Ascaris lumbricoides is the largest

Ascaris lumbricoides is the largest intestinal nematode parasitising man. Man is the only definitive host of Ascaris lumbricoides. This parasite is unique in that it passes its entire life cycle in one host. Continuance of the species is ensured by transference from one host to another. The female is capable of laying both fertilized and unfertilized eggs. The mature female worm has an enormous egglaying capacity, liberating about 200,000 eggs daily.

The various stages of the worm's life cycle include: (1) eggs in faeces, (2) development in soil, (3) infection by ingestion and liberation of larva, (4) migration - small intestine - portal circulation - liver - right heart - pulmonary circulation - lung alveoli, (5) re-entry into the stomach and the small intestine from the lung alveoli, and (6) sexual maturity and egg liberation. During migration, the Ascaris worm may accidentally enter the respiratory passage, lumen of the appendix, biliary passage and liver.

The eggs of Ascaris behave like an inert material. The larva produces an irritant fluid due to the presence of Ascarase, resulting in allergic manifestation. The body fluid of Ascaris lumbricoides, when absorbed, is toxic and may damage the tissues. The worm is known to cause subconjunctival mass, granulomatous iridocyclitis, choroiditis (macular or paramacular), recurrent vitreous haemorrhage, periphelebitis, papilloedema, chronic dacryocystitis and invasion into the subretinal space.[1]

Ascaris larvae do not normally develop in the eye, as shown by animal experiments with intraocular injection of Ascaris ova. In this boy, the possible way the worm could have reached the eye is, as described above during stage five, by the larvae crawling up the bronchi, trachea and the nasopharynx, and getting regurgitated into the nasolacrimal duct and then migrating out into the conjunctival sac through the lacrimal punctum. Our case is similar to the two cases described in the literature. [2,3]

Management of ascariasis includes treatment with either mebendazole (100 mg twice a day for 3 days) or pyrantel pamoate (11mg/kg/in single dose). For ectopic infections without systemic involvement, as in our case, surgical removal is the only therapy recommended in the literature.