Canine Infections with Onchocerca lupi Nematodes, United States, 2011–2014 - Volume 21, Number 5—May 2015 - Emerging Infectious Disease journal - CDC
Volume 21, Number 5—May 2015
Canine Infections with Onchocerca lupi Nematodes, United States, 2011–2014
The number of human cases of zoonotic filariasis is increasing across industrialized countries (1). In particular, a major zoonotic potential has been recently recognized for Dirofilaria immitis and D. repens nematodes that infect dogs; both of these nematodes have been reported in cases of human dirofilariasis in the Western Hemisphere and the Old World (1,2).
After the first description of Onchocerca lupi nematodes in 1967 in a Caucasian wolf (Canis lupis cubanensis) from Georgia (former Union of Soviet Socialist Republics), this nematode has been recognized as the causative agent of canine and feline onchocercosis (3,4). In dogs, the infection occurs in an acute or chronic form characterized by ocular nodules that are often evident on the eyelids, conjunctiva, and sclera (3,5). However, if nematodes localize in the retrobulbar space of the eye, the infection may remain undetected (6). Nonetheless, in disease-endemic areas, O. lupimicrofilariae may be isolated from skin sediments of apparently healthy dogs (7). Thus, dogs with overt ocular infections might represent only a small portion of the population in which canine onchocercosis occurs in countries such as Hungary, Greece, Germany, and Portugal (3,7).
The role of O. lupi nematodes as an agent of infection in dogs in the United States has been suspected. However, nematodes were previously identified only as Onchocerca sp. in California and Utah (8,9) or as O. lienalis in Arizona (10). Recent etiologic delineation of O. lupi nematodes in dogs and cats in southwestern states (4,11,12) suggested involvement of this parasite in previous cases.
After the first case report of human ocular onchocercosis caused by O. lupi nematodes in Turkey (13), interest in this parasite has been renewed, and additional zoonotic cases have been identified in Turkey, Tunisia, and Iran (14). In addition, this parasite has been extracted from the cervical channel of a 22-month-old child in Arizona (12). Information on the epidemiology and life history of O. lupi nematodes is still minimal, and data on its distribution in the United States is limited to 6 case reports (4,11).
We report 8 cases of O. lupi nematode infection in dogs from Minnesota, New Mexico, Colorado, and Florida. We also compare cytochrome c oxidase subunit 1 (cox1) gene sequences from 2 nematodes with sequences from parasites in Europe to determine possible recent introduction of this filarioid from Europe to the United States.
Dr. Otranto is a professor in the Department of Veterinary Medicine, University of Bari, Valenzano, Italy. His research interests include biology and control of arthropod vector-borne diseases of animals and humans.
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Suggested citation for this article: Otranto D, Giannelli A, Latrofa MS, Dantas-Torres F, Scotty Trumble N, Chavkin M, et al. Canine infections withOnchocerca lupi nematodes, United States, 2011–2014. Emerg Infect Dis. 2015 May [date cited]. http://dx.doi.org/10.3201/eid2105.141812