Subconjunctival human dirofilariasis by Dirofilaria repens in the Mediterranean Basin

Abstract

Purpose: Human dirofilariasis cases have increased in Europe for the last few decades. We document an autochthonous case of dirofilariasis infection in the subconjunctival space of a 60-year-old Spanish man.

Observations: The patient presented with pain in his right eye, which was diagnosed as epi-scleritis. In spite of the treatment administered, no improvement was reported. An external exam showed conjunctival congestion on the temporal part of the right eye bulbar conjunctiva. The anterior chamber showed no flare or cells in both eyes and dilated fundus exam was normal. Nevertheless, a long whitish vermiform mobile mass was detected under the conjunctiva in the temporal part of the right eye. The worm was surgically removed and diagnosed morphologically and also molecularly as Dirofilaria repens. This species uses dogs and wild canids as definitive hosts and principal reservoirs, while mosquito species are transmitters. Humans act as accidental hosts, and clinical manifestations depend on the location of the worm in the organs and tissues.

Conclusions and importance: The correct diagnosis and control of subcutaneous/ocular dirofilariasis by D. repens require several professionals under the One Health approach to deal with this zoonotic disease, which poses a serious public health problem, at least in the Mediterranean Basin.

Keywords: Dirofilaria repens; Human infection; Subconjunctival dirofilariasis.

Fig. 1

(A) Worm of Dirofilaria repens removed from the subconjunctiva of the patient eye; (B) entire worm isolated in the present case; (C) aspect of the ridges of the cuticle under an optical microscope; (D) Multiplex PCR amplification of the DNA extracted from the worm surgically removed from the patient. Lane 1: sample obtained from the worm removed from the patient; lane 2: D. immitis positive control (500 pb and 204 pb); lane 3: D. repens positive control (500 pb and 327 pb); lane 4: negative control. MK: molecular marker, 100–1000 pb.