1. Introduction
Onchocerca lupi (Nematoda: Onchocercidae) is an emerging, zoonotic parasite in North America and areas of the Old World (Cantey et al., 2016; Eberhard et al., 2013; Grácio, Richter, Komnenou, & Grácio, 2015; Otranto et al., 2015). Infection in dogs and cats are usually associated with episcleral and periocular tissues causing minor to severe ocular lesions, including conjunctivitis, third eyelid prolapse, exophthalmos, uveitis, and retinal detachment (McLean, Newkirk, & Adema, 2017; Otranto et al., 2015). However, the presentation of zoonotic onchocerciasis by O. lupi in humans may be variable according to the site of infection.
To date, there have been seven confirmed zoonotic onchocerciasis cases by O. lupi in the United States. Six of these cases involved children (Cantey et al., 2016; Eberhard et al., 2013). An additional medical concern is that three of these cases were associated with nodules at the cervical spinal cord; two of these cases had gravid adult female specimens, suggestive that these were patent infections. These North American human O. lupi infections have been reported from Arizona, New Mexico, and Texas. While, Arizona and New Mexico are considered endemic for this parasite, with multiple cases reported from companion animals, humans and wildlife (Cantey et al., 2016; McLean et al., 2017; Roe et al., 2020); the origin of the single human case in southern Texas remains uncertain. Thus far, all canine cases in North America reported outside of the presumed endemic southwestern United States (e.g., Minnesota, Florida, New York) have been associated with travel (Edelmann, Jager, Espinheira, & Ledbetter, 2018; Otranto et al., 2015; Verocai et al., 2016). Similarly, some European cases in dogs and humans have been linked to translocation or travel to endemic regions of the Mediterranean (Colella et al., 2018; Hodžić et al., 2018; Sandell, Skogen, Lier, & Pettersen, 2020).