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Power RI, Šlapeta J. Delayed canine heartworm (Dirofilaria immitis) microfilarial reduction following Advocate™ for dogs (imidacloprid, moxidectin) treatment. Vet J 2024; 307:106209. [PMID: 39098470 DOI: 10.1016/j.tvjl.2024.106209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Revised: 05/28/2024] [Accepted: 07/29/2024] [Indexed: 08/06/2024]
Abstract
Macrocyclic lactone (ML) anthelmintics are currently the only class of drugs available for canine heartworm prevention. Recent reports of Dirofilaria immitis infection occurring in dogs reportedly receiving 'rigorous' prevention in Queensland, Australia, coupled with the confirmation of ML-resistant isolates in the USA, has led to speculation about the potential emergence of ML-resistance in Australia. In this study, we describe two cases (Dog 1 and 2) of asymptomatic canine heartworm disease in Townsville, Australia, that were reportedly receiving 'rigorous' heartworm prevention according to the owners' claims. We aimed to deploy currently available tools to assess the phenotypic and genotypic ML-resistance status of these two dogs. For phenotypic testing, we performed an in-vivo 7-day microfilariae suppression test using a dose of spot-on moxidectin (Advocate™ for Dogs, 100 g/L imidacloprid + 25 g/L moxidectin). This formulation is marketed as Advantage Multi® for Dogs in the USA, which claims a D. immitis microfilaricidal effect. For genetic testing, an Illumina amplicon metabarcoding approach was used to target single nucleotide polymorphisms (SNPs) previously associated with ML-resistance in D. immitis from the USA. Dog 1 and Dog 2 demonstrated <10 % and <40 % reductions in circulating microfilariae seven days after moxidectin treatment, respectively. These phenotypes were not corroborated by genetic SNP testing, as both dogs were classified as susceptible across all examined markers. To streamline testing of D. immitis SNPs, we developed a rhAmp™ SNP qPCR approach for rapidly genotyping suspect cases of ML-resistant infections at the two major loci (L15709_A and L30575). These findings illustrate a phenomenon shown in some heartworm cases outside the USA, whereby infected dogs are failing to see marked reductions in microfilaraemia after ML treatment but possess an ML-susceptible genotype.
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Affiliation(s)
- Rosemonde Isabella Power
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, New South Wales 2006, Australia
| | - Jan Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, New South Wales 2006, Australia; Sydney Infectious Diseases Institute, The University of Sydney, New South Wales 2006, Australia.
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2
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Traversa D, Diakou A, Colombo M, Kumar S, Long T, Chaintoutis SC, Venco L, Betti Miller G, Prichard R. First case of macrocyclic lactone-resistant Dirofilaria immitis in Europe - Cause for concern. Int J Parasitol Drugs Drug Resist 2024; 25:100549. [PMID: 38795510 PMCID: PMC11153229 DOI: 10.1016/j.ijpddr.2024.100549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 05/20/2024] [Accepted: 05/20/2024] [Indexed: 05/28/2024]
Abstract
Heartworm disease caused by the nematode Dirofilaria immitis is one of the most important parasitoses of dogs. The treatment of the infection is long, complicated, risky and expensive. Conversely, prevention is easy, safe, and effective and it is achieved by the administration of macrocyclic lactones (MLs). In recent years, D. immitis strains resistant to MLs have been described in Southern USA, raising concerns for possible emergence, or spreading in other areas of the world. The present study describes the first case of ML-resistant D. immitis in a dog in Europe. The dog arrived in Rome, Italy, from USA in 2023. Less than 6 months after its arrival in Italy, the dog tested positive for D. immitis circulating antigen and microfilariae, despite it having received monthly the ML milbemycin oxime (plus an isoxazoline) after arrival. The microfilariae suppression test suggested a resistant strain. Microfilariae DNA was examined by droplet digital PCR-based duplex assays targeting four marker positions at single nucleotide polymorphisms (SNP1, SNP2, SNP3, SNP7) which differentiate resistant from susceptible isolates. The genetic analysis showed that microfilariae had a ML-resistant genotype at SNP1 and SNP7 positions, compatible with a resistant strain. It is unlikely that the dog acquired the infection after its arrival in Europe, while it is biologically and epidemiologically plausible that the dog was already infected when imported from USA to Europe. The present report highlights the realistic risk of ML-resistant D. immitis strains being imported and possibly transmitted in Europe and other areas of the world. Monitoring dogs travelling from one area to another, especially if they originate from regions where ML-resistance is well-documented, is imperative. Scientists, practitioners, and pet owners should be aware of the risk and remain vigilant against ML-resistance, in order to monitor and reduce the spreading of resistant D. immitis.
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Affiliation(s)
- Donato Traversa
- Department of Veterinary Medicine, University of Teramo, 64100, Teramo, Italy.
| | - Anastasia Diakou
- Laboratory of Parasitology and Parasitic Diseases, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece.
| | - Mariasole Colombo
- Department of Veterinary Medicine, University of Teramo, 64100, Teramo, Italy.
| | - Sohini Kumar
- Institute of Parasitology, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte Anne-de-Bellevue, QC, H9X3V9, Canada.
| | - Thavy Long
- Institute of Parasitology, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte Anne-de-Bellevue, QC, H9X3V9, Canada.
| | - Serafeim C Chaintoutis
- Diagnostic Laboratory, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54627, Thessaloniki, Greece.
| | - Luigi Venco
- Ospedale Veterinario Città di Pavia, 27100, Pavia, Italy.
| | | | - Roger Prichard
- Institute of Parasitology, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte Anne-de-Bellevue, QC, H9X3V9, Canada.
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Mia MM, Allaie IM, Zhang X, Li K, Khan SM, Kadotani S, Witola WH. Characterization of a unique catechol-O-methyltransferase as a molecular drug target in parasitic filarial nematodes. PLoS Negl Trop Dis 2024; 18:e0012473. [PMID: 39213433 PMCID: PMC11392244 DOI: 10.1371/journal.pntd.0012473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 09/12/2024] [Accepted: 08/19/2024] [Indexed: 09/04/2024] Open
Abstract
BACKGROUND Filarial nematodes cause severe illnesses in humans and canines including limb deformities and disfigurement, heart failure, blindness, and death, among others. There are no vaccines, and current drugs against filarial nematodes infections have only modest effects and are prone to complications. METHODOLOGY/PRINCIPAL FINDINGS We identified a gene (herein called DiMT) encoding an S-adenosyl-L-methionine (SAM)-dependent methyltransferase with orthologs in parasite filarial worms but not in mammals. By in silico analysis, DiMT possesses catalytic sites for binding SAM and catecholamines with high affinity. We expressed and purified recombinant DiMT protein and used it as an enzyme in a series of SAM-dependent methylation assays. DiMT acted specifically as a catechol-O-methyltransferase (COMT), catalyzing catabolic methylation of dopamine, and depicted Michaelis Menten kinetics on substrate and co-substrate. Among a set of SAM-dependent methyltransferase inhibitors, we identified compounds that bound with high affinity to DiMT's catalytic sites and inhibited its enzymatic activity. By testing the efficacy of DiMT inhibitors against microfilariae of Dirofilaria immitis in culture, we identified three inhibitors with concentration- and time-dependent effect of killing D. immitis microfilariae. Importantly, RNAi silencing of a DiMT ortholog in Caenorhabditis elegans has been shown to be lethal, likely as a result of excessive accumulation of active catecholamines that inhibit worm locomotion, pharyngeal pumping and fecundity. CONCLUSIONS/SIGNIFICANCE Together, we have unveiled DiMT as an essential COMT that is conserved in parasitic filarial nematodes, but is significantly different from mammalian COMTs and, therefore, is a viable target for development of novel drugs against filarial nematode infections.
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Affiliation(s)
- Md Mukthar Mia
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Idrees Mehraj Allaie
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Xuejin Zhang
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Kun Li
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
- Institute of Traditional Chinese Veterinary Medicine, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Shahbaz M Khan
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Saki Kadotani
- Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - William H Witola
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
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4
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Power RI, Doyle SR, Šlapeta J. Whole genome amplification and sequencing of individual Dirofilaria immitis microfilariae. Exp Parasitol 2024; 263-264:108806. [PMID: 39009178 DOI: 10.1016/j.exppara.2024.108806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 05/17/2024] [Accepted: 07/12/2024] [Indexed: 07/17/2024]
Abstract
Dirofilaria immitis is a filarial parasitic nematode of veterinary significance. With the emergence of drug-resistant isolates in the USA, it is imperative to determine the likelihood of resistance occurring in other regions of the world. One approach is to conduct population genetic studies across an extensive geographical range, and to sequence the genomes of individual worms to understand genome-wide genetic variation associated with resistance. The immature life stages of D. immitis found in the host blood are more accessible and less invasive to sample compared to extracting adult stages from the host heart. To assess the use of immature life stages for population genetic analyses, we have performed whole genome amplification and whole-genome sequencing on nine (n = 9) individual D. immitis microfilaria samples isolated from dog blood. On average, less than 1% of mapped reads aligned to each D. immitis genome (nuclear, mitochondrial, and Wolbachia endosymbiont). For the dog genome, an average of over 99% of mapped reads aligned to the nuclear genome and less than 1% aligned to the mitochondrial genome. The average coverage for all D. immitis genomes and the dog nuclear genome was less than 1, while the dog mitochondrial genome had an average coverage of 2.87. The overwhelming proportion of sequencing reads mapping to the dog host genome can be attributed to residual dog blood cells in the microfilariae samples. These results demonstrate the challenges of conducting genome-wide studies on individual immature parasite life stages, particularly in the presence of extraneous host DNA.
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Affiliation(s)
- Rosemonde I Power
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, New South Wales, 2006, Australia
| | - Stephen R Doyle
- Wellcome Sanger Institute, Cambridgeshire, CB10 1SA, United Kingdom
| | - Jan Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, New South Wales, 2006, Australia; Sydney Infectious Diseases Institute, The University of Sydney, New South Wales, 2006, Australia.
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5
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Fisher PT, Keller K, Prichard RK. Investigating Dirofilaria immitis isolates infecting domestic canines and their susceptibility/resistance patterns to macrocyclic lactones in the northern region of the Mississippi Delta area (southeast Missouri). Vet Parasitol 2024; 329:110199. [PMID: 38781830 DOI: 10.1016/j.vetpar.2024.110199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 05/25/2024]
Abstract
Previous reports of macrocyclic lactone (ML) resistance in Dirofilaria immitis, the parasitic nematode which causes heartworm disease, have mainly been from the southern Mississippi Delta region. Southeast Missouri (SEMO), forming the northern boundary of this region, has not previously been well studied. The area is an ideal propagation region for heartworm infection and possibly for the spread of ML resistance. To assess whether D. immitis isolates infecting domestic canines in SEMO exhibit evidence of resistance to MLs, domestic canines, presented to veterinary facilities testing positive for heartworms through antigen and microfilariae (MF) examination, were utilized in the study. Using a descriptive epidemiological cross-sectional study, from March 2021 through February 2022, blood sample collection from 96 canines living in SEMO testing positive for heartworms were analyzed. MiSeq technology was utilized to sequence specific genetic markers associated with susceptibility/resistance for MLs in D. immitis isolates. Genomic data revealed most D. immitis isolates had genotypic profiles consistent with resistance to MLs. Of the 96 samples tested, 91 (94.8%) had a resistant genotype, 4 (4.2%) had a mixed genotype, and 1 sample (1%) genotyped as susceptible. While detailed and reliable medical histories were not available for most canines, detailed medical history from 2 canines indicated evidence of phenotypic resistance that was consistent with their genotypes. However, in vivo preventive tests are needed to confirm a high frequency of phenotypic ML resistance in D. immitis from this region. Increasing resistance patterns to MLs indicate the approach to heartworm prevention/treatment protocol should be reconsidered. New measures may be required to stop heartworm disease.
