Onchocerca lupi Nematode in Cat, Portugal

To the Editor: Onchocerca lupi (Spirurida, Onchocercidae) is a nematode that infects the ocular tissues of dogs and humans. This filarioid remained almost unknown until recently, when it was reported in dogs from Europe and North America (1–3). O. lupi was also detected in 2 cats from the United States (4), which suggests that not only canids but also felids are suitable hosts for this little-known nematode. In addition, the zoonotic potential of O. lupi nematodes was demonstrated in human patients from Iran, Tunisia, Turkey, and the United States (3,5). Clinical signs of canine onchocercosis include conjunctivitis, exophthalmos, periorbital swelling, photophobia, discomfort, lacrimation, ocular discharge, subconjunctival granuloma, ulcerative keratitis, and anterior and posterior uveitis (1). Signs in cats are similar to those in dogs (4). After the first case of canine ocular onchocercosis was reported in the Algarve region in southern Portugal (6), a survey to detect microfilariae in apparently healthy dogs revealed an 8.3% prevalence of infection (7). Because no data regarding O. lupi nematode infection in cats from Europe are available, the aim of this study was to evaluate the infection’s occurrence in cats in Portugal, where canine infection has been previously reported (8). In October 2014, a total of 155 stray cats were sampled from Praia de Faro in the Algarve (37°0′29.4546′′N, 7°59′41.265′′W, altitude 9 meters). The sampling area is a small peninsula within an area characterized by a line of sand dunes formed by peninsulas and sandy islands that protect a vast area of marshland, canals, and islets from the Atlantic Ocean. All stray cats were captured under the scope of a trap, neuter, and return project. This study was