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).