Abstract
BackgroundAmong ocular vector-borne pathogens, Onchocerca volvulus, the agent of the so-called “river blindness”, affects about 37 million people globally. Other Onchocerca spp. have been sporadically reported as zoonotic agents. Cases of canine onchocerciasis caused by Onchocerca lupi are on the rise in the United States and Europe. Its zoonotic role has been suspected but only recently ascertained in a single case from Turkey. The present study provides further evidence on the occurrence of O. lupi infesting human eyes in two patients from Turkey (case 1) and Tunisia (case 2). The importance of obtaining a correct sample collection and preparation of nematodes infesting human eyes is highlighted.MethodsIn both cases the parasites were identified with morpho-anatomical characters at the gross examination, histological analysis and anatomical description and also molecularly in case 1.ResultsThe nematode from the first case was obviously O. lupi based on their morphology at the gross examination, histological analysis and anatomical description. In the second case, although the diagnostic cuticular characters were not completely developed, other features were congruent with the identification of O. lupi. Furthermore, the morphological identification was also molecularly confirmed in the Turkish case.ConclusionsThe results of this study suggest that O. lupi infestation is not an occasional finding but it should be considered in the differential diagnosis of other zoonotic helminths causing eye infestation in humans (e.g., D. immitis and Dirofilaria repens). Both cases came from areas where no cases of canine onchocerciasis were previously reported in the literature, suggesting that an in depth appraisal of the infestation in canine populations is necessary. Physicians and ophthalmologists are advised on how to preserve nematode samples recovered surgically, to allow a definitive, correct etiological diagnosis.
Highlights
Among ocular vector-borne pathogens, Onchocerca volvulus, the agent of the so-called “river blindness”, affects about 37 million people globally
The life cycles and the animal reservoir hosts for many of these species are still poorly known. This is the case of Onchocerca lupi, a parasite described in the periocular tissues of a Caucasian wolf (Canis lupus) in Georgia [8] that remained unknown for decades
The present study describes the occurrence of O. lupi infesting the human eye in two patients, from Turkey and from Tunisia where onchocerciasis caused by O. lupi has never been reported in dogs
Summary
Among ocular vector-borne pathogens, Onchocerca volvulus, the agent of the so-called “river blindness”, affects about 37 million people globally. Many species of helminths may cause human blindness in developed and developing countries, and some of them still represent a major threat for public health [1] This is the case of the so-called “river blindness” by Onchocerca volvulus (Spirurida, Onchocercidae), which affects about 37 million people [2] in East and West Africa as well as in central and South America [3]. In this case, visual impairment and blindness is mostly a direct effect of host immune response to microfilariae, which are released by female adult worms in the subcutaneous. Two ocular infestations by O. lupi have been suspected [23] and, recently, this species has been unambiguously identified in Turkey as causative agent of ocular infestation in a patient who exhibited clinical features similar to those of canine infestation [24]
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