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Case report: First evidence of human zoonotic infection by Onchocerca lupi (Spirurida, Onchocercidae).

ABSTRACT: In the past decades, cases of canine ocular onchocercosis have been reported worldwide, particularly in the United States and Europe. Onchocerca lupi, originally described from a wolf, has been implicated in some of these cases, and its zoonotic role has been hypothesized on the basis of the reexamination of two cases of human ocular onchocerciasis. In the present study, we describe, for the first time, the occurrence of O. lupi in the subconjunctival region of the human eye in a patient from Turkey. The nematode was identified as O. lupi based on its morphology and molecular phylogenetic analysis of partial cox1 and 12S ribosomal DNA genes. The results suggest that O. lupi should be considered in the differential diagnosis of other eye parasitic infections in humans. The role of dogs as natural hosts of O. lupi and the vectors of this zoonotic parasite need to be investigated.

SUBMITTER: Otranto D

PROVIDER: S-EPMC3005520 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Case report: First evidence of human zoonotic infection by Onchocerca lupi (Spirurida, Onchocercidae).

Otranto Domenico D Sakru Nermin N Testini Gabriella G Gürlü Vuslat P VP Yakar Konuralp K Lia Riccardo P RP Dantas-Torres Filipe F Bain Odile O

The American journal of tropical medicine and hygiene 20110101 1

In the past decades, cases of canine ocular onchocercosis have been reported worldwide, particularly in the United States and Europe. Onchocerca lupi, originally described from a wolf, has been implicated in some of these cases, and its zoonotic role has been hypothesized on the basis of the reexamination of two cases of human ocular onchocerciasis. In the present study, we describe, for the first time, the occurrence of O. lupi in the subconjunctival region of the human eye in a patient from Tu ...[more]

PMID: 21212202

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Project description:The genus Onchocerca encompasses parasitic nematodes including Onchocerca volvulus, causative agent of river blindness in humans, and the zoonotic Onchocerca lupi infecting dogs and cats. In dogs, O. lupi adult worms cause ocular lesions of various degrees while humans may bear the brunt of zoonotic onchocercosis with patients requiring neurosurgical intervention because of central nervous system localization of nematodes. Though the zoonotic potential of O. lupi has been well recognized from human cases in Europe, the United States and the Middle East, a proper therapy for curing this parasitic infection in dogs is lacking. To evaluate the efficacy of oxfendazole, 11 out of the 21 client-owned dogs (21/123; 17.1%) positive for skin-dwelling O. lupi microfilariae (mfs), were enrolled in the efficacy study and were treated with oxfendazole (50 mg/kg) per OS once a day for 5 (G2) or 10 (G3) consecutive days or were left untreated (G1). The efficacy of oxfendazole in the reduction of O. lupi mfs was evaluated by microfilarial count and by assessing the percentage of mfs reduction and mean microfilaricidal efficacy, whereas the efficacy in the reduction of ocular lesions was evaluated by ultrasound imaging. All dogs where subjected to follow-ups at 30 (D30), 90 (D90) and 180 (D180) days post-treatment. The percentage of reduction of mfs was 78% for G2 and 12.5% for G3 at D180. The mean microfilaricidal efficacy of oxfendazole in the treatment of canine onchocercosis by O. lupi at D30, D90 and D180 was 41%, 81% and 90%, in G2 and 40%, 65% and 70%, in G3, respectively. Retrobulbar lesions did not reduce from D0 to D180 in control group (dogs in G1), whereas all treated dogs (in G2 and G3) had slightly decreased ocular lesions. Percentage of reduction of ocular lesions by ultrasound examination was 50% and 47.5% in G2 and G3 at D180, respectively. Despite the decrease in ocular lesions in all treated dogs (G2 and G3), oxfendazole was ineffective in reducing ocular lesions and skin-dwelling O. lupi mfs in treated dogs (G2 and G3) in a six-month follow-up period. Here we discuss the need for more reliable diagnostic techniques and efficient treatment protocols to better plan future intervention strategies.