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Affiliation(s)
- Peggy T Fisher
- University of Missouri-College of Veterinary Medicine, 1520 East Rollins, Columbia, MO 65211, USA.
| | - Kathy Keller
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte Anne de Bellevue, QC H9X3V9, Canada
| | - Roger K Prichard
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte Anne de Bellevue, QC H9X3V9, Canada
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Mwacalimba K, Sheehy J, Adolph C, Savadelis M, Kryda K, Poulsen Nautrup B. A review of moxidectin vs. other macrocyclic lactones for prevention of heartworm disease in dogs with an appraisal of two commercial formulations. Front Vet Sci 2024; 11:1377718. [PMID: 38978634 PMCID: PMC11229481 DOI: 10.3389/fvets.2024.1377718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Accepted: 06/04/2024] [Indexed: 07/10/2024] Open
Abstract
Macrocyclic lactones (MLs) are the only drug class currently licensed for heartworm disease prophylaxis. Macrocyclic lactones kill third- and fourth-stage larvae of Dirofilaria immitis, thus preventing the development of adult worms in dogs, which are responsible for heartworm disease, a potentially life-threatening condition. Despite considerable overlap in terms of endectocide spectrum, several important differences distinguish moxidectin from other MLs. Moxidectin has beneficial pharmacokinetic characteristics, such as a longer half-life and greater tissue distribution compared to ivermectin. Additionally, moxidectin has a greater margin of safety compared to ivermectin in dogs with ABCB1 (previously MDR1) gene-defect, which is commonly recognized in collies and other breeds. Multiple laboratory studies have shown that moxidectin is more effective than other commonly used heartworm preventives against resistant strains of D. immitis. This improved efficacy benefits individual dogs and helps reduce the risk of spreading resistant strains within the community. Despite the presence of proven resistant strains in the United States, non-compliance with preventive measures remains a major factor contributing to the diagnosis of heartworm disease in dogs. In retrospective analyses, the oral moxidectin combination product Simparica Trio® (sarolaner, moxidectin, and pyrantel) was associated with increased compliance, resulting in more time of protection compared to dogs receiving flea/tick and heartworm preventive products separately. Compliance with the extended-release moxidectin injectables ProHeart® 6 and ProHeart® 12 was higher than with monthly heartworm preventives, as they provide 6 months or a full year of protection with one single injection, respectively, and revenues remain in the veterinary clinics as injectable moxidectin cannot be sourced through online retailers.
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Affiliation(s)
| | - Jenifer Sheehy
- Veterinary Professional Services, Zoetis, Parsippany, NJ, United States
| | | | - Molly Savadelis
- Veterinary Medicine Research and Development, Zoetis, Kalamazoo, MI, United States
| | - Kristina Kryda
- Veterinary Medicine Research and Development, Zoetis, Kalamazoo, MI, United States
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Kumar S, Che H, Chiummo R, Heuer L, Schneider C, Werr M, Guerino F, Papadopolous E, Diakou A, Mihalca AD, Traversa D, Di Cesare A, Long T, Prichard RK. Genotyping USA laboratory-maintained isolates and European clinical isolates of Dirofilaria immitis to assess macrocyclic lactone susceptibility or resistance at predictive SNP sites using droplet digital PCR. Vet Parasitol 2024; 328:110181. [PMID: 38582015 DOI: 10.1016/j.vetpar.2024.110181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/02/2024] [Accepted: 04/02/2024] [Indexed: 04/08/2024]
Abstract
Dirofilaria immitis is a parasitic nematode that causes cardiovascular dirofilariosis ("heartworm disease") primarily in canids. The principal approach for mitigating heartworm infection involves the use of macrocyclic lactone (ML) for prophylaxis. Recent research has substantiated the emergence of D. immitis displaying resistance to MLs in the USA. Numerous factors, such as the mobility of companion animals and competent vectors could impact the spread of drug resistance. Genomic analysis has unveiled that isolates resistant to ML exhibit unique genetic profiles when compared to their wild-type (susceptible) counterparts. Out of the ten single nucleotide polymorphism (SNP) markers validated in clinical samples of D. immitis from the USA, four have demonstrated their effectiveness in distinguishing between isolates with varying ML efficacy phenotypes. This study explores the potential of these confirmed SNPs for conducting surveillance studies. Genotypic analysis using SNP markers emerges as a valuable tool for carrying out surveys and evaluating individual clinical isolates. Two USA laboratory-maintained isolates (Berkeley, WildCat) and twenty-five random European clinical samples of either adult worms or microfilariae (mf) pools isolated from domestic dogs, were tested by droplet digital PCR (ddPCR)-based duplex assay. This approach elucidates genetic evidence pertaining to the development of drug resistance and provides baseline data on resistance related genotypes in Europe. The data on these clinical samples suggests genotypes consistent with the continued efficacy of ML treatment regimens in Europe. In addition, this assay can be significant in discriminating cases of drug-resistance from those possibly due to non-compliance to the recommended preventive protocols.
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Affiliation(s)
- Sohini Kumar
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X3V9, Canada.
| | - Hua Che
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X3V9, Canada
| | - Rafael Chiummo
- MSD Animal Health, Zur Propstei, Schwabenheim 55270, Germany
| | - Lea Heuer
- MSD Animal Health, Zur Propstei, Schwabenheim 55270, Germany
| | | | - Margaret Werr
- MSD Animal Health, Zur Propstei, Schwabenheim 55270, Germany
| | - Frank Guerino
- Merck Animal Health, 126 E. Lincoln Avenue, Rahway, NJ 07065-0900, USA
| | - Elias Papadopolous
- School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Anastasia Diakou
- School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Andrei Daniel Mihalca
- Department of Parasitology and Parasitic Diseases, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, Calea Mănăștur 3-5, Cluj-Napoca 400372, Romania; Parasitology Consultancy Group, Corușu, Cluj 145B, Romania
| | - Donato Traversa
- Department of Veterinary Medicine, Località Piano d'Accio snc, Teramo 64100, Italy
| | - Angela Di Cesare
- Department of Veterinary Medicine, Località Piano d'Accio snc, Teramo 64100, Italy
| | - Thavy Long
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X3V9, Canada.
| | - Roger K Prichard
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X3V9, Canada.
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Gandasegui J, Power RI, Curry E, Lau DCW, O'Neill CM, Wolstenholme A, Prichard R, Šlapeta J, Doyle SR. Genome structure and population genomics of the canine heartworm Dirofilaria immitis. Int J Parasitol 2024; 54:89-98. [PMID: 37652224 DOI: 10.1016/j.ijpara.2023.07.006] [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: 04/24/2023] [Revised: 07/24/2023] [Accepted: 07/28/2023] [Indexed: 09/02/2023]
Abstract
The heartworm, Dirofilaria immitis, is a filarial parasitic nematode responsible for significant morbidity and mortality in wild and domesticated canids. Resistance to macrocyclic lactone drug prevention represents a significant threat to parasite control and has prompted investigations to understand the genetic determinants of resistance. This study aimed to improve the genomic resources of D. immitis to enable a more precise understanding of how genetic variation is distributed within and between parasite populations worldwide, which will inform the likelihood and rate by which parasites, and in turn, resistant alleles, might spread. We have guided the scaffolding of a recently published genome assembly for D. immitis (ICBAS_JMDir_1.0) using the chromosomal-scale reference genomes of Brugia malayi and Onchocerca volvulus, resulting in an 89.5 Mb assembly composed of four autosomal- and one sex-linked chromosomal-scale scaffolds representing 99.7% of the genome. Publicly available and new whole-genome sequencing data from 32 D. immitis samples from Australia, Italy and the USA were assessed using principal component analysis, nucleotide diversity (Pi) and absolute genetic divergence (Dxy) to characterise the global genetic structure and measure within- and between-population diversity. These population genetic analyses revealed broad-scale genetic structure among globally diverse samples and differences in genetic diversity between populations; however, fine-scale subpopulation analysis was limited and biased by differences between sample types. Finally, we mapped single nucleotide polymorphisms previously associated with macrocyclic lactone resistance in the new genome assembly, revealing the physical linkage of high-priority variants on chromosome 3, and determined their frequency in the studied populations. This new chromosomal assembly for D. immitis now allows for a more precise investigation of selection on genome-wide genetic variation and will enhance our understanding of parasite transmission and the spread of genetic variants responsible for resistance to treatment.
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Affiliation(s)
- Javier Gandasegui
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic - University of Barcelona, Barcelona, Spain.
| | - Rosemonde I Power
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, NSW, Australia.
| | - Emily Curry
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, QC, Canada.
| | - Daisy Ching-Wai Lau
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, NSW, Australia.
| | - Connor M O'Neill
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.
| | - Adrian Wolstenholme
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.
| | - Roger Prichard
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, QC, Canada.
| | - Jan Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, NSW, Australia.
| | - Stephen R Doyle
- Wellcome Sanger Institute, Cambridgeshire CB10 1SA, United Kingdom.
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9
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Lau DCW, Power RI, Šlapeta J. Exploring multiplex qPCR as a diagnostic tool for detecting microfilarial DNA in dogs infected with Dirofilaria immitis: A comparative analysis with the modified Knott's test. Vet Parasitol 2024; 325:110097. [PMID: 38104431 DOI: 10.1016/j.vetpar.2023.110097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/10/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023]
Abstract
Current recommendations to diagnose cardiopulmonary dirofilariosis in dogs caused by Dirofilaria immitis involves tandem antigen and circulating microfilariae tests. The modified Knott's test is an important tool in heartworm diagnosis, allowing identification of circulating microfilariae. However, the subjective nature of the modified Knott's test affects its accuracy and diagnostic laboratories usually do not provide a quantitative outcome. Quantitative enumeration of microfilariae enables clinicians to track treatment progress and acts as a proxy for detecting emerging macrocyclic lactone resistance. There is a need for better diagnostic tools suitable for routine use to efficiently and accurately quantify the presence of D. immitis microfilaremia. The aim of this study was to determine whether the quantitative modified Knott's test can be substituted by multiplex quantitative polymerase chain reaction (qPCR) targeting D. immitis and associated Wolbachia endosymbiont DNA in canine blood samples. To do this, genomic DNA samples (n = 161) from Australian dogs, collected as part of a previous 2021 study, were assessed in a TaqMan qPCR targeting DNA of D. immitis, Wolbachia sp. and Canis lupus familiaris. Of the 161 genomic DNA samples, eight were considered positive for D. immitis microfilariae. The qPCR assay demonstrated good efficiency (E = 90 to 110%, R2 > 0.94). Considering the performance and efficient use of bench time, this TaqMan qPCR assay is a suitable alternative to the modified Knott's test for quantitative enumeration of microfilariae (Cohen's kappa coefficient [κ]: κ = 1 using D. immitis qPCR marker, κ = 0.93 using Wolbachia qPCR marker). The qPCR data demonstrated a comparable result to that of the quantitative modified Knott's test in a 2022 survey of D. immitis in Australian dogs (n = 23) before and after macrocyclic lactone (ML) administration. Improving the detection and diagnosis of canine heartworm infections will assist veterinarians in better managing and controlling disease outcomes and will be valuable for tracking the spread of ML resistance in Australia.
