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Latrofa MS, Louzada-Flores VN, Maia C, Kelly MA, Verocai GG, Cantacessi C, Otranto D. Development of an indirect ELISA for the serodiagnosis of canine infection by Onchocerca lupi. Sci Rep 2024; 14:3348. [PMID: 38336818 PMCID: PMC10858053 DOI: 10.1038/s41598-024-53759-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 02/05/2024] [Indexed: 02/12/2024] Open
Abstract
Onchocerca lupi is a zoonotic filarioid parasite of dogs and cats with widespread distribution. A specific non-invasive diagnostic assay for the detection of O. lupi infections remains unavailable. This study aimed to assess the accuracy, specificity, and sensitivity of an ELISA test designed using nine peptides from two O. lupi proteins. Sera (n = 54) collected from O. lupi infected dogs from endemic areas (Portugal and USA), alongside sera from dogs positive for Dirofilaria immitis, D. repens, Cercopithifilaria bainae, and Acanthocheilonema reconditum (n = 53) from a non-endemic area for O. lupi, as well as from helminth-free dogs (n = 60), were tested. The checkerboard titration method was applied for the optimization of peptide concentrations and conjugate anti-dog dilutions. Sensitivity, specificity, and optimal cut-off values were calculated using ROC curve analysis. All peptides reacted against sera of O. lupi, with no correlation between optic density (OD) values and microfilariae (mfs) loads. Sensitivity and specificity values ranging from 85.45 to 100%, and 88.89% to 100%, respectively, were recorded for all peptides examined, with 100% specificity and sensitivity observed for peptides 40_3, 40_5, 130_3, 120_3 and 40_1, 130_5, respectively. The maximum cut-off value was observed for peptides 40_5 (0.765) and 40_3 (0.708). Testing of sera from dogs positive for other filarioids resulted in lower OD values (up to 1.565) for peptides 40_3 and 40_5 when compared with O. lupi (up to 2.929). The availability of this assay will be of value in epidemiological studies of canine O. lupi infection in both endemic and non-endemic areas, and in assessing the risk for zoonotic transmission.
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Affiliation(s)
| | | | - Carla Maia
- Global Health and Tropical Medicine, Associate Laboratory in Translation and Innovation Towards Global Health, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua de Junqueira 100, Lisboa, Portugal
| | - Maureen A Kelly
- Department of Veterinary Pathobiology, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843, USA
| | - Guilherme G Verocai
- Department of Veterinary Pathobiology, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843, USA
| | - Cinzia Cantacessi
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Domenico Otranto
- Department of Veterinary Medicine, University of Bari, Valenzano, 70010, Bari, Italy.
- Department of Veterinary Clinical Sciences, City University of Hong Kong, Kowloon Tong, Kowloon, Hong Kong.
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Gruntmeir J, Kelly M, Ramos RAN, Verocai GG. Cutaneous filarioid nematodes of dogs in the United States: Are they emerging, neglected, or underdiagnosed parasites? Front Vet Sci 2023; 10:1128611. [PMID: 36908516 PMCID: PMC9995907 DOI: 10.3389/fvets.2023.1128611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 01/30/2023] [Indexed: 02/25/2023] Open
Abstract
Filarioid nematodes, which are vector-borne parasites of cosmopolitan distribution, of dogs are medically important. They are represented by species in which microfilariae were found to be circulating in the bloodstream (e.g., Dirofilaria sp., Acanthocheilonema sp., and Brugia sp.) or skin-dwelling (e.g., Cercopithifilaria sp. and Onchocerca sp.). Those species whose microfilariae are detected in blood have been extensively studied, especially Dirofilaria immitis, due to their clinical importance. In recent decades, there has been an increased interest by the scientific community in filarioid nematodes whose microfilariae are detected in the skin because of the zoonotic aspect of Onchocerca lupi. In the United States (US), although D. immitis has been considered the main filarioid infecting dogs, the intense animal movement and global canine filarioid diversity may indicate that the likely presence of cutaneous filarioid nematodes is more common than previously expected. Hence, a question remains: Are these canine filarioid nematodes emerging, neglected, or simply underdiagnosed in the US? In this review, we provide an overview of pertinent information that briefly summarizes the biology of the different canine filarioid nematode species, clinical signs associated with infections, and currently available diagnostic tools using molecular and microscopy-based methods and highlight knowledge gaps where research and surveillance efforts remain necessary. The data herein presented serve as an alert to the scientific community about the importance of filarioid nematodes infecting dogs other than D. immitis. Additionally, the zoonotic potential of several filarioid species reinforces the necessity of a proper diagnosis and the need for broader surveillance to understand their diversity and distribution, to highlight the potential introduction of certain species, and mitigate their establishment in the country and new animal and human cases.
