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Video Report Removal of Dirofilarial worm from the subconjunctival space Debjoy Mallik (1), Suman Alexander (2)1Whipps Cross University Hospital, London, United Kingdom; 2CBM Ophthalmic Institute, Angamaly, Kerala, South India
Correspondence: Dr Debjoy Mallik Date of acceptance: November 1, 2005 |
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Dirofilariasis, a zoonotic disease, is uncommon in humans and has been known to involve the periocular tissues. Shown here is a 68 year old female resident of the Ernakulam district in the south Indian state of Kerala who presented with irritation of the right eye of 3 days duration, caused by a large worm moving in the temporal subconjunctival space. After application of topical anaesthesia, a small limbal peritomy was done to expose the mobile worm, which was then removed using forceps. |
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Note: This video is best viewed in Quicktime Introduction Dirofilariasis, a zoonotic disease, is uncommon in humans and has been known to involve the periocular tissues. To our knowledge there are no video reports of a live Dirofilarial worm being removed from the subconjunctival space. In this report we present rare video footage of a live Dirofilarial worm being removed from the subconjunctival space and discuss how an uncontrolled canine reservoir of infection can pose a public health hazard.
A 68 year old female patient who was a resident of the Ernakulam district in the south Indian state of Kerala presented with a vague irritation of the right eye of 3 days duration. She had no visual complaints at the time of presentation. On examination she was found to have a best corrected visual acuity of 6/18 in both eyes, further improvement in visual acuity being limited by the presence of a senile immature cataract in both eyes. The right eye had a grossly congested and chemosed conjunctiva and slit lamp examination revealed a large worm moving in the subconjunctival space just temporal to the 9 o’clock limbus. The anterior segment and fundus of the right eye were otherwise unremarkable. The left eye was within normal limits apart from the presence of an immature cataract. The patient’s blood counts revealed no eosinophilia and stool examination revealed no ova, parasites or cysts. After application of a topical anaesthetic agent, a wire speculum was applied to hold the eyelids apart (see video: fast connectionor dial up connection). A local peritomy was gently done at the 9 O'clock limbus and the conjunctival flap was retracted to expose the moving worm. The worm was then removed using a pair of forceps. The peritomy was closed with 6-0 vicryl sutures following the procedure. The patient and was put on a short course of topical steroids and antibiotics to reduce the conjunctival inflammation and had no further complaints following surgery. The worm was 105 mm in length and parasitological study revealed it to be a sexually immature female Dirofilaria repens worm.
Comment Dirofilariasis is believed to be acquired from a canine reservoir of infection through a mosquito vector as described in our earlier report.[1] It is important to distinguish Dirofilaria worms from Dipetalonema, which is also commonly endemic in dogs and is known to affect the subconjunctival space. While Dipetalonema stains evenly with acid phosphatase, Dirofilaria concentrates the acid phosphatase in two regions. Female Dipetalonema worms are reported to grow to a length of 17–32 mm on an average while males are much smaller.[2] The female Dirofilarial worm isolated from our case was 105 mm in length. It is interesting to note that a recent study conducted at a district veterinary centre at Trichur in Kerala using immunohistochemical techniques for species identification identified D repens as the only species of microfilaria infecting the local dog population, incidence of infection being the highest during the summer months.[3] Kerala's backwaters provide an ideal breeding ground for possible mosquito vectors for the transmission of dirofilariasis from its canine reservoir to humans. There have been no entomological studies so far to identify the species of mosquito acting as vectors for the microfilariae of Dirofilaria repens in Kerala. This is important as it could help formulate strategies to isolate and eliminate the offending vector. It is also important to take measures to control the reservoir of infection in the canine population as it poses a health hazard to humans. Humans represent a dead end in the life cycle of Dirofilaria and human-to-human transmission is not known to occur. As it is a self-limiting condition, the definitive treatment is surgical removal of the worm.
Competing Interests Statement The authors declare that they have no competing interests in this video report.
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