of a variety of mammals around the world. Most of the members of genus Thelazia occur in cattle, sheep, goat, water buffaloes, dogs, rabbits and deer.

Incidence in cattle varies from 5 - 42% in different countries.[1] Human infections have been reported with two species, T.callipaedaand T.californiensis. The former, a parasite of dogs, cats and rabbits, have been reported from different countries in Asia, including India, and Middle and Far East.[2],[3] The adult worms are cream colored, thread-like worms, measuring up to 2 cm in length. The presence of this worm in the eye causes excess lacrimation, as well as scarification and consequent opacification of the cornea and conjunctiva. Gravid female worms discharge embryonated eggs or larvae which, mixed with lacrimal secretions, are ingested by flies belonging to the genus Fannia and Musca. Once larvae develop to the infective stage, they migrate to the mouth parts of the fly and from there to a new host when the fly feeds on ocular secretions.[2],[4] Here we report a case in which such a worm was recovered during the course of a surgical procedure for removal of a cataract. A review of the literature available to us, suggests that thelaziasis has been rarely reported from humans in India.

  Case report Top

A 70-year old male, Hindu farmer, otherwise healthy, reported to Oil India Hospital, Duliajan, Assam, with progressive diminution of vision for the last 10 years with occasional irritation and watering from the right eye. The patient did not give any history of pain or of seeing any floating objects in field of vision during this period. On examination he was found to have mature cataracts in both eyes; intraocular pressure was 17.3 mm of Hg in both eyes. Visual acuity was hand movements, and accurate projection of light. Orbit, lacrimal system, cornea, conjunctivae, iris and anterior chamber appeared normal on clinical examination in both eyes. Opaque lenses prevented optical examination of fundus at the time of admission. As a hospitalized patient, routine investigations of blood, stool and urine were carried out. Some of the relevant findings were: total leukocyte count of 9300 per ul of blood with 11% of eosinophils; erythrocyte sedimentation rate was 60 mm at one hour (Westergreen). Pre operative examination and irrigation of lacrimal sac did not reveal any abnormality. The results of other biochemical and hematologic tests, performed after surgical procedure, were within normal values. Intracapsular cataract extraction (ICCE) with peripheral button hole iridectomy (PBI) was performed in the right eye. At operation, after incision of the conjunctiva and sclera during the process of lens extraction, it appeared that a thread-like worm came out through the incision to the surgical field. It is more likely however that the worm was in fact in the conjunctival sac. The post-operative period was uneventful. The aphakic eye was examined a week after the operation to search for any other worm residing in the ocular tissues including the fundus. Vitreous and fundus were found to be normal.

  The Worm Top

The worm was fixed in formalin and cleared in glycerine to render it transparent. Grossly, it was creamy-white in color, thread-like in shape and measured 8.84 mm in length with a maximum diameter of 0.34 mm. Microscopical examination revealed that the worm was an immature male. The anterior end was tapered and the bluntly rounded posterior end was recurved ventrally ([Figure - 1]A and [Figure - 1]D). The body surface was covered by a heavily striated cuticle. The anterior extremity bore a conspicuous buccal capsule divided in festoons. The esophagus was essentially muscular, 0.47 mm long, and there was a conspicuous nerve ring ([Figure - 1]B and [Figure - 1]C). The male reproductive tube recurved distally, terminated near the esophago-intestinal junction. There were numerous paired perianal papillae surrounding the cloacal opening and paired unequal spicules. The right spicule was short and measured 0.14 mm, the left was slender and very long measuring 0.94 mm, [Figure:1D]. Overall, the morphologic features of the worm were consistent with the genus Thelazia. A species identification was not possible without examination of the female worm and additional male specimens which, of course, were not available.

  Discussion Top

T.callipaeda and T.californiensis are usually reported from man and are the common parasite of dogs, cats, sheep, rabbit and deer. The patient being a rural farmer has a fair chance of acquiring the parasite from the pets like dogs, cat and sheep. However, survey in animals of this locality is yet to be done.

Conjunctivitis, pain in the eye and excess lacrimation are common with T.callipaeda and T.californiensis infection. The case under discussion had only occasional irritation and watering from the affected eye. Though duration and intensity is uncertain yet this can be attributed to Thelazia infestation. An intraocular site for the worm was considered but could not be absolutely documented. It most likely escaped from the conjunctival sac in the course of the surgical procedure. Thelazia spp. often infests lacrimal system in animals as well as human, yet in absence of preoperative abnormality in lacrimal sac and duct system during clinical examination and syringing, the possibility of the worm residing in it and coming out during operation is remote in this case.

Thelazia infection is successfully treated with lavimasole and ivermectin in animals. In human beings removal of the worm from the eye is often sufficient. Moreover, in view of negligible preoperative symptoms and absence of any evidence of parasite in the ocular tissue after operation, no specific treatment was given in this case for Thelazia. However the case was followed for a year and there were no symptoms pertaining to the nematode.

A review of the literature indicates that human cases reported from India are far less numerous than initially thought. One case reported in 1948, from Salem District, was probably the first case from India.[5] Two additional cases were reported from Manipur.[6] The purpose of this report is to alert the medical community about the condition and its causative agent.

  Acknowledgement Top

The authors express their gratitude to Dr. Thomas C. Orihel, Tulane University Department of Tropical Medicine, for his assistance in identification of the worm and the review of the manuscript.

  References Top

Soulsby EJL. Helminths, Arthropods and protozoa of domestic animals, 7th edition, London,Bailliere Tindall. 289-290,1982.  Back to cited text no. 1
Beaver PC, Jung R and Cupp EW. Clinical Parasitology. Lea and Febiger; Philadelphia, 1984.  Back to cited text no. 2
Orihel TC and Ash LR. Parasites in Human Tissues. ASCP Press; Chicago, Illinois, 1995.  Back to cited text no. 3
Levine N. Nematode Parasites of Domestic Animals and of Man. Burgess Publishing Company; Minneapolis, Minnesota, 1980.  Back to cited text no. 4
Friedmann M. Thelazia callipaeda, the "Oriental Eye Worm". Antiseptic 45:620-626,1948.  Back to cited text no. 5
Singh TS and Singh KN. Thelaziasis: report of two cases. Br J Ophthalmol 77:528-529,1993.  Back to cited text no. 6


  [Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]


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