Subconjunctival Dirofilaria repens Infestation: A Light and Scanning Electron Microscopy Study

Area of Science:

• Ophthalmology
• Parasitology
• Tropical Medicine

Background:

• Presents a rare case of subconjunctival Dirofilaria repens infestation in Northern Europe.
• Highlights the unusual occurrence of this parasitic nematode in a region where it is seldom encountered.

Purpose of the Study:

• To document and analyze a unique case of Dirofilaria repens subconjunctival infection.
• To contribute to the understanding of Dirofilaria repens as a rare cause of ocular infections in non-endemic areas.

Main Methods:

• A 61-year-old male patient presented with migratory supraorbital swelling and ocular symptoms.
• Incisional extraction of a nine cm long worm from the subconjunctival space.
• Histopathological and scanning electron microscopy analysis of the extracted nematode.

Main Results:

• The extracted worm measured nine cm, exhibiting characteristics of Dirofilaria repens, including a multi-layered cuticle, muscle layer, intestine, and reproductive organs.
• Microscopic examination confirmed it as a male Dirofilaria repens.
• The worm's structure indicated it was unable to mature or cause microfilariaemia in humans.

Conclusions:

• Dirofilaria repens is an uncommon accidental parasite in humans, rarely reported in Northern Europe.
• Ocular dirofilariasis should be considered in the differential diagnosis of nematode infections affecting the eye.
• Surgical excision is curative, and no further treatment is required as the parasite does not mature in human hosts.