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Affiliation(s)
- Daisy Ching-Wai Lau
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, New South Wales 2006, Australia
| | - Rosemonde Isabella Power
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, New South Wales 2006, Australia
| | - Jan Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, New South Wales 2006, Australia; The University of Sydney Institute for Infectious Diseases, New South Wales 2006, Australia.
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Mukherjee A, Kar I, Patra AK. Understanding anthelmintic resistance in livestock using "omics" approaches. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:125439-125463. [PMID: 38015400 DOI: 10.1007/s11356-023-31045-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 11/08/2023] [Indexed: 11/29/2023]
Abstract
Widespread and improper use of various anthelmintics, genetic, and epidemiological factors has resulted in anthelmintic-resistant (AR) helminth populations in livestock. This is currently quite common globally in different livestock animals including sheep, goats, and cattle to gastrointestinal nematode (GIN) infections. Therefore, the mechanisms underlying AR in parasitic worm species have been the subject of ample research to tackle this challenge. Current and emerging technologies in the disciplines of genomics, transcriptomics, metabolomics, and proteomics in livestock species have advanced the understanding of the intricate molecular AR mechanisms in many major parasites. The technologies have improved the identification of possible biomarkers of resistant parasites, the ability to find actual causative genes, regulatory networks, and pathways of parasites governing the AR development including the dynamics of helminth infection and host-parasite infections. In this review, various "omics"-driven technologies including genome scan, candidate gene, quantitative trait loci, transcriptomic, proteomic, and metabolomic approaches have been described to understand AR of parasites of veterinary importance. Also, challenges and future prospects of these "omics" approaches are also discussed.
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Affiliation(s)
- Ayan Mukherjee
- Department of Animal Biotechnology, West Bengal University of Animal and Fishery Sciences, Nadia, Mohanpur, West Bengal, India
| | - Indrajit Kar
- Department of Avian Sciences, West Bengal University of Animal and Fishery Sciences, Nadia, Mohanpur, West Bengal, India
| | - Amlan Kumar Patra
- American Institute for Goat Research, Langston University, Oklahoma, 73050, USA.
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Kumar S, Prichard RK, Long T. Droplet digital PCR as a tool to detect resistant isolates of Dirofilaria immitis. Int J Parasitol Drugs Drug Resist 2023; 23:10-18. [PMID: 37540993 PMCID: PMC10407818 DOI: 10.1016/j.ijpddr.2023.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 07/14/2023] [Accepted: 07/16/2023] [Indexed: 08/06/2023]
Abstract
Prevention of canine heartworm disease, caused by Dirofilaria immitis, relies on macrocyclic lactones for which drug resistance is now a concern. Although genetic polymorphisms have been associated with resistance in D. immitis populations, the mechanism is still not well understood. The lack of reliable in vitro assays to detect resistance is a limitation for confirming resistance. Ten single nucleotide polymorphisms (SNPs) were previously clinically validated in D. immitis resistant isolates, using the MiSeq platform. This technique although useful for research studies is expensive and does not facilitate rapid detection of these markers in small numbers of clinical samples. We developed a droplet digital PCR protocol for detecting SNPs correlating with ML resistance. Specific primers and hydrolysis probes encompassing the wildtype and mutant alleles were designed to amplify the SNP targets from genomic DNA of different D. immitis isolates. Allele frequencies were determined and the suitability of the ddPCR assay was assessed and compared with MiSeq data. The ddPCR assay accurately detected and quantified alternate nucleotides in two isolates of reference, the ML-susceptible Missouri (MO) and ML-resistant JYD-34, at the previously identified SNP positions. The presence of the SNPs was also determined in additional isolates with known or putative susceptible or resistant phenotypes. We observed SNP1 and SNP2 are more predictive markers and appear suitable for rapid detection and monitoring of drug resistance. Our results suggested that ddPCR could be employed to distinguish infection due to actual genetic resistance from infection with susceptible parasites and also for rapid detection of isolates not only with ML susceptible and resistant genotypes but also mixed genotypes that correspond to heterogeneous isolates containing a mixed population of ML susceptible and resistant parasites. DdPCR may be a useful tool for conducting surveys, or assessments of individual isolates, for genetic evidence of resistance or developing resistance.
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Affiliation(s)
- Sohini Kumar
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, H9X3V9, QC, Canada
| | - Roger K Prichard
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, H9X3V9, QC, Canada
| | - Thavy Long
- Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, H9X3V9, QC, Canada.
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12
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Nielsen MK, Kaplan RM, Abbas G, Jabbar A. Biological implications of long-term anthelmintic treatment: what else besides resistance are we selecting for? Trends Parasitol 2023; 39:945-953. [PMID: 37633759 DOI: 10.1016/j.pt.2023.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 08/02/2023] [Accepted: 08/03/2023] [Indexed: 08/28/2023]
Abstract
Long-term intensive use of anthelmintics for parasite control of livestock, companion animals, and humans has resulted in widespread anthelmintic resistance, a problem of great socioeconomic significance. But anthelmintic therapy may also select for other biological traits, which could have implications for anthelmintic performance. Here, we highlight recent examples of changing parasite dynamics following anthelmintic administration, which do not fit the definition of anthelmintic resistance. We also consider other possible examples in which anthelmintic resistance has clearly established, but where coselection for other biological traits may have also occurred. We offer suggestions for collecting more information and gaining a better understanding of these phenomena. Finally, we propose research questions that require further investigation and make suggestions to help address these knowledge gaps.
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Affiliation(s)
- Martin K Nielsen
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
| | - Ray M Kaplan
- School of Veterinary Medicine, St George's University, Grenada, West Indies
| | - Ghazanfar Abbas
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria, Australia
| | - Abdul Jabbar
- Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria, Australia
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13
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Mitchell E, Tielemans E, McCall JW, Baker C, Martin E, Frost J, Yoon S, Fankhauser B. Efficacy of an oral combination of moxidectin, afoxolaner, and pyrantel pamoate for the prevention of heartworm disease in dogs. Res Vet Sci 2023; 162:104957. [PMID: 37454406 DOI: 10.1016/j.rvsc.2023.104957] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
Dirofilaria immitis, the mosquito-borne agent of dirofilariosis, a chronic and sometimes fatal cardiopulmonary canine disease, is endemic in most warm and temperate regions in the world. The efficacy of an oral endectoparasiticide product (test product or TP) combining moxidectin, afoxolaner, and pyrantel pamoate was evaluated for the prevention of heartworm disease in dogs, in two laboratory and one field studies. In each laboratory study, 20 D. immitis-naïve beagle dogs were experimentally infected with D. immitis. Ten control dogs were sham-treated, and ten dogs were administered the TP targeting the minimum effective dose, six times monthly and starting 30 days post infection. At necropsy seven months after inoculations, no heartworms were found in any of the TP treated dog, whereas 19 to 42 live heartworms were found in the control dogs. In each study, treatment efficacy was 100% and the difference between treated and untreated groups was highly significant (p < 0.0001). A field study was conducted through the full transmission season in several heartworm-endemic regions of the United States. One hundred and twenty client-owned dogs that were negative for D. immitis at enrollment were administered twelve monthly oral doses of the TP at label dose. Blood tests for D. immitis antigen and modified Knott's tests for microfilariae remained negative through the full duration of the study, demonstrating that all dogs were protected from heartworm infection during the full transmission season. These studies demonstrated that TP administered monthly for at least six doses is effective at preventing dirofilariosis.
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Affiliation(s)
- Elizabeth Mitchell
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA 30601, USA
| | - Eric Tielemans
- Boehringer Ingelheim Animal Health, 29 avenue Tony Garnier, 69007 Lyon, France.
| | - John W McCall
- TRS Labs, Inc., 215 Paradise Blvd., Athens, GA 30607, USA
| | - Christine Baker
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA 30601, USA
| | - Elizabeth Martin
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA 30601, USA
| | - Justin Frost
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA 30601, USA
| | - Stephen Yoon
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA 30601, USA
| | - Becky Fankhauser
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, Athens, GA 30601, USA
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14
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Geary TG. New paradigms in research on Dirofilaria immitis. Parasit Vectors 2023; 16:247. [PMID: 37480077 PMCID: PMC10362759 DOI: 10.1186/s13071-023-05762-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 03/30/2023] [Indexed: 07/23/2023] Open
Abstract
BACKGROUND Since the advent of ivermectin (along with melarsomine and doxycycline), heartworm has come to be viewed as a solved problem in veterinary medicine, diminishing investment into non-clinical research on Dirofilaria immitis. However, heartworm infections continue to pose problems for practitioners and their patients and seem to be increasing in frequency and geographic distribution. Resistance to preventative therapies (macrocyclic lactones) complicates the picture. The use of chemotherapy for other kinds of pathogens has benefitted enormously from research into the basic biology of the pathogen and on the host-pathogen interface. A lack of basic information on heartworms as parasites and how they interact with permissive and non-permissive hosts greatly limits the ability to discover new ways to prevent and treat heartworm disease. Recent advances in technical platforms will help overcome the intrinsic barriers that hamper research on D. immitis, most notably, the need for experimentally infected dogs to maintain the life cycle and provide material for experiments. Impressive achievements in the development of laboratory animal models for D. immitis will enhance efforts to discover new drugs for prevention or treatment, to characterize new diagnostic biomarkers and to identify key parasite-derived molecules that are essential for survival in permissive hosts, providing a rational basis for vaccine discovery. A 'genomics toolbox' for D. immitis could enable unprecedented insight into the negotiations between host and parasite that enable survival in a permissive host. The more we know about the pathogen and how it manipulates its host, the better able we will be to protect companion animals far into the future.
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Affiliation(s)
- Timothy G Geary
- Institute of Parasitology, McGill University, Ste-Anne-de-Bellevue, QC, Canada.
- School of Biological Sciences, Queen's University-Belfast, Belfast, Northern Ireland.