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Affiliation(s)
- Jeff Gruntmeir
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States.,Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, United States.,Southeastern Center of Excellence in Vector Borne Diseases, Gainesville, FL, United States
| | - Maureen Kelly
- Department of Veterinary Pathobiology, School of Veterinary Medicine and Biological Sciences, Texas A&M University, College Station, TX, United States
| | | | - Guilherme Gomes Verocai
- Department of Veterinary Pathobiology, School of Veterinary Medicine and Biological Sciences, Texas A&M University, College Station, TX, United States
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Verocai GG, Sobotyk C, Lamison A, Borst MM, Edwards EE. Autochthonous, zoonotic Onchocerca lupi in a South Texas dog, United States. Parasit Vectors 2021; 14:203. [PMID: 33858497 PMCID: PMC8048269 DOI: 10.1186/s13071-021-04707-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 03/31/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Onchocerca lupi is an emerging, zoonotic filarioid nematode associated with ocular disease in companion animals in North America and the Old World. The areas where this parasite is assumed to be endemic in the USA comprise southwestern states. Thus far, all cases reported outside of the southwest are associated with travel or animal movement. METHODS An 11-year-old, castrated male Pitbull dog from McAllen, Hidalgo County, southern Texas, with no travel history, was diagnosed with a perforating corneal ulceration of the right eye. Enucleation was performed and tissues submitted for histopathology. RESULTS Histologically, sections of two filarioid nematodes were observed. DNA was extracted from formalin-fixed paraffin-embedded tissue using a commercial kit. We performed PCR targeting the cox1 gene of the mitochondrial DNA, followed by sequencing and phylogenetic analysis. Altogether, these results confirmed the identification of the nematode specimens as O. lupi, phylogenetically belonging to haplotype 1. CONCLUSION We report the first autochthonous case of O. lupi in a dog from Hidalgo County, southern Texas, USA. Our finding suggests Texas as an additional state where this zoonotic nematode is endemic. Further investigations are required to understand the epidemiology of this parasite along the USA/Mexico border.
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Affiliation(s)
- Guilherme G Verocai
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biological Sciences, Texas A&M University, College Station, TX, 77843, USA.
| | - Caroline Sobotyk
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biological Sciences, Texas A&M University, College Station, TX, 77843, USA
| | | | - Mindy M Borst
- Texas A&M Veterinary Medical Diagnostic Laboratory, College Station, TX, USA
| | - Erin E Edwards
- Texas A&M Veterinary Medical Diagnostic Laboratory, College Station, TX, USA
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Taylor ME, Auten CR, Foster T, Ebbs E, Hofkin BV. Canine ocular onchocerciasis in New Mexico: Risk factors for disease. Vet Ophthalmol 2021; 24:288-294. [PMID: 33834584 DOI: 10.1111/vop.12889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 02/23/2021] [Accepted: 03/28/2021] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine whether dogs are at variable risk of developing canine ocular onchocerciasis based on coat color or size, factors that may influence feeding behavior of the putative vectors of Onchocerca lupi¸ the filarial nematode parasite causing this disease. ANIMALS STUDIED One hundred twenty-five client-owned dogs diagnosed with confirmed or suspected onchocerciasis. 1255 dogs without signs of this disease were utilized for comparison. PROCEDURES Dogs lacking signs of canine onchocerciasis were assessed for coat color and weight. Proportions of dogs with these characteristics were used to predict signalment in a group of dogs with this disease, if the investigated characteristics were unrelated to disease risk. Predicted values were compared statistically with observed values in the diseased dog population. Black fly color preference was assessed utilizing black, brown, and white traps and statistically assessing any differences in trapping based on trap color. RESULTS Results suggest that large, black dogs are more likely to develop canine ocular onchocerciasis than was predicted by chance alone (p = 0.012). Results for smaller dogs with other coat colors were not significant. An increased risk for black dogs was supported by trapping data, as black flies were trapped significantly more often in black traps (p < 0.001). CONCLUSION While factors other than size and color probably also influence the likelihood of O. lupi infection and disease development, our results may assist clinicians in their diagnosis of canine ocular onchocerciasis and provide them with a tool to help educate their clients as to their dogs' risk of developing this disease.
