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

Henrik A Melsom1, Jørgen A.L Kurtzhals2, Klaus Qvortrup 3, Ralph Bargum 4, Toke S Barfod 5, Morten la Cour 1, Steffen Heegaard *, 6
1 Department of Ophthalmology, Copenhagen University Hospital, Glostrup, Denmark
2 Centre for Medical Parasitology at Department of Clinical Microbiology, Copenhagen University Hospital (Rigshospitalet) and Department of International Health, Immunology and Microbiology, University of Copenhagen, Denmark
3 Department of Biomedical Sciences, University of Copenhagen, Denmark
4 Ralph Bargum’s Eye Clinic, Roskilde, Denmark
5 Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
6 Eye Pathology Section, Department of Neuroscience and Pharmacology, University of Copenhagen, Denmark

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© Melsom et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http: // which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Eye Pathology Section, University of Copenhagen, Denmark; Tel: + 45 35 32 60 70; Fax: + 45 35 32 60 80; E-mail:



To present a case of subconjunctival infestation with Dirofilaria repens which is very rare in Northern Europe.


A 61-year-old male presented with a swelling and redness of the left supraorbital region migrating to the eyelid and the left eyeball resulting in conjunctival injection, proptosis and diplopia. The patient underwent incisional extraction of a nine cm long worm, which was analysed histologically.


The worm was structureless, greyish-white in colour and measuring nine cm in length and 0.5 mm in diameter. Histopathological examination of the worm showed an outer thick, multi-layered cuticle with longitudinal ridges. Beneath the cuticle, a thick muscle layer was observed and internally the intestine and a single reproductive tube containing spermatozoa were noted. Scanning electron microscopy of the worm showed tapered ends, transverse striations and longitudinal ridges at the anterior end. The tail was relatively short with spirally coiled ridges indicating a male Dirofilaria repens.


Humans are an uncommon and accidental host of Dirofilaria repens which is rarely seen in Northern Europe but should be considered as a differential diagnosis to other nematode ocular infections. A travel history is helpful in diagnosing the potential involved organisms. No further treatment is necessary beyond surgical removal since this organism fails to mature and thereby does not cause microfilariaemia in humans.

Keywords: Conjunctiva, ocular, microscopy, Dirofilaria repens..