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Infections with Onchocerca lupi nematodes are diagnosed sporadically in the United States. We report 8 cases of canine onchocercosis in Minnesota, New Mexico, Colorado, and Florida. Identification of 1 cytochrome c oxidase subunit 1 gene haplotype identical to 1 of 5 from Europe suggests recent introduction of this nematode into the United States.

In southern California, ocular infections caused by Onchocerca lupi were diagnosed in 3 dogs (1 in 2006, 2 in 2012). The infectious agent was confirmed through morphologic analysis of fixed parasites in tissues and by PCR and sequencing of amplicons derived from 2 mitochondrially encoded genes and 1 nuclear-encoded gene. A nested PCR based on the sequence of the cytochrome oxidase subunit 1 gene of the parasite was developed and used to screen Simulium black flies collected from southern California for O. lupi DNA. Six (2.8%; 95% CI 0.6%-5.0%) of 213 black flies contained O. lupi DNA. Partial mitochondrial16S rRNA gene sequences from the infected flies matched sequences derived from black fly larvae cytotaxonomically identified as Simulium tribulatum. These data implicate S. tribulatum flies as a putative vector for O. lupi in southern California.

Background: Onchocerca lupi, a filarioid of zoonotic concern, infects dogs and cats causing ocular lesions of different degrees, from minor to severe. However, infected animals do not always display overt clinical signs, rendering the diagnosis of the infection obscure to the majority of veterinarians. Canine onchocercosis has been reported in the Old World and the information on its occurrence in the United States, as well as its pathogenesis and clinical management is still meagre. This study reports on the largest case series of O. lupi infection from the United States and reviews previous cases of canine onchocercosis in this country., Methods: Information on the clinical history of a series of eight cases of O. lupi infection in dogs diagnosed in Minnesota, New Mexico, Colorado and Florida, from 2011 to 2014, was obtained from clinical records provided the veterinary practitioners. Nematodes were morphologically identified at species level and genetically analyzed., Results: All dogs displayed a similar clinical presentation, including subconjunctival and episcleral nodules, which were surgically removed. Each dog was subjected to post-operative therapy. Whitish filaria-like parasites were morphologically and molecularly identified as O. lupi., Conclusions: This study confirms that O. lupi is endemic in the United States, indicating that the distribution of the infection is probably wider than previously thought. With effect, further studies are urgently needed in order to improve the diagnosis and to assess the efficacy of therapeutic protocols, targeting the parasite itself and/or its endosymbionts.

A 22-month-old girl presented with neck pain and stiffness and magnetic resonance imaging showed an extradural mass extending from C2 through the C4 level with moderate to severe compression of the cord. A left unilateral C2-C4 laminectomy was performed revealing an extradural rubbery tumor; a small biopsy was obtained. Examination of stained tissue revealed the presence of a parasitic worm that was identified as a gravid female Onchocerca lupi. A magnetic resonance imaging at 7 weeks follow-up showed a significantly decreased size of the enhancing lesion and the patient's symptoms gradually resolved. This is the first report of zoonotic O. lupi in the United States. The parasite has been reported in dogs and cats in the western United States, and from people in four cases reported from Europe. A great deal more needs to be learned, including full host range and geographic distribution, before we fully understand O. lupi infections in animals and man.

A long, slender filarial nematode was removed from the left anterior chamber of a resident of Oregon after several days of pain and blurred vision. The worm was identified as an Onchocerca, but it could not be further identified. This worm is the third zoonotic Onchocerca removed from the anterior chamber and the second case reported from the United States. Cases of zoonotic onchocerciasis continue to garner attention, and those cases affecting the eye are of particular interest.

Objective: To report the case of a 65-year-old male patient from western Hungary who presented with rapidly progressive peripheral visual field (VF) loss and the sensation of an actively moving object in his central VF., Design: Interventional case report. METHOD/INTERVENTION: A live nematode was removed from the anterior vitreous cavity by pars plana vitrectomy., Results: The worm was successfully removed surgically, and the patient had an uneventful recovery. The nematode was identified as an immature filaria, most likely a member of the genus Onchocerca., Conclusions: Only 3 previous reports exist of human infection of the eye caused by zoonotic Onchocerca, 2 involving the subconjunctiva and 1 the cornea. Although rare, zoonotic onchocercal infection of the eye must be considered a differential diagnostic entity even in temperate climates.

Background: The study of Onchocerca volvulus has been limited by its host range, with only humans and non-human primates shown to be susceptible to the full life cycle infection. Small animal models that support the development of adult parasites have not been identified. Methodology/Principal findings: We hypothesized that highly immunodeficient NSG mice would support the survival and maturation of O. volvulus and alteration of the host microenvironment through the addition of various human cells and tissues would further enhance the level of parasite maturation. NSG mice were humanized with: (1) umbilical cord derived CD34+ stem cells, (2) fetal derived liver, thymus and CD34+ stem cells or (3) primary human skeletal muscle cells. NSG and humanized NSG mice were infected with 100 O. volvulus infective larvae (L3) for 4 to 12 weeks. When necropsies of infected animals were performed, it was observed that parasites survived and developed throughout the infection time course. In each of the different humanized mouse models, worms matured from L3 to advanced fourth stage larvae, with both male and female organ development. In addition, worms increased in length by up to 4-fold. Serum and urine, collected from humanized mice for identification of potential biomarkers of infection, allowed for the identification of 10 O. volvulus-derived proteins found specifically in either the urine or the serum of the humanized O. volvulus-infected NSG mice. Conclusions/Significance: The newly identified mouse models for onchocerciasis will enable the development of O. volvulus specific biomarkers, screening for new therapeutic approaches and potentially studying the human immune response to infection with O. volvulus. [ABSTRACT FROM AUTHOR]

Since 1991, 53 cases of canine ocular onchocerciasis have been reported in the literature worldwide, 43 of these were from Greece, five from Hungary, and five from the western United States. Information on the histopathologic features of canine ocular onchocerciasis is limited. We describe the histopathologic features of canine ocular onchocerciasis in two dogs from California that presented clinically with firm episcleral nodules and uveitis unilaterally. Pertinent literature and pathogenesis are reviewed; recognizable clinical features and treatment are discussed. The cases presented were diagnosed via histopathology of the enucleated globes and episcleral granulomas at the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW). Positive identification of adultOnchocercawithin episcleral granulomas was made based on light-microscopy features. Histopathologic examination of both globes revealed episcleral parasites surrounded by granulomas containing few to moderate numbers of eosinophils. Other sequelae, in both cases, included lymphoplasmacytic uveitis, preiridal fibrovascular membranes, peripheral anterior synechiae, retinal degeneration, and optic nerve head cupping. Both male and female worms were present, as werein uteromicrofilariae in both cases. Worms in both cases were tentatively identified asOnchocerca lienalis. Ocular onchocerciasis should be a differential consideration in cases of canine conjunctival nodules or periorbital swelling, particularly in dogs from the western United States. [ABSTRACT FROM AUTHOR]