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Affiliation(s)
- Melise E Taylor
- Environmental Health Department, City of Albuquerque, Albuquerque, NM, USA
| | | | - Tania Foster
- VCA Veterinary Care Animal Hospital and Referral Center, Albuquerque, NM, USA
| | - Erika Ebbs
- The Department of Biology, Purchase College, The State University of New York, Purchase, NY, USA
| | - Bruce V Hofkin
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
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Sobotyk C, Foster T, Callahan RT, McLean NJ, Verocai GG. Zoonotic Thelazia californiensis in dogs from New Mexico, USA, and a review of North American cases in animals and humans. VETERINARY PARASITOLOGY- REGIONAL STUDIES AND REPORTS 2021; 24:100553. [PMID: 34024370 DOI: 10.1016/j.vprsr.2021.100553] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/08/2021] [Accepted: 02/27/2021] [Indexed: 12/27/2022]
Abstract
Thelazia californiensis is a spirurid nematode found in the conjunctival sac of domestic and wild animals, including humans, across the western United States of America. Herein, we report two cases of thelaziosis by T. californiensis in dogs from New Mexico, United States, based on integrated morphological and molecular approaches. Nematode specimens collected from the conjunctiva of both dogs were identified as T. californiensis based on morphology. Our study substantially expands the knowledge on morphometry of this nematode species. Therefore, these data will be useful for accurate diagnosis of thelaziosis in domestic animals, wildlife and humans in North America, using classical, microscopy-based methods. We characterized for the first time the mitochondrial cytochrome c-oxidase subunit 1 (COI) and 12S genes of T. californiensis. While these markers support the validity of T. californiensis, they were not very informative for elucidating the phylogenetic relationships among Thelazia species. Nevertheless, the characterization of these diagnostic markers for T. californiensis will be useful for studies on the epidemiology, molecular xenomonitoring of fanniid vectors, and population genetics of this multi-host, zoonotic parasite.
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Affiliation(s)
- Caroline Sobotyk
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA.
| | - Tania Foster
- Ophthalmology, VCA Veterinary Care Animal Hospital and Referral Center, Albuquerque, NM 87111, USA
| | - R Trey Callahan
- Department Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA.
| | - Nancy J McLean
- Ophthalmology, VCA Veterinary Care Animal Hospital and Referral Center, Albuquerque, NM 87111, USA
| | - Guilherme G Verocai
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA.