Project description:Zoonotic infections with Onchocerca species are uncommon, and to date only 25 clinical cases have been reported worldwide. In Japan, five previous zoonotic infections were concentrated in Oita, Kyushu (the southern island), with one previous case in Hiroshima in the western part of Honshu (the main island). The causative agent in Japan was identified as Onchocerca dewittei japonica Uni, Bain & Takaoka, 2001 from Japanese wild boars (Sus scrofa leucomystax Temminck, 1842). Here we report two infections caused by a female and male O. dewittei japonica, respectively, among residents of Hiroshima and Shimane Prefectures in the western part of Honshu.In both cases, nodules were surgically removed. The parasites in nodules were identified on the basis of their histopathological characteristics. Identification was confirmed by sequencing the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene from worms in the tissues used in the histological preparations.Case 1 was a 61-year-old woman from Hiroshima Prefecture who complained of a painful subcutaneous nodule on the back of her right hand. The causative agent was identified as a female O. dewittei japonica owing to transverse ridges on the cuticle and molecular analysis. Case 2 was a 78-year-old woman from Shimane Prefecture who had a painful nodule in the left temporal region. Histopathological characteristics and cox1 sequencing of the worm indicated that the causative agent was a male O. dewittei japonica.For Cases 1 and 2, we diagnosed the causative agents as a female and male O. dewittei japonica, respectively. These findings indicate the spread of a zoonosis caused by O. dewittei japonica in the western part of Honshu, where wild boars have recently extended their habitats because of decreased annual snowfall, unused rice fields and a decline in the number of hunters in Japan. The O. dewittei japonica infection rate among wild boars was reported as 78% in Shimane Prefecture, in the western part of Honshu. Therefore, in the near future, zoonotic onchocercosis is likely to occur in Honshu as well as Kyushu, where wild boars, blackfly vectors and humans share the same habitat.

Project description:BackgroundOf increasing importance to the medical and veterinary communities is the zoonotic filarioid nematode Onchocerca lupi. Onchocercosis, thus far found in wolves, dogs, cats and humans, is diagnosed via skin snips to detect microfilariae and surgical removal of adults from the eye of the host. These methods are time-consuming, laborious and invasive, highlighting the need for new tools for the diagnosis of O. lupi in susceptible hosts. Symptoms related to the presence of the adults in the eye can range from none apparent to severe, including blindness. No reliable chemotherapeutic protocols are available, as yet, to eliminate the infection. Paramyosin, an invertebrate-specific protein, has been well-studied as an allergen, diagnostic marker and vaccine candidate. The aim of this study, therefore, was to isolate and characterise paramyosin from O. lupi to assess its suitability for the development of a serological diagnostic assay.MethodsThe adult and microfilarial stages of O. lupi were isolated from the eyes and skin of a 3-year-old male dog. Total RNA was extracted and reverse transcribed into single stranded cDNA. Reverse-transcription PCR was used to isolate a full-length paramyosin cDNA from adult worms and to investigate the temporal expression patterns of this gene. All amplicons were sequenced using dideoxy chain termination sequencing. Bioinformatics was used to predict the amino acid sequence of the gene, to compare the DNA and protein sequences with those available in public databases and to investigate the phylogenetic relationship of all molecules. Antibody binding sites were predicted using bioinformatics and mapped along with published antigenic epitopes against the O. lupi paramyosin protein. The native protein, and three smaller recombinantly expressed peptides, were subjected to western blot using serum from dogs both positive and negative for O. lupi.ResultsParamyosin of O. lupi was herein molecularly characterized, encoded by a transcript of 2,643 bp and producing a protein of 881 amino acids (101.24 kDa). The paramyosin transcript was detected, by reverse transcription PCR, in adults and microfilariae, but not in eggs. Phylogenetic analysis indicates that this molecule clusters with paramyosins from other filarioids to the exclusion of those from other taxa. A total of 621 unique antibody binding epitopes were predicted for this protein and another 28 were conserved in other organisms. This information was used to design three peptides, for recombinant expression, to identify the antibody binding epitope(s) and reduce potential cross-reactivity with serum from dogs infected with other filarioid nematodes. Native paramyosin, purified from microfilariae and adults, was detected by antibodies present in serum from dogs with known O. lupi infections.ConclusionsData provided herein may assist in the development of a serological diagnostic test, based on antibodies to O. lupi paramyosin, for the diagnosis of this infection, in order to gain more information on the real distribution of this little known filarioid of zoonotic concern.

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Case report: First evidence of human zoonotic infection by Onchocerca lupi (Spirurida, Onchocercidae).

Publications

Case report: First evidence of human zoonotic infection by Onchocerca lupi (Spirurida, Onchocercidae).

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