Ocular dirofilariasis in Dubai, UAE.

A rare occurrence of ocular subconjunctival dirofilariasis in a 53-year-old healthy Indian male working in Dubai, UAE presenting with an acute red eye is reported. Surgical excision under topical anesthesia was carried out uneventfully in the outpatient clinic. The live worm removed from the subconjunctival space was identified as Dirofilaria repens on the basis of microscopic examination and histopathology. Surgical excision of subconjunctival dirofilariasis is safe in an outpatient setting and curative precluding the need for further systemic antihelminthics.

Dirofilariasis is a well-documented parasitic infection that may present as zoonotic infestation in humans.1 The microfilariae are accidentally transmitted to humans by Culex and Aedes mosquitoes. Man is a dead end host for the parasite and systemic involvement may be subcutaneous,2,3 pulmonary4 or generalized.5 Ophthalmic involvement may be periorbital,6-8 subconjunctival,9,10 sub-tenons11 or intraocular.12 Such lesions are usually associated with moderate to severe inflammation. Subcutaneous dirofilariasis over the abdomen was reported in Kuwait in 1994.13 To our knowledge, ocular dirofilariasis in the Arabian Peninsula is hitherto unreported and this is the first report of subconjunctival dirofilariasis in the Middle Eastern region.

Case Report

A 53-year-old Indian male employed in Dubai, UAE presented with a sudden onset of foreign body sensation in his left eye while at work for which he used an eyewash from the first-aid kit. This was followed by an acute bout of pain, redness and watering which was attributed to the eyewash being past the expiry date. The patient was referred by the treating emergency physician with a suspected bleb and to rule out chemical conjunctivitis. There was no history of injury, allergy or of recent travel. The patient did have a history of longstanding generalized episodic itching over six to nine months with localized subcutaneous swelling lasting for a few seconds to five minutes and affecting the hands, chest and neck.

Slit-lamp examination revealed conjunctival chemosis with a live worm in the subconjunctival space adjacent to the nasal limbus, responding to light and to gentle pressure over the conjunctiva with a cotton swab. The head end was coiled up at the nasal limbus at the 9 O′clock meridian [Fig. 1] while the tail end was coiled up at the temporal limbus at the 3 O′clock meridian giving the appearance of two separate worms. Rest of the ocular examination was unremarkable.

Figure 1

Clinical photograph depicting nasal chemosis

The worm was immobilized using topical lignocaine. A nick was made in the conjunctiva and the live worm was removed in toto using a blunt forceps [Fig. 2]. It measured approximately 11 cm in length. Histopathological examination carried out elsewhere at an overseas parasitology laboratory reported an adult female Dirofilaria repens [Fig. 3].

Figure 2

Gross appearance of worm

Figure 3

Microscopic appearance of worm

Complete blood picture and erythrocyte sedimentation rate (ESR) were within normal limits with no evidence of eosinophilia. Peripheral smear was unremarkable and no microfilaremia was detectable.

Symptoms resolved promptly following surgical removal with no ocular or systemic recurrences over a follow-up of one year.

Discussion

Dirofilariasis is a zoonotic illness, rarely seen in humans. The worms may be subcutaneous as Dirofilaria repens or may be deep-seated as Dirofilaria imitis which frequently results in pulmonary dirofilariasis. Dirofilaria repens is a natural parasite of carnivorous animals, primarily dogs, foxes and cats.

Dirofilariasis is often reported from European countries surrounding the Mediterranean region. A review of world literature14,15 reports over 780 documented cases in diverse geographical locations with Italy, Sri Lanka and some countries of the former Soviet Union being the most affected areas.

Dirofilariasis has been reported to be associated with travel to ′foreign′ lands.2,3 A history of migratory swellings and travel to endemic areas should arouse the suspicion of its possible diagnosis.16 In India, dirofilariasis is predominantly reported in published literature in southern India with reports from Kerala,17 Karnataka10 and Tamil Nadu.11 Being an inhabitant of Kerala and working in Dubai, in this patient it is unclear if he contracted the infection from his bi-annual visits back to his home country, through the frequently imported African machinery as a part of his occupation or locally in Dubai itself which is not a known endemic area.

Migratory subcutaneous dirofilariasis2 has been frequently reported, however, simultaneous ocular involvement has not been documented. While it has not been clinically documented, this patient did have a past history suggestive of a subcutaneous involvement six to nine months prior to the ocular manifestations.

Surgical removal of the worm is curative18-20 and a technically simple procedure. We were able to carry out this procedure uneventfully in an outpatient setting minor procedure room under topical anesthesia with lignocaine. Alternatively, the live worm could have been paralysed using topical pilocarpine.

Identification was done using standard histopathological methods by diagnostic evaluation of microscopic cross-sections and macroscopic characteristics of the worm. Dirofilarial worms are identified by their thick laminated cuticle, broad lateral chords and large muscle cells. Accurate species identification is best done by examination of mature worms. Direct polymerase chain reaction (PCR) protocols may aid in identification in instances of tissue degeneration or poor specimen preservation practices and may have a clinical application as a routine diagnostic aid.21

In conclusion, we report the first incidence of a live subconjunctival dirofilariasis in the Arabian Peninsula. Surgical removal and management along previously described guidelines led to satisfactory resolution of symptoms with a good clinical outcome.