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15
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Duncan K, Barrett AW, Little SE, Sundstrom KD, Guerino F. Fluralaner (Bravecto ®) treatment kills Aedes aegypti after feeding on Dirofilaria immitis-infected dogs. Parasit Vectors 2023; 16:208. [PMID: 37340454 DOI: 10.1186/s13071-023-05819-9] [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: 04/19/2023] [Accepted: 05/26/2023] [Indexed: 06/22/2023] Open
Abstract
BACKGROUND Transmission of canine heartworm (Dirofilaria immitis) from infected to naïve dogs is dependent on successful mosquito feeding and survival. METHODS To determine whether treating heartworm-infected dogs with fluralaner (Bravecto®) limits the survival of infected mosquitoes, and potentially the transmission of D. immitis, we allowed female mosquitoes to feed on microfilaremic dogs and evaluated mosquito survival and infection with D. immitis. Eight dogs were experimentally infected with D. immitis. On day 0 (~ 11 months post-infection), four microfilaremic dogs were treated with fluralaner according to label directions while the other four were non-treated controls. Mosquitoes (Aedes aegypti Liverpool) were allowed to feed on each dog on days -7, 2, 30, 56, and 84. Fed mosquitoes were collected, and the number of live mosquitoes determined at 6 h, 24 h, 48 h, and 72 h post-feeding. Surviving mosquitoes held for 2 weeks were dissected to confirm third-stage D. immitis larvae; PCR (12S rRNA gene) was performed post-dissection to identify D. immitis in mosquitoes. RESULTS Prior to treatment, 98.4%, 85.1%, 60.7%, and 40.3% of mosquitoes fed on microfilaremic dogs were alive at 6 h, 24 h, 48 h, and 72 h post-feeding, respectively. Similarly, mosquitoes fed on microfilaremic, non-treated dogs were alive 6 h post-feeding (98.5-100%) throughout the study. In contrast, mosquitoes fed on fluralaner-treated dogs 2 days after treatment were dead or severely moribund by 6 h post-feeding. At 30 and 56 days post-treatment, > 99% of mosquitoes fed on treated dogs were dead by 24 h. At 84 days post-treatment, 98.4% of mosquitoes fed on treated dogs were dead by 24 h. Before treatment, third-stage larvae of D. immitis were recovered from 15.5% of Ae. aegypti 2 weeks after feeding, and 72.4% were positive for D. immitis by PCR. Similarly, 17.7% of mosquitoes fed on non-treated dogs had D. immitis third-stage larvae 2 weeks after feeding, and 88.2% were positive by PCR. Five mosquitoes fed on fluralaner-treated dogs survived 2 weeks post-feeding, and 4/5 were from day 84. None had third-stage larvae at dissection, and all were PCR-negative. CONCLUSION The data indicate that fluralaner treatment of dogs kills mosquitoes and thus would be expected to reduce transmission of heartworm in the surrounding community.
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Affiliation(s)
- Kathryn Duncan
- Merck Animal Health, Rahway, NJ, USA.
- College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, USA.
| | | | - Susan E Little
- College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, USA
| | - Kellee D Sundstrom
- College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, USA
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16
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Evans CC, Normile D, Gamble S, Guerino F, Dzimianski MT, Moorhead AR. Treatment of dogs with Bravecto ® (fluralaner) reduces mosquito survival and fecundity. Parasit Vectors 2023; 16:147. [PMID: 37106394 PMCID: PMC10142166 DOI: 10.1186/s13071-023-05682-8] [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: 11/28/2022] [Accepted: 01/21/2023] [Indexed: 04/29/2023] Open
Abstract
BACKGROUND Mosquitoes serve as the vector of canine heartworm (Dirofilaria immitis), which represents a significant and persistent threat to canine health. A reduction in the longevity and/or reproductive success of mosquitoes that take a blood meal from fluralaner-treated dogs may consequently reduce the local transmission of heartworm and prevent new infections. A novel secondary effect of an oral formulation of the ectoparasiticide fluralaner (Bravecto®) against a laboratory strain of the mosquito Aedes aegypti, a potential major vector of canine heartworm, was investigated in this study. METHODS Six dogs were administered a single dose of fluralaner orally in the form of Bravecto® Chews (at the labeled fluralaner dose of 25 mg/kg body weight), while six control dogs received no treatment. Mosquitoes were fed on blood that was collected from each dog prior to treatment and weekly for 15 weeks post-treatment to assess the continued effects of fluralaner as its serum level decreased. Mosquito fitness was assessed by three parameters: rate of successful blood-feeding, survival, and egg laying. RESULTS Successful blood-feeding rate was similar between control and treatment groups. In the fluralaner treatment, mosquito survival was significantly reduced within the first 24 h after blood-feeding, for the first 12 weeks post-treatment of the dogs (efficacy range = 33.2-73.3%). Survival of mosquitoes up until a potentially heartworm-infective timepoint (14 days post-blood-feeding) was significantly reduced in the fluralaner-treated group at several timepoints (1, 2, 5, 11, 12, 13, 14, and 15 weeks post-treatment; efficacy range = 49.4-91.4%), but was less consistently reduced at the other timepoints. Egg laying by mosquitoes was almost completely suppressed for the first 13 weeks following treatment of the dogs with fluralaner (treatment efficacy ≥ 99.8%). CONCLUSIONS Mosquitoes fed blood from fluralaner-treated dogs experienced a significant reduction in survival and fecundity. These findings support the potential for a reduction in heartworm transmission directly by lethal effects on the vector and indirectly through a reduction of the local vector population when mosquitoes are exposed to animals treated with fluralaner.
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Affiliation(s)
- Christopher Charles Evans
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
| | | | | | | | - Michael T Dzimianski
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Andrew Riddell Moorhead
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
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17
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Thorn CS, Maness RW, Hulke JM, Delmore KE, Criscione CD. Population genomics of helminth parasites. J Helminthol 2023; 97:e29. [PMID: 36927601 DOI: 10.1017/s0022149x23000123] [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] [Indexed: 03/18/2023]
Abstract
Next generation sequencing technologies have facilitated a shift from a few targeted loci in population genetic studies to whole genome approaches. Here, we review the types of questions and inferences regarding the population biology and evolution of parasitic helminths being addressed within the field of population genomics. Topics include parabiome, hybridization, population structure, loci under selection and linkage mapping. We highlight various advances, and note the current trends in the field, particularly a focus on human-related parasites despite the inherent biodiversity of helminth species. We conclude by advocating for a broader application of population genomics to reflect the taxonomic and life history breadth displayed by helminth parasites. As such, our basic knowledge about helminth population biology and evolution would be enhanced while the diversity of helminths in itself would facilitate population genomic comparative studies to address broader ecological and evolutionary concepts.
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Affiliation(s)
- C S Thorn
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
| | - R W Maness
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
| | - J M Hulke
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
| | - K E Delmore
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
| | - C D Criscione
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
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18
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Constantinoiu C, Croton C, Paterson MBA, Knott L, Henning J, Mallyon J, Coleman GT. Prevalence of canine heartworm infection in Queensland, Australia: comparison of diagnostic methods and investigation of factors associated with reduction in antigen detection. Parasit Vectors 2023; 16:63. [PMID: 36765417 PMCID: PMC9921331 DOI: 10.1186/s13071-022-05633-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 12/22/2022] [Indexed: 02/12/2023] Open
Abstract
BACKGROUND The prevalence of Dirofilaria immitis infection in dogs is increasing globally and spreading into new areas. Prevalence of dirofilariosis in the state of Queensland, Australia, was as high as 90% before the introduction of macrocyclic lactones. Limited research on prevalence of D. immitis infection in dogs in Queensland has been reported in the last 30 years. Antigen testing is the most common method for detection of dirofilariosis but its accuracy is reduced by antigen getting trapped (blocked antigen) in immune complexes (ICs). The objectives of this research were to determine the prevalence of D. immitis infection in dogs from two geographical areas (Brisbane and Townsville) in Queensland, to determine the extent to which blocked antigen affects the validity of antigen testing, and to explore whether this was associated with microfilaraemia, location, age or sex. METHODS Blood samples from Brisbane (sub-tropical climate) and Townsville (tropical climate) shelter dogs were evaluated for the presence of D. immitis antigen before (conventional antigen testing, CAT) and after dissociation of ICs by heat treatment (antigen testing after heat treatment, ATHT), using a commercially available test. Microfilariae were detected using modified Knott's test (MKT). Test proportions were compared with McNemar's test and the association between antigen test-discordant results (positive for antigen after dissociation of ICs) and microfilaraemia, location, sex and age was modelled using logistic regression. RESULTS Dirofilaria immitis prevalence in dogs from Townsville (22% by CAT, 32.1% by ATHT and 16.7% by MKT) was significantly higher than in dogs from Brisbane (1.1% by CAT and MKT and 1.7% by ATHT) [Formula: see text]. Dissociation of ICs allowed detection of significantly more D. immitis infected dogs than either conventional antigen testing or microfilariae detection, or the combined antigen and microfilariae detection [Formula: see text]. The odds of dogs being positive for antigen after dissociation of ICs were significantly higher for microfilaraemic, 3-4-year-old female dogs from Townsville. CONCLUSIONS The high prevalence of infection with D. immitis in dogs from Townsville poses a health risk for local susceptible host species, including humans. Dissociation of ICs increases antigen detection and should be considered in dogs suspected of D. immitis infection but negative on routine testing.
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Affiliation(s)
| | - Catriona Croton
- University of Southern Queensland, Toowoomba, QLD Australia
- The University of Queensland, Gatton, QLD Australia
| | - Mandy B. A. Paterson
- Royal Society for the Prevention of Cruelty to Animals, Brisbane, QLD Australia
- The University of Queensland, Gatton, QLD Australia
| | - Lyn Knott
- The University of Queensland, Gatton, QLD Australia
| | - Joerg Henning
- University of Southern Queensland, Toowoomba, QLD Australia
- The University of Queensland, Gatton, QLD Australia
| | - John Mallyon
- The University of Queensland, Gatton, QLD Australia
| | - Glen T. Coleman
- University of Southern Queensland, Toowoomba, QLD Australia
- The University of Queensland, Gatton, QLD Australia
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Hess JA, Eberhard ML, Segura-Lepe M, Grundner-Culemann K, Kracher B, Shryock J, Harrington J, Abraham D. A rodent model for Dirofilaria immitis, canine heartworm: parasite growth, development, and drug sensitivity in NSG mice. Sci Rep 2023; 13:976. [PMID: 36653420 PMCID: PMC9849205 DOI: 10.1038/s41598-023-27537-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 01/04/2023] [Indexed: 01/19/2023] Open
Abstract
Heartworm disease, caused by Dirofilaria immitis, remains a significant threat to canines and felines. The development of parasites resistant to macrocyclic lactones (ML) has created a significant challenge to the control of the infection. The goal of this study was to determine if mice lacking a functional immune response would be susceptible to D. immitis. Immunodeficient NSG mice were susceptible to the infection, sustaining parasites for at least 15 weeks, with infective third-stage larvae molting and developing into the late fourth-stage larvae. Proteomic analysis of host responses to the infection revealed a complex pattern of changes after infection, with at least some of the responses directed at reducing immune control mechanisms that remain in NSG mice. NSG mice were infected with isolates of D. immitis that were either susceptible or resistant to MLs, as a population. The susceptible isolate was killed by ivermectin whereas the resistant isolate had improved survivability, while both isolates were affected by moxidectin. It was concluded that D. immitis survives in NSG mice for at least 15 weeks. NSG mice provide an ideal model for monitoring host responses to the infection and for testing parasites in vivo for susceptibility to direct chemotherapeutic activity of new agents.