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Gruntmeir JM, Thompson NM, Long MT, Blagburn BL, Walden HDS. Detection of heartworm antigen without cross-reactivity to helminths and protozoa following heat treatment of canine serum. Parasit Vectors 2021; 14:71. [PMID: 33482897 PMCID: PMC7821529 DOI: 10.1186/s13071-020-04573-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 12/29/2020] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Detection of Dirofilaria immitis, or heartworm, through antigen in sera is the primary means of diagnosing infections in dogs. In recent years, the practice of heat-treating serum prior to antigen testing has demonstrated improved detection of heartworm infection. While the practice of heat-treating serum has resulted in earlier detection and improved sensitivity for heartworm infections, it has been suggested that heat treatment may cause cross reactivity with A. reconditum and intestinal helminth infections of dogs. No studies have assessed the potential cross-reactivity of these parasites with heartworm tests before and after heat treatment using blood products and an appropriate gold standard reference. METHODS Canine sera (n=163) was used to evaluate a heartworm antigen-ELISA (DiroCHEK®) and potential cross-reactivity with common parasitic infections. The heartworm status and additional parasite infections were confirmed by necropsy and adult helminth species verified morphologically or by PCR, and feces evaluated by centrifugal fecal flotation. RESULTS Intestinal parasites were confirmed in 140 of the dogs by necropsy, and 130 by fecal flotation. Acanthocheilonema reconditum microfilariae were confirmed in 22 dogs. Prevalence of heartworm infection confirmed by necropsy was 35.6% (58/163). In the 105 dogs without heartworms, specificity remained unchanged at 100% both before and after heat treatment despite confirmed infections with A. reconditum, Ancylostoma caninum, Ancylostoma brasiliense, Trichuris vulpis, Toxocara canis, Dipylidium caninum, Spirometra mansonoides, Macracanthorynchus ingens, Cystoisospora sp., Giardia sp., and Sarcocystis sp. CONCLUSIONS These findings suggest that the use of heat treatment improves sensitivity of heartworm tests and is unlikely to cause false positive antigen results due to Acanthocheilonema reconditum, intestinal helminths, and protozoal parasites in dogs.
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Affiliation(s)
- Jeff M Gruntmeir
- Department of Comparative, Diagnostic and Population Medicine, University of Florida College of Veterinary Medicine, 1945 SW 16th Avenue, Gainesville, FL, 32610, USA
| | - Nina M Thompson
- Department of Comparative, Diagnostic and Population Medicine, University of Florida College of Veterinary Medicine, 1945 SW 16th Avenue, Gainesville, FL, 32610, USA
| | - Maureen T Long
- Department of Comparative, Diagnostic and Population Medicine, University of Florida College of Veterinary Medicine, 1945 SW 16th Avenue, Gainesville, FL, 32610, USA
| | - Byron L Blagburn
- Department of Pathobiology, Auburn University College of Veterinary Medicine, 1130 Wire Road, Auburn, AL, 36849, USA
| | - Heather D S Walden
- Department of Comparative, Diagnostic and Population Medicine, University of Florida College of Veterinary Medicine, 1945 SW 16th Avenue, Gainesville, FL, 32610, USA.
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Sobotyk C, Savadelis MD, Verocai GG. Detection and cross-reaction of Dirofilaria repens using a commercial heartworm antigen test kit. Vet Parasitol 2020; 289:109302. [PMID: 33352522 DOI: 10.1016/j.vetpar.2020.109302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/18/2020] [Accepted: 10/30/2020] [Indexed: 02/07/2023]
Abstract
Antigen enzyme-linked immunosorbent assay tests are widely used for the diagnosis of heartworm infection in dogs. While commercially-available heartworm antigen tests have high sensitivity and specificity, false-negative test results can occur in dogs with low worm burdens, female-only infections, or prior to patency. The use of immune complex dissociation (ICD) methods have demonstrated increased sensitivity in the detection of Dirofilaria immitis antigens and the reversal of false-negative antigen results. However, there are concerns pertaining to false-positive antigen results due to infections of other nematode parasites, especially post-ICD. Therefore, this study evaluated the effect of heat-treatment on serum samples of dogs experimentally-infected with Dirofilaria repens during the course of infection, to assess for potential cross-reactivity on heartworm antigen tests. Archived serum samples from three dogs experimentally-infected with D. repens were utilized. All samples were tested for cross-reactivity pre- and post-heat-treatment using the DiroCHEK® Heartworm Antigen test kit throughout infection (day -9 through 404 days post-infection; dpi). All heat-treated samples tested false-positive starting at 164 dpi and continuing through 404 dpi, thereby testing positive prior to patency. No cross-reactivity was observed for any dog at any time point prior to heat-treatment. Our results suggest that the ICD method decreased the specificity of heartworm antigen tests and caused cross-reactivity of serum from dogs experimentally infected with D. repens. In conclusion, heat-treatment of serum in areas co-endemic for D. repens and D. immitis has limited clinical value, and should be used with caution.
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Affiliation(s)
- Caroline Sobotyk
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843, USA
| | - Molly D Savadelis
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Guilherme G Verocai
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843, USA; Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA.
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