|Year : 2014 | Volume
| Issue : 7 | Page : 822-824
Human ocular Thelaziasis in Karnataka
Prabhakar S Krishnachary1, Vijaykumar G Shankarappa2, Rajendra Rajarathnam1, Mahesh Shanthappa1
1 Department of Ophthalmology, J.S.S., Medical College and Hospital, JSS University, Mysore, Karnataka, India
2 Department of Microbiology, J.S.S., Medical College and Hospital, JSS University, Mysore, Karnataka, India
|Date of Submission||13-Mar-2011|
|Date of Acceptance||14-Apr-2014|
|Date of Web Publication||13-Aug-2014|
Prabhakar S Krishnachary
57, 8th cross, 4th main, Vinayaka Nagar, Mysore - 570 012, Karnataka
Source of Support: None, Conflict of Interest: None
Thelaziasis is an Arthropod-born disease of the eye and adnexa caused by Thelazia callipaeda, a nematode parasite transmitted by drosophilid flies to carnivores and humans. Because of its distribution mainly confined to South Asian countries and Russia, it is commonly known as Oriental Eye worm. It is often under-reported and not been given its due clinical importance. We report first case of human Thelaziasis from Hassan District, Karnataka. Five creamy-white, translucent worms were removed from the conjunctival sac of a 74-year-old male patient. Based on morphological characters, the worms were identified as nematodes belonging to the genus Thelazia and speciation was confirmed by CDC, Atlanta as callipaeda. Rarity of the disease and its ability to cause both extra and intraocular manifestations leading to ocular morbidity is the reason for presenting this case. From the available data, this is the first case report from Karnataka, India.
Keywords: Eye worm, human ocular Thelaziasis, human Thelaziasis, oriental eye worm, Thelazia callipaeda
|How to cite this article:|
Krishnachary PS, Shankarappa VG, Rajarathnam R, Shanthappa M. Human ocular Thelaziasis in Karnataka. Indian J Ophthalmol 2014;62:822-4
|How to cite this URL:|
Krishnachary PS, Shankarappa VG, Rajarathnam R, Shanthappa M. Human ocular Thelaziasis in Karnataka. Indian J Ophthalmol [serial online] 2014 [cited 2019 Oct 14];62:822-4. Available from: http://www.ijo.in/text.asp?2014/62/7/822/138183
Thelazia callipaeda was first described in 1910 from a Chinese dog. The first case of human Thelaziasis was reported in 1917,  wherein four worms were extracted from the eye of Coolie in Peiping, China and thereafter, a case of Human Thelaziasis (HT) in India was first reported from Yeroaud, Salem District in 1948.  Thelazia callipaeda (Spirurida, Thelaziidae) infects a range of definitive hosts, such as dogs, cats, foxes, rabbits, and humans; this spiruroid nematode is seen in the conjunctival sac, lacrimal gland, and lacrimal duct of these mammals.  The number of case reports of HT increased in several areas of Asia, where it occurs predominantly in rural communities with poor living and low socio-economic standards and mainly affects the elderly and children.  Ocular features of human Thelaziasis include excess lacrimation, irritation, conjunctivitis, keratitis, corneal ulcers, and ectropian.
Epidemiology and life cycle
Thelazia callipaeda (TC) and Thelazia californiensis are the two common nematode parasites known to cause human Thelaziasis . [Table 1] shows probable global data of ocular Thelaziasis. An infected person or carnivorous/bovine animal harbors the first stage larvae in the lacrimal secretions. Arthropod vectors feeding on such infected lacrimal secretions ingest these larvae, which undergo three molts inside the midgut of the vector in 2-3 weeks time and develop into infective third stage larvae. This stage is infective to humans. Third stage larvae are transmitted accidentally to another susceptible host by the vector when it feeds on such lacrimal secretions. The third stage larvae develops into adult form within 35 days in the eye of the infected person. 
| Case Report|| |
A 74-year-old Hindu farmer from Sakaleshpura taluk reported to Department of Ophthalmology with symptoms of foreign body sensation in his right eye for the last two days following a hit with the tail of cattle. The patient reportedly hails from a hilly region and rears the cattle in his farm house. On examination, eye was quiet, no conjunctival congestion, cornea and pupils were normal with visual acuity 20/20. Fundus examination revealed no abnormality. He was prescribed antibiotic eye drops and advised to come after a week. On 28 th July 2008, he returned with the same complaint. On examination, during the upper eyelid eversion, a white thread-like worm was seen near the lateral canthus. Slit lamp bio microscopic examination revealed four to five white, motile, translucent worms creeping in the superior fornix coming through a tunnel in the conjunctival sac. It was observed that two worms were already crawling on the corneal surface; five worms were removed with a plane forceps after instilling 4% Lignocain hydrochloride eye drops. The patient was observed for next three days for more worms, but no worms were found. After two years of follow up, there was no recurrence and the patient was symptomatically free.
| Materials and Methods|| |
The worms were transferred to a sterile normal saline container and were sent to microbiology department for further evaluation. The worms were identified as nematode parasites using inverted microscope, which showed sluggish motility, internal systems were clearly visible, and both the ends were straight, hook-like projections were appreciated [Figure 1], [Figure 2] and [Figure 3]. For further confirmation of the species, the worms and the microphotographs were sent to CDC Atlanta and confirmed as male worms of TC.
| Discussion|| |
Two species of the genus Thelazia, TC and Thelazia californiensis have been found in the human eye. TC is responsible for most of the cases of Human Ocular Thelaziasis (HOT) in Asia. Although these parasites commonly affect the anterior segment of the eye, it can cause severe damage to the posterior segment. A case of intraocular Thelaziasis with Rhegmatogenous retinal detachment  and intraocular inflammation involving vitreous causing visual disturbances and recovering the worm from human vitreous through pars plana vitrectomy  had been reported. Interestingly, the worm was discovered during intracapsular cataract surgery.  In HOT, the most common predisposing factors are unhealthy living conditions and the surrounding environment. Cattle rearing, contact with stray dogs, mountainous terrain, and rainy season make the humans vulnerable to ocular Thelaziasis. In the present case, cattle rearing was the predisposing factor, which correlates with the second case report of ocular Thelaziasis in 2008.  Conjunctival and cornel injuries, traumatic conjunctivitis facilitate the introduction of the larvae into the sub-conjunctival space and vitreous cavity.
The natural cycle of vector activity of ocular Thelaziasis has seasonal distribution, during (July-August) which period our patient had been reported. The main mode of transmission in this case was probably injury with the cattle tail and might be through contaminated towels. The towels being contaminated with cow dung containing deposited eggs/larvae of the worm and the same is used for wiping or rubbing the eyes after the injury is the possible mode of entry of eggs/larvae into the eyes. Although the treatment of canine infection by TC is with topical Organophosphates, 1% Moxidectin, 10% Imidacloprid is effective in mammals, mechanical removal of the parasite is the only curative treatment for HOT. In conclusion, HOT is a disease associated with very poor living conditions, low socio-economic status, and improper personal hygiene commonly seen among rural population.
Prevention of Thelaziasis is by protective measures like using bed nets at night, keeping the eyes, face and nose clean while sleeping to prevent the vectors, maintaining personal hygiene, keeping the surroundings clean, and creating public awareness about the disease.
| Acknowledgment|| |
We are thankful to the CDC, Atlanta, US. for identifying the worm and contributed to the preparation of the manuscript.
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[Figure 1], [Figure 2], [Figure 3]