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Affiliation(s)
- Jessica A Hess
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | | | | | | | | | - Jeffrey Shryock
- Boehringer Ingelheim Animal Health USA Inc., 6498 Jade Road, Fulton, MO, USA
| | - John Harrington
- Boehringer Ingelheim Animal Health USA Inc., 1730 Olympic Dr, Athens, GA, USA
| | - David Abraham
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
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Curry E, Prichard R, Lespine A. Genetic polymorphism, constitutive expression and tissue localization of Dirofilaria immitis P-glycoprotein 11: a putative marker of macrocyclic lactone resistance. Parasit Vectors 2022; 15:482. [PMID: 36544229 PMCID: PMC9773537 DOI: 10.1186/s13071-022-05571-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 11/02/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Dirofilaria immitis causes dirofilariosis, a potentially fatal condition in canids. Dirofilaria infections can be prevented with a macrocyclic lactone (ML) prophylactic regimen. However, some D. immitis isolates have become resistant to MLs. Genetic changes on the P-glycoprotein 11 gene, encoding an ABCB transporter, have been linked to the ML-resistant phenotypes and have been proposed as markers of drug resistance. However, nothing is known about the expression and the localization of this transporter in D. immitis, despite its strong link to ML-resistant phenotypes. METHODS We examined the clinically validated D. immitis P-glycoprotein 11 (DimPgp-11) single nucleotide polymorphism (SNP) via MiSeq analysis in three ML-susceptible isolates (Missouri, MP3 and Yazoo) and two ML-resistant isolates (JYD-34 and Metairie), and correlated the data with previously published MiSeq results of USA laboratory-maintained D. immitis isolates. The level of the expression of the DimPgp-11 messenger RNA transcript was analyzed by droplet digital PCR (ddPCR) and compared in the USA laboratory-maintained isolates, namely the ML-susceptible Missouri and Berkeley isolates, the putative ML-susceptible Georgia III and Big Head isolates and the ML-resistant isolate JYD-34. The immunolocalization of DimPgp-11 was visualized in the microfilaria (mf) life stage of the Missouri isolate using confocal microscopy. RESULTS The results confirmed that the SNP found on DimPgp-11 is differentially expressed in the USA laboratory-maintained isolates. The ML-susceptible isolates had an alternate allele frequency of between 0% and 15%, while it ranged between 17% and 56% in the ML-resistant isolates. The constitutive expression of DimPgp-11 was similar in the Berkeley, Georgia III and Big Head isolates, while it was significantly decreased in the ML-resistant JYD-34 isolate (P < 0.05), when compared to the ML-susceptible Missouri isolate. The DimPgp-11 protein was distinctly localized within the excretory-secretory (ES) duct, pore cells and the excretory cell and, more faintly, along the mf body wall. CONCLUSION Our data confirm that genetic polymorphism of DimPgp-11 is associated with ML resistance in USA laboratory-maintained D. imminits isolates. A link between DimPgp-11 and ML resistance in D. immitis is further supported by the lower protein expression in the ML-resistant JYD-34 isolate when compared with the ML-susceptible Missouri isolate. Interestingly, DimPgp-11 is strategically located surrounding the ES pore where it could play an active role in ML efflux.
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Affiliation(s)
- Emily Curry
- grid.14709.3b0000 0004 1936 8649Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Montreal, QC Canada
| | - Roger Prichard
- grid.14709.3b0000 0004 1936 8649Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Montreal, QC Canada
| | - Anne Lespine
- grid.508721.9INTHERES, INRAE, ENVT, Université de Toulouse, 31027 Toulouse Cedex 3, France
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21
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Mitchell E, Tielemans E, McCall JW, Baker C, Martin E, Frost J, Yoon S, Fankhauser B. Efficacy for the prevention of heartworm disease in dogs of an oral combination of moxidectin, afoxolaner, and pyrantel pamoate. Res Vet Sci 2022. [DOI: 10.1016/j.rvsc.2022.11.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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22
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Power RI, Šlapeta J. Exploration of the sensitivity to macrocyclic lactones in the canine heartworm (Dirofilaria immitis) in Australia using phenotypic and genotypic approaches. Int J Parasitol Drugs Drug Resist 2022; 20:145-158. [PMID: 36417831 PMCID: PMC9772245 DOI: 10.1016/j.ijpddr.2022.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 11/08/2022] [Accepted: 11/08/2022] [Indexed: 11/18/2022]
Abstract
Canine heartworm disease is a potentially deadly cardiopulmonary disease caused by the mosquito-borne filarial nematode Dirofilaria immitis. In Australia, the administration of macrocyclic lactone (ML) drugs has successfully reduced the prevalence of D. immitis infection. However, the recent re-emergence of D. immitis in dogs in Queensland, Australia and the identification of ML-resistant isolates in the USA poses an important question of whether ML-resistance has emerged in this parasite in Australia. The aim of this study was to utilise phenotypic and genotypic approaches to examine the sensitivity to ML drugs in D. immitis in Australia. To do this, we surveyed 45 dogs from Queensland and New South Wales across 3 years (2019-2022) for the presence of D. immitis infection using an antigen test, quantitative Modified Knott's test, and qPCR targeting both D. immitis and the D. immitis symbiont Wolbachia. A phenotype observed by utilising sequential quantification of microfilariae for 23/45 dogs was coupled with genetic testing of filtered microfilariae for SNPs previously associated with ML-resistance in isolates from the USA. Sixteen (16/45) dogs tested positive for D. immitis infection despite reportedly receiving 'rigorous' heartworm prevention for 12 months prior to the study, according to the owners' assessment. The phenotype and genotypic assays in this study did not unequivocally demonstrate the presence of ML-resistant D. immitis in Australia. Although the failure of 16 dogs to reduce microfilaremia by >90% after ML treatment was considered a suspect phenotype of ML-resistance, no genotypic evidence was discovered using the genetic SNP analysis. The traditional quantitative Modified Knott's test can be substituted by qPCR targeting D. immitis or associated Wolbachia endosymbiont DNA for a more rapid measurement of microfilariae levels. More definitive phenotypic evidence of resistance is critically needed before the usefulness of SNPs for the detection of ML-resistance in Australia can be properly assessed.
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Affiliation(s)
- Rosemonde Isabella Power
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, New South Wales, 2006, Australia
| | - Jan Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, New South Wales, 2006, Australia,The University of Sydney Institute for Infectious Diseases, New South Wales, 2006, Australia,Corresponding author. Sydney School of Veterinary Science, Faculty of Science, University of Sydney, New South Wales, 2006, Australia.
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23
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Doyle SR, Laing R, Bartley D, Morrison A, Holroyd N, Maitland K, Antonopoulos A, Chaudhry U, Flis I, Howell S, McIntyre J, Gilleard JS, Tait A, Mable B, Kaplan R, Sargison N, Britton C, Berriman M, Devaney E, Cotton JA. Genomic landscape of drug response reveals mediators of anthelmintic resistance. Cell Rep 2022; 41:111522. [PMID: 36261007 PMCID: PMC9597552 DOI: 10.1016/j.celrep.2022.111522] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 07/11/2022] [Accepted: 09/26/2022] [Indexed: 11/18/2022] Open
Abstract
Like other pathogens, parasitic helminths can rapidly evolve resistance to drug treatment. Understanding the genetic basis of anthelmintic drug resistance in parasitic nematodes is key to tracking its spread and improving the efficacy and sustainability of parasite control. Here, we use an in vivo genetic cross between drug-susceptible and multi-drug-resistant strains of Haemonchus contortus in a natural host-parasite system to simultaneously map resistance loci for the three major classes of anthelmintics. This approach identifies new alleles for resistance to benzimidazoles and levamisole and implicates the transcription factor cky-1 in ivermectin resistance. This gene is within a locus under selection in ivermectin-resistant populations worldwide; expression analyses and functional validation using knockdown experiments support that cky-1 is associated with ivermectin survival. Our work demonstrates the feasibility of high-resolution forward genetics in a parasitic nematode and identifies variants for the development of molecular diagnostics to combat drug resistance in the field.
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Affiliation(s)
- Stephen R Doyle
- Wellcome Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, UK.
| | - Roz Laing
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK.
| | - David Bartley
- Moredun Research Institute, Penicuik, Midlothian EH26 0PZ, UK
| | - Alison Morrison
- Moredun Research Institute, Penicuik, Midlothian EH26 0PZ, UK
| | - Nancy Holroyd
- Wellcome Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, UK
| | - Kirsty Maitland
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Alistair Antonopoulos
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Umer Chaudhry
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Ilona Flis
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Sue Howell
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Jennifer McIntyre
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - John S Gilleard
- Department of Comparative Biology and Experimental Medicine, Host-Parasite Interactions Program, Faculty of Veterinary Medicine, University of Calgary, Calgary T2N 1N4, Canada
| | - Andy Tait
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Barbara Mable
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Ray Kaplan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Neil Sargison
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Collette Britton
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | | | - Eileen Devaney
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - James A Cotton
- Wellcome Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, UK
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Dirofilaria immitis: Genotyping Randomly Selected European Clinical Samples and USA Laboratory Isolates with Molecular Markers Associated with Macrocyclic Lactone Susceptibility and Resistance. Pathogens 2022; 11:pathogens11080934. [PMID: 36015054 PMCID: PMC9415351 DOI: 10.3390/pathogens11080934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/11/2022] [Accepted: 08/16/2022] [Indexed: 11/17/2022] Open
Abstract
Dirofilaria immitis is a parasitic nematode and causes dirofilariosis, a potentially fatal pulmonary infection which primarily infects canids. Dirofilariosis infections are controlled via prophylactic macrocyclic lactone (ML) regimens. Recent evidence has confirmed the development of ML-resistant isolates in the USA, which are genetically distinct from wildtype populations. Single nucleotide polymorphisms (SNP) associated with ML-resistant phenotypes were clinically validated in USA populations. In this study, 3 USA laboratory-maintained isolates (Berkeley, Georgia II, and WildCat) and 11 randomly selected European clinical samples from 7 hosts were analyzed. The samples tested were fresh microfilaria (mf) in blood or adult worms preserved in ethanol. The samples underwent MiSeq sequencing of the top 9 SNP associated with ML resistance. The results provide the first genotypic analysis of the three USA laboratory-maintained isolates and any European samples. The European clinical samples show no genomic evidence of ML resistance based on the 9 SNP. The early adoption of genotyping of clinical D. immitis samples could provide an early indication of the potential development of ML resistance and aid to distinguish clinical cases of heartworm infection due to ML resistance from those due to a lack compliance with the recommended treatments, as has been seen in North America.
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Gomes-de-Sá S, Barradas P, Queirós-Reis L, Matas IM, Amorim I, Cardoso L, Muñoz-Mérida A, Mesquita JR. De Novo Assembly of the Dirofilaria immitis Genome by Long-Read Nanopore-Based Sequencing Technology on an Adult Worm from a Canine Cardiopulmonary Dirofilariosis Case. Animals (Basel) 2022; 12:ani12111342. [PMID: 35681811 PMCID: PMC9179477 DOI: 10.3390/ani12111342] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/13/2022] [Accepted: 05/24/2022] [Indexed: 11/29/2022] Open
Abstract
Simple Summary Dirofilaria immitis is a zoonotic parasite that infects canids and other vertebrates. We expanded the use of long-read nanopore-based sequencing technology by performing genomic de novo assembly of a D. immitis specimen retrieved from a canine cardiopulmonary dirofilariasis case by using the ONT MinION platform. We also identified loci previously characterized as being associated to macrocyclic lactone resistance selection pressure. The identification of a resistant zoonotic parasite alerts for the overuse of macrocyclic lactone in the region. Abstract Dirofilaria immitis is a zoonotic parasitic nematode that infects domestic and wild canids, among its vertebrate hosts. The genetic analysis of D. immitis nowadays transcends the need for genetic taxonomy of nematodes, such as the study of resistance to macrocyclic lactone. We expanded the use of long-read nanopore-based sequencing technology on nematodes by performing genomic de novo assembly of a D. immitis specimen retrieved from a canine cardiopulmonary dirofilariasis case using the ONT MinION platform, followed by the study of macrocyclic lactone resistance. The assembled genome of D. immitis consists of 110 contigs with an N50 of 3687191. The genome size is 87899012 and contains a total of 9741 proteins; 6 ribosomal RNAs, with three belonging to the small subunit (18S) and three to the large subunit (28S); and 73 tRNAs. Subsequent analysis of six loci previously characterized as being associated to macrocyclic lactone resistance selection pressure showed that four have a genotype associated with either some loss of efficacy or the resistance phenotype. Considering the zoonotic potential of D. immitis, the identification of a resistant parasite alerts for the overuse of macrocyclic lactone in the region, which poses a potential risk to both veterinary and human public health.
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Affiliation(s)
- Sónia Gomes-de-Sá
- ICBAS—School of Medicine and Biomedical Sciences, Porto University, 4050-313 Porto, Portugal; (S.G.-d.-S.); (L.Q.-R.); (I.A.)
| | - Patrícia Barradas
- Epidemiology Research Unit (EPIUnit), Instituto de Saúde Pública da Universidade do Porto, 4050-600 Porto, Portugal;
- Laboratório para a Investigação Integrativa e Translacional em Saúde Populacional (ITR), 4050-600 Porto, Portugal
- Department of Sciences, University Institute of Health Sciences (IUCS), CESPU, CRL, 4585-116 Gandra, Portugal
| | - Luís Queirós-Reis
- ICBAS—School of Medicine and Biomedical Sciences, Porto University, 4050-313 Porto, Portugal; (S.G.-d.-S.); (L.Q.-R.); (I.A.)
- Epidemiology Research Unit (EPIUnit), Instituto de Saúde Pública da Universidade do Porto, 4050-600 Porto, Portugal;
- Laboratório para a Investigação Integrativa e Translacional em Saúde Populacional (ITR), 4050-600 Porto, Portugal
| | - Isabel M. Matas
- Centro de Investigação em Biodiversidade e Recursos Genéticos (CIBIO/InBIO), Universidade do Porto, Vairão, 4485-661 Porto, Portugal; (I.M.M.); (A.M.-M.)
| | - Irina Amorim
- ICBAS—School of Medicine and Biomedical Sciences, Porto University, 4050-313 Porto, Portugal; (S.G.-d.-S.); (L.Q.-R.); (I.A.)
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), 4220-135 Porto, Portugal
- Institute for Research and Innovation in Health (i3S), University of Porto, 4200-135 Porto, Portugal
| | - Luís Cardoso
- Department of Veterinary Sciences, School of Agrarian and Veterinary Sciences, University of Trás-os-Montes e Alto Douro (UTAD), 5000-801 Vila Real, Portugal;
- Animal and Veterinary Research Centre (CECAV), UTAD, 5000-801 Vila Real, Portugal
| | - Antonio Muñoz-Mérida
- Centro de Investigação em Biodiversidade e Recursos Genéticos (CIBIO/InBIO), Universidade do Porto, Vairão, 4485-661 Porto, Portugal; (I.M.M.); (A.M.-M.)
| | - João R. Mesquita
- ICBAS—School of Medicine and Biomedical Sciences, Porto University, 4050-313 Porto, Portugal; (S.G.-d.-S.); (L.Q.-R.); (I.A.)
- Epidemiology Research Unit (EPIUnit), Instituto de Saúde Pública da Universidade do Porto, 4050-600 Porto, Portugal;
- Laboratório para a Investigação Integrativa e Translacional em Saúde Populacional (ITR), 4050-600 Porto, Portugal
- Correspondence:
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Airs PM, Vaccaro K, Gallo KJ, Dinguirard N, Heimark ZW, Wheeler NJ, He J, Weiss KR, Schroeder NE, Huisken J, Zamanian M. Spatial transcriptomics reveals antiparasitic targets associated with essential behaviors in the human parasite Brugia malayi. PLoS Pathog 2022; 18:e1010399. [PMID: 35390105 PMCID: PMC9017939 DOI: 10.1371/journal.ppat.1010399] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 04/19/2022] [Accepted: 02/25/2022] [Indexed: 01/24/2023] Open
Abstract
Lymphatic filariasis (LF) is a chronic debilitating neglected tropical disease (NTD) caused by mosquito-transmitted nematodes that afflicts over 60 million people. Control of LF relies on routine mass drug administration with antiparasitics that clear circulating larval parasites but are ineffective against adults. The development of effective adulticides is hampered by a poor understanding of the processes and tissues driving parasite survival in the host. The adult filariae head region contains essential tissues that control parasite feeding, sensory, secretory, and reproductive behaviors, which express promising molecular substrates for the development of antifilarial drugs, vaccines, and diagnostics. We have adapted spatial transcriptomic approaches to map gene expression patterns across these prioritized but historically intractable head tissues. Spatial and tissue-resolved data reveal distinct biases in the origins of known drug targets and secreted antigens. These data were used to identify potential new drug and vaccine targets, including putative hidden antigens expressed in the alimentary canal, and to spatially associate receptor subunits belonging to druggable families. Spatial transcriptomic approaches provide a powerful resource to aid gene function inference and seed antiparasitic discovery pipelines across helminths of relevance to human and animal health.
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Affiliation(s)
- Paul M. Airs
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Kathy Vaccaro
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Kendra J. Gallo
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Nathalie Dinguirard
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Zachary W. Heimark
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Nicolas J. Wheeler
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Jiaye He
- Morgridge Institute for Research, Madison, Wisconsin, United States of America
| | - Kurt R. Weiss
- Morgridge Institute for Research, Madison, Wisconsin, United States of America
| | - Nathan E. Schroeder
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Jan Huisken
- Morgridge Institute for Research, Madison, Wisconsin, United States of America
- Department of Integrative Biology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Mostafa Zamanian
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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27
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Myers JAE, Holzmer S, McCall JW, Mahabir SP, McTier TL, Maeder SJ, Kryda K. Preventive efficacy of six monthly oral doses of Simparica Trio ®, Heartgard ® Plus, and Interceptor ® Plus against a macrocyclic lactone-resistant strain (ZoeLA) of heartworm (Dirofilaria immitis) in dogs. Parasit Vectors 2022; 15:81. [PMID: 35277191 PMCID: PMC8915520 DOI: 10.1186/s13071-022-05180-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/25/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Administration of four to six consecutive monthly doses of 24 µg/kg moxidectin alone shows high effectiveness in preventing the maturation of macrocyclic lactone (ML)-resistant heartworm strains, Dirofilaria immitis JYD-34 and ZoeLA. This laboratory study evaluated the efficacy of six consecutive monthly oral doses of Simparica Trio® (moxidectin/sarolaner/pyrantel) compared to six monthly doses of either Heartgard® Plus (ivermectin/pyrantel) or Interceptor® Plus (milbemycin oxime/praziquantel) against ML-resistant D. immitis ZoeLA strain. METHODS Beagle dogs were inoculated with 50 third-stage (L3) D. immitis larvae (ZoeLA) 30 days prior to the first treatment. Dogs were randomized to treatment (six animals in each group) with six monthly oral doses of placebo, Simparica Trio, Heartgard Plus, or Interceptor Plus at their respective label doses. Microfilaria (MF) and antigen tests were conducted periodically, and efficacy was evaluated by necropsy for adult heartworms approximately 9 months after L3 inoculation. RESULTS Adult heartworms were recovered from all six placebo dogs, with a geometric mean of 35.5 worms (range, 23-48). Five of the six dogs treated with Simparica Trio were infected with a geometric mean of 1.0 worms (range, 0-3), and all remained MF-negative. All Heartgard Plus-treated dogs (six) were infected with a geometric mean of 32.5 worms (range, 22-38); five of these dogs were MF-positive at day 236. All Interceptor Plus-treated dogs (six) were infected with a geometric mean of 22.8 worms (range, 10-34); five of these dogs were MF-positive at day 236. The efficacy of six consecutive doses with Simparica Trio, Heartgard Plus, and Interceptor Plus against ZoeLA was 97.2, 8.5, and 35.9%, respectively. Adult worm counts for the Simparica Trio-treated group were significantly lower (P < 0.0001) than placebo control, Heartgard Plus, and Interceptor Plus-treated groups. Adult worm counts for Heartgard Plus and Interceptor Plus were not significantly different from placebo (P > 0.05). CONCLUSIONS Simparica Trio prevented microfilaremia in all dogs and was highly effective (97.2%) and significantly better than either Heartgard Plus (8.5%) or Interceptor Plus (35.9%) in preventing the development of the ZoeLA ML-resistant heartworm strain when administered for six consecutive months in this comparative laboratory efficacy study.
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Affiliation(s)
- Jamie A E Myers
- Zoetis, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA.
| | - Susan Holzmer
- Zoetis, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA
| | - John W McCall
- TRS Labs Inc, 215 Paradise Blvd, Athens, GA, 30607, USA
| | - Sean P Mahabir
- Zoetis, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA
| | - Tom L McTier
- Zoetis, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA
| | - Steven J Maeder
- Zoetis, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA
| | - Kristina Kryda
- Zoetis, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA
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Savadelis MD, McTier TL, Kryda K, Maeder SJ, Woods DJ. Moxidectin: heartworm disease prevention in dogs in the face of emerging macrocyclic lactone resistance. Parasit Vectors 2022; 15:82. [PMID: 35277180 PMCID: PMC8915515 DOI: 10.1186/s13071-021-05104-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 11/18/2021] [Indexed: 12/04/2022] Open
Abstract
Heartworm (Dirofilaria immitis) disease continues to increase and spread, remaining one of the most important and pathogenic parasitic diseases of dogs, despite the regular use of macrocyclic lactones (MLs) in preventive products. Dogs harboring strains of D. immitis resistant to MLs, the only drug class available for heartworm prevention in the United States, have been documented and proven. As no new products are available utilizing a novel drug class for the prevention of this disease, the only options for combating ML resistance include increasing the dose and/or changing the dosage regime of current MLs, or by optimizing the formulations of MLs currently available. Moxidectin provides a unique opportunity for optimization of the dose and formulation, which may provide improved efficacy against ML-resistant strains. Currently there are oral, topical, and injectable moxidectin products approved for heartworm prevention in the USA. Two new products (ProHeart® 12 and Simparica Trio®), available in many countries around the world including the USA, take advantage of the unique attributes of moxidectin for providing robust heartworm prevention against the strains of heartworm to which most dogs in the USA will likely be exposed. Both products have demonstrated 100% preventive efficacy in laboratory studies against recently collected field strains of heartworm, and also in large field studies, where the majority of dogs were living in the southern USA in areas where ML resistance has been confirmed to occur, therefore under elevated heartworm challenge. Based on the data summarized here, these products offer important advances in heartworm prevention and provide additional options for veterinarians and pet owners to protect their dogs from developing heartworm disease.
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29
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Curry E, Prichard R. Development of rapid in vitro colorimetric enzymatic activity assay to differentiate macrocyclic lactone susceptible and resistant Dirofilaria immitis isolates. Vet Parasitol 2022; 304:109696. [DOI: 10.1016/j.vetpar.2022.109696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/07/2022] [Accepted: 03/08/2022] [Indexed: 10/18/2022]
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Macrocyclic lactone resistance in Dirofilaria immitis: risks for prevention of heartworm disease. Int J Parasitol 2021; 51:1121-1132. [PMID: 34717929 DOI: 10.1016/j.ijpara.2021.08.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/29/2021] [Accepted: 08/31/2021] [Indexed: 11/21/2022]
Abstract
Heartworm disease, caused by Dirofilaria immitis, can be lethal in dogs and cats. It is transmitted by mosquitoes, and occurs in many parts of the world. Prevention relies on macrocyclic lactones. Macrocyclic lactones used are ivermectin, selamectin, abamectin, eprinomectin, milbemycin oxime and moxidectin, administered at 30-day intervals during the transmission season. Some moxidectin formulations are long-acting injectables. In the USA, preventives are recommended throughout the year. Loss of efficacy of macrocyclic lactone preventives was reported in 2005 and proof of resistance in the USA was published a decade later. Understanding factors which promote resistance is important to maintain control. Factors important for resistance development are discussed. Better, inexpensive tests to confirm resistance are needed. Infection in animals under chemoprophylaxis per se does not imply resistance because lack of compliance in preventive use could be the reason. In vivo confirmation of resistance is expensive, slow and ethically questionable. A microfilariae suppression test can be a surrogate test, but requires a high dose of a macrocyclic lactone and repeated blood microfilaria counts 2-4 weeks later. DNA single nucleotide polymorphism markers have been successfully used. However, the specific genetic changes which cause resistance are unknown. Surveys to map and follow the extent of resistance are needed. Long acting mosquito repellants and insecticides can play a useful role. High dose rate formulations of moxidectin, coupled with mosquito biting mitigation may reduce transmission of resistant genotypes. Doxycycline, daily for 28 days, as anti-Wolbachia treatment, can reduce transmission and remove adult parasites. However, new classes of heartworm preventives are needed. While any preventive strategy must be highly effective, registration requirements for 100% efficacy may hinder development of useful new classes of preventives. Continued reliance on macrocyclic lactone preventives, when they do not work against resistant genotypes, will spread resistance, and allow for more disease.
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Concern for Dirofilaria immitis and Macrocyclic Lactone Loss of Efficacy: Current Situation in the USA and Europe, and Future Scenarios. Pathogens 2021; 10:pathogens10101323. [PMID: 34684273 PMCID: PMC8541013 DOI: 10.3390/pathogens10101323] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/11/2021] [Accepted: 10/13/2021] [Indexed: 12/02/2022] Open
Abstract
Dirofilaria immitis infection is one of the most severe parasitic diseases in dogs. Prevention is achieved by the administration of drugs containing macrocyclic lactones (MLs). These products are very safe and highly effective, targeting the third and fourth larval stages (L3, L4) of the parasite. Until 2011, claims of the ineffectiveness of MLs, reported as “loss of efficacy” (LOE), were generally attributed to owners’ non-compliance, or other reasons associated with inadequate preventative coverage. There was solid argumentation that a resistance problem is not likely to occur because of (i) the great extent of refugia, (ii) the complexity of resistance development to MLs, and (iii) the possible large number of genes involved in resistance selection. Nevertheless, today, it is unequivocally proven that ML-resistant D. immitis strains exist, at least in the Lower Mississippi region, USA. Accordingly, tools have been developed to evaluate and confirm the susceptibility status of D. immitis strains. A simple, in-clinic, microfilariae suppression test, 14-28 days after ML administration, and a “decision tree” (algorithm), including compliance and preventatives’ purchase history, and testing gaps, may be applied for assessing any resistant nature of the parasite. On the molecular level, specific SNPs may be used as markers of ML resistance, offering a basis for the validation of clinically suspected resistant strains. In Europe, no LOE/resistance claims have been reported so far, and the existing conditions (stray dogs, rich wildlife, majority of owned dogs not on preventive ML treatment) do not favor selection pressure on the parasites. Considering the genetic basis of resistance and the epizootiological characteristics of D. immitis, ML resistance neither establishes easily nor spreads quickly, a fact confirmed by the current known dispersion of the problem, which is limited. Nevertheless, ML resistance may propagate from an initial geographical point, via animal and vector mobility, to other regions, while it can also emerge as an independent evolutionary process in a new area. For these reasons, and considering the current chemoprophylaxis recommendations and increasing use of ML endectoparasiticides as a potential selection pressure, it is important to remain vigilant for the timely detection of any ML LOE/resistance, in all continents where D. immitis is enzootic.
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Noack S, Harrington J, Carithers DS, Kaminsky R, Selzer PM. Heartworm disease - Overview, intervention, and industry perspective. Int J Parasitol Drugs Drug Resist 2021; 16:65-89. [PMID: 34030109 PMCID: PMC8163879 DOI: 10.1016/j.ijpddr.2021.03.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/26/2021] [Accepted: 03/30/2021] [Indexed: 02/06/2023]
Abstract
Dirofilaria immitis, also known as heartworm, is a major parasitic threat for dogs and cats around the world. Because of its impact on the health and welfare of companion animals, heartworm disease is of huge veterinary and economic importance especially in North America, Europe, Asia and Australia. Within the animal health market many different heartworm preventive products are available, all of which contain active components of the same drug class, the macrocyclic lactones. In addition to compliance issues, such as under-dosing or irregular treatment intervals, the occurrence of drug-resistant heartworms within the populations in the Mississippi River areas adds to the failure of preventive treatments. The objective of this review is to provide an overview of the disease, summarize the current disease control measures and highlight potential new avenues and best practices for treatment and prevention.
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Affiliation(s)
- Sandra Noack
- Boehringer Ingelheim Animal Health, Binger Str. 173, 55216, Ingelheim am Rhein, Germany
| | - John Harrington
- Boehringer Ingelheim Animal Health, 1730 Olympic Drive, 30601, Athens, GA, USA
| | - Douglas S Carithers
- Boehringer Ingelheim Animal Health, 3239 Satellite Blvd, 30096, Duluth, GA, USA
| | - Ronald Kaminsky
- paraC Consulting, Altenstein 13, 79685, Häg-Ehrsberg, Germany
| | - Paul M Selzer
- Boehringer Ingelheim Animal Health, Binger Str. 173, 55216, Ingelheim am Rhein, Germany.
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Jacobson LS, DiGangi BA. An Accessible Alternative to Melarsomine: "Moxi-Doxy" for Treatment of Adult Heartworm Infection in Dogs. Front Vet Sci 2021; 8:702018. [PMID: 34386540 PMCID: PMC8353148 DOI: 10.3389/fvets.2021.702018] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 06/30/2021] [Indexed: 11/29/2022] Open
Abstract
Canine heartworm infection, caused by the filarial parasite Dirofilaria immitis, represents a serious and expanding animal welfare concern that is expected to increase due to the effects of climate change and the COVID-19 pandemic. A body of evidence has emerged to support the use of a non-arsenical adulticide treatment protocol, using moxidectin and doxycycline to kill adult heartworms over a prolonged period. While a three-dose protocol using the arsenical drug melarsomine is currently the safest and most effective treatment for heartworm infection, this drug is not available in some countries and is inaccessible for many owners and animal shelters. Moxidectin-doxycycline (moxi-doxy) provides a viable alternative to no treatment at all, in cases where arsenical treatment is not possible. Based on current evidence, the most effective non-arsenical treatment regimen is doxycycline 10 mg/kg PO q 12 or 24 h for 28 days, combined with topical moxidectin at label dose. Moxidectin is repeated monthly until no antigen detected (NAD) status is confirmed. Sustained release injectable moxidectin, in combination with doxycycline, may provide an alternative in remote regions or in settings where significant compliance or accessibility concerns exist, but more studies are needed. In moxi-doxy protocols, doxycycline should be repeated annually until NAD. This review summarizes the safety and efficacy of moxi-doxy, addresses controversies surrounding this treatment approach, and provides detailed recommendations for treatment regimens and post-treatment testing.
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Affiliation(s)
- Linda S. Jacobson
- Shelter Medicine Advancement, Toronto Humane Society, Toronto, ON, Canada
| | - Brian A. DiGangi
- Shelter and Veterinary Services, American Society for the Prevention of Cruelty to Animals, New York, NY, United States
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Zinser EW, McTier TL, Kernell NS, Woods DJ. Cryogenic preservation of Dirofilaria immitis microfilariae, reactivation and completion of the life-cycle in the mosquito and vertebrate hosts. Parasit Vectors 2021; 14:367. [PMID: 34271978 PMCID: PMC8283926 DOI: 10.1186/s13071-021-04839-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 06/10/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The cryopreservation of filarial nematodes has been studied for nearly 70 years. Largely, these studies examined the effectiveness of cryopreservation methods by using the post-thaw survival of microfilariae (mf) and the development to third-stage larvae (L3s) following inoculation into a competent insect vector. Only one study reported complete reestablishment of a filarial nematode (Brugia malayi) life-cycle in a competent vertebrate host from cryopreserved stock. Expanding on this previous research, a cryopreservation method was developed to cryopreserve the mf of the dog heartworm, Dirofilaria immitis. METHODS A combination of cryoprotectants, dimethyl sulfoxide (DMSO) and polyvinyl pyrolidone (PVP) at 6% and 4 mM, respectively, provided acceptable post-thaw survival of mf that developed into L3s in Aedes aegypti. L3s developed from cryopreserved and freshly collected mf in mosquitoes were inoculated into ferrets and dogs and were assessed after a sufficient duration post-inoculation for development into adult heartworms. RESULTS Fewer adult heartworms derived from cryopreserved stocks of mf were recovered from ferrets compared to adult heartworms derived from freshly collected mf, and the former were smaller by weight and length. The onset of patency (circulating mf) occurred at similar post-inoculation time points and at similar mf densities in dogs infected with L3s sourced from cryopreserved stocks or freshly collected mf. Adults derived from cryopreserved mf have survived and produced viable mf for more than 3 years in dogs. Approximately 60% of inoculated L3s were recovered as adults from dogs at 2 and 3.5 years post-inoculation. CONCLUSIONS The results from these direct comparisons demonstrate that cryopreserved mf can develop into L3s in vector mosquitoes and that these L3s are infective to both dogs and ferrets, where they undergo normal development into adult worms. These worms are able to mate and produce viable mf and complete the heartworm lifecycle in dog.
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Affiliation(s)
- Erich W Zinser
- Zoetis, Veterinary Medicine Research and Development, 333 Portage St, Kalamazoo, MI, 49007, USA.
| | - Tom L McTier
- Zoetis, Veterinary Medicine Research and Development, 333 Portage St, Kalamazoo, MI, 49007, USA
| | - Nicole S Kernell
- Zoetis, Veterinary Medicine Research and Development, 333 Portage St, Kalamazoo, MI, 49007, USA
| | - Debra J Woods
- Zoetis, Veterinary Medicine Research and Development, 333 Portage St, Kalamazoo, MI, 49007, USA
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Abstract
The goal of preventive care is to maintain and optimize health by averting preventable problems. Effective preventive care programs for working dogs must incorporate standard procedures applicable to dogs in general with additional elements pertinent to the more specific characteristics of breed, geographic location, living and working conditions, and physical and mental tasks required of the working dog. This article covers the basic essential preventive health guidelines for all working dogs as well as the specific breed, occupational, and regional considerations to be taken into account.
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Affiliation(s)
- Marcella Ridgway
- College of Veterinary Medicine, University of Illinois, Urbana, IL 61802, USA.
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Young LM, Wiseman S, Crawley E, Wallace K, Snyder DE. Field study to investigate the effectiveness and safety of a novel orally administered combination drug product containing milbemycin oxime and lotilaner (Credelio ® Plus) for the prevention of heartworm disease (Dirofilaria immitis) in client-owned dogs in the USA. Parasit Vectors 2021; 14:284. [PMID: 34044864 PMCID: PMC8161898 DOI: 10.1186/s13071-021-04767-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 05/03/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Dirofilaria immitis, a globally distributed filarial parasite of dogs, is known to cause serious or fatal cardiopulmonary disease. Client-owned dogs were enrolled in a clinical field study in the USA to evaluate the clinical effectiveness and field safety of an orally administered combination investigational product (IP) containing milbemycin oxime and lotilaner (Credelio® Plus) as compared to a control product (CP) for the prevention of heartworm disease when administered monthly for 11 consecutive months. METHODS In this 11-month field study, 319 dogs ≥ 8 weeks old confirmed to be heartworm-negative were enrolled from eight geographically distinct US veterinary clinics, including sites in the southern USA and Mississippi River Valley. The dogs were treated with either the IP combination product at 0.75-1.53 mg/kg milbemycin oxime and 20-41.5 mg/kg lotilaner (n = 159) or the CP (Sentinel® Flavor Tabs®; milbemycin oxime/lufenuron) at the label-recommended dose rate (n = 158.) On day 330, effectiveness was evaluated in each dog using antigen and microfilarial (modified Knott's) testing to assess the establishment of any patent adult heartworm infections. RESULTS All dogs treated with the IP combination product and the CP tested negative (100% prevention) for heartworm infection on day 330. The IP combination product tablets containing milbemycin oxime and lotilaner were well tolerated based on the safety assessments in all treated dogs. CONCLUSIONS This multi-site clinical study using client-owned dogs demonstrated that monthly use of flavored, chewable tablets containing a combination of milbemycin oxime and lotilaner administered orally under end use conditions is safe for dogs. None of the enrolled dogs developed heartworm infections. Eleven consecutive monthly treatments of the IP provided 100% prevention of heartworm disease caused by D. immitis.
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Affiliation(s)
- Lisa M Young
- Elanco Animal Health Research and Development, 2500 Innovation Way, Greenfield, IN, 46140, USA
| | - Scott Wiseman
- Elanco Animal Health, Form 2, Bartley Way, Bartley Wood Business Park, Hook, RG27 9XA, Hants, UK
| | - Elizabeth Crawley
- Elanco Animal Health Research and Development, 2500 Innovation Way, Greenfield, IN, 46140, USA
| | - Kim Wallace
- Elanco Animal Health Research and Development, 2500 Innovation Way, Greenfield, IN, 46140, USA
| | - Daniel E Snyder
- Daniel E. Snyder, DVM PhD. Consulting, LLC, Indianapolis, IN, 46229, USA.
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Ta-Tang TH, Luz SLB, Crainey JL, Rubio JM. An Overview of the Management of Mansonellosis. Res Rep Trop Med 2021; 12:93-105. [PMID: 34079424 PMCID: PMC8163967 DOI: 10.2147/rrtm.s274684] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 04/30/2021] [Indexed: 02/02/2023] Open
Abstract
Mansonellosis is caused by three filarial parasite species from the genus Mansonella that commonly produce chronic human microfilaraemias: M. ozzardi, M. perstans and M. streptocerca. The disease is widespread in Africa, the Caribbean and South and Central America, and although it is typically asymptomatic it has been associated with mild pathologies including leg-chills, joint-pains, headaches, fevers, and corneal lesions. No robust mansonellosis disease burden estimates have yet been made and the impact the disease has on blood bank stocks and the monitoring of other filarial diseases is not thought to be of sufficient public health importance to justify dedicated disease management interventions. Mansonellosis´s Ceratopogonidae and Simuliidae vectors are not targeted by other control programmes and because of their small size and out-door biting habits are unlikely to be affected by interventions targeting other disease vectors like mosquitoes. The ivermectin and mebendazole-based mass drug administration (iMDA and mMDA) treatment regimens deployed by the WHO´s Elimination of Neglected Tropical Diseases (ESPEN) programme and its forerunners have, however, likely impacted significantly on the mansonellosis disease burden, principally by reducing the transmission of M. streptocerca in Africa. The increasingly popular plan of using iMDA to control malaria could also affect M. ozzardi parasite prevalence and transmission in Latin America in the future. However, a potentially far greater mansonellosis disease burden impact is likely to come from short-course curative anti-Wolbachia therapeutics, which are presently being developed for onchocerciasis and lymphatic filariasis treatment. Even if the WHO´s ESPEN programme does not choose to deploy these drugs in MDA interventions, they have the potential to dramatically increase the financial and logistical feasibility of effective mansonellosis management. There is, thus, now a fresh and urgent need to better characterise the disease burden and eco-epidemiology of mansonellosis so that effective management programmes can be designed, advocated for and implemented.
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Affiliation(s)
- Thuy-Huong Ta-Tang
- Malaria and NTDs Laboratory, National Centre of Tropical Medicine, Instituto de Salud Carlos III, Madrid, Spain
| | - Sergio L B Luz
- Laboratório de Ecologia de Doenças Transmissíveis na Amazônia, Instituto Leônidas e Maria Deane, Fundação Oswaldo Cruz, Manaus, Amazonas State, Brazil
| | - James L Crainey
- Laboratório de Ecologia de Doenças Transmissíveis na Amazônia, Instituto Leônidas e Maria Deane, Fundação Oswaldo Cruz, Manaus, Amazonas State, Brazil
| | - José M Rubio
- Malaria & Emerging Parasitic Diseases Laboratory, National Microbiology Center, Instituto de Salud Carlos III, Madrid, Spain
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McTier TL, Holzmer S, Kryda K, Mahabir S, McCall JW, Trombley J, Maeder SJ. Comparative preventive efficacy of ProHeart ® 12, Heartgard ® Plus and Interceptor ® Plus against a macrocyclic lactone-resistant strain (JYD-34) of heartworm (Dirofilaria immitis) in dogs. Parasit Vectors 2021; 14:226. [PMID: 33902689 PMCID: PMC8074443 DOI: 10.1186/s13071-021-04708-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 03/31/2021] [Indexed: 11/21/2022] Open
Abstract
Background The current studies compared ProHeart® 12, Heartgard® Plus and Interceptor® Plus for preventive efficacy against JYD-34, a macrocyclic lactone (ML)-resistant strain of Dirofilaria immitis in dogs. Methods In two studies, each using 24 adult beagles, dogs were allocated to four treatment groups (n = 6): placebo-treated control; ProHeart 12 as per label (0.5 mg/kg moxidectin); Heartgard Plus (HGP) as per label (minimum 6 µg/kg ivermectin); and Interceptor Plus (INP) as per label (minimum 0.5 mg/kg milbemycin oxime). In both studies, ProHeart 12 was administered as a single subcutaneous dose on day 0, and HGP and INP were administered orally on days 0, 30, 60, 90, 120 and 150. In Studies 1 and 2, dogs were inoculated with 50 third-stage heartworm larvae (JYD-34 strain) on days −30 and 165, respectively. In Study 2, treatment for both HGP and INP was continued on days 180, 210, 240, 270, 300 and 330. Adult heartworm recoveries were performed on day 185 in Study 1 and on day 360 in Study 2. Results In Studies 1 and 2, all placebo-treated dogs developed adult heartworm infections (geometric mean, 29.9 and 34.9 worms/dog, respectively). A single dose of ProHeart 12 was 100% effective in preventing the development of adult JYD-34 heartworms when treatment was initiated 30 days after heartworm inoculation, while six consecutive monthly doses of HGP and INP were only 10.5% and 14.6% effective, respectively. The mean worm count for the ProHeart 12-treated group was significantly lower (P < 0.0001) than that for the placebo control, HGP- and INP-treated groups. In Study 2, the dogs treated with ProHeart 12 had an efficacy of 98.3%. All dogs treated with HGP and INP for 12 consecutive months had adult heartworms with efficacies of 37.7% and 34.9%, respectively. The mean worm count for the ProHeart 12-treated dogs was significantly lower (P < 0.0001) than those for the control group, HGP- and INP-treated groups. Conclusions A single administration of ProHeart 12 was 98–100% effective in preventing the development of the ML-resistant JYD-34 heartworm strain and was significantly better than multiple consecutive monthly doses of either Heartgard Plus or Interceptor Plus in both studies. Graphic Abstract ![]()
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Affiliation(s)
- Tom L McTier
- Veterinary Medicine Research and Development, 333 Portage St, Kalamazoo, MI, 49007, USA.
| | - Susan Holzmer
- Veterinary Medicine Research and Development, 333 Portage St, Kalamazoo, MI, 49007, USA
| | - Kristina Kryda
- Veterinary Medicine Research and Development, 333 Portage St, Kalamazoo, MI, 49007, USA
| | - Sean Mahabir
- Veterinary Medicine Research and Development, 333 Portage St, Kalamazoo, MI, 49007, USA
| | | | - Jami Trombley
- Northern Biomedical Research Inc, 1210 Pontaluna Road, Spring Lake, MI, USA
| | - Steven J Maeder
- Veterinary Medicine Research and Development, 333 Portage St, Kalamazoo, MI, 49007, USA
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Whole-genome reference of Dirofilaria immitis from Australia to determine single nucleotide polymorphisms associated with macrocyclic lactone resistance in the USA. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2021; 1:100007. [PMID: 35284873 PMCID: PMC8906102 DOI: 10.1016/j.crpvbd.2021.100007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/03/2021] [Accepted: 01/05/2021] [Indexed: 11/20/2022]
Abstract
For the past 30 years, chemoprophylaxis with macrocyclic lactone (ML) anthelmintics has been the primary strategy for canine heartworm (Dirofilaria immitis) control in both