Case report: First evidence of human zoonotic infection by Onchocerca lupi (Spirurida, Onchocercidae)

Abstract

In the past decades, cases of canine ocular onchocercosis have been reported worldwide, particularly in the United States and Europe. Onchocerca lupi, originally described from a wolf, has been implicated in some of these cases, and its zoonotic role has been hypothesized on the basis of the reexamination of two cases of human ocular onchocerciasis. In the present study, we describe, for the first time, the occurrence of O. lupi in the subconjunctival region of the human eye in a patient from Turkey. The nematode was identified as O. lupi based on its morphology and molecular phylogenetic analysis of partial cox1 and 12S ribosomal DNA genes. The results suggest that O. lupi should be considered in the differential diagnosis of other eye parasitic infections in humans. The role of dogs as natural hosts of O. lupi and the vectors of this zoonotic parasite need to be investigated.

Figure 1.

Ocular onchocerciasis. Episcleral hyperemia and subconjunctival mass on the superonasal quadrant of bulbar conjunctiva. This figure appears in color at www.ajtmh.org.

Figure 2.

Female O. lupi. (A) Macroscopic view of the nematode removed from the subconjunctival mass, with an arrow pointing to the damaged end (Scale bar = 1,000 µm). (B) Thick and multilayered cuticle bearing prominent annular ridges (white arrow) on the external surface and typical transverse striae (black arrow) in the internal layer (Scale bar = 60 µm). This figure appears in color at www.ajtmh.org.

Figure 3.

Phylogeny of filarioid onchocercidae based on cox1 gene sequences. Numbers in parentheses are Genbank accession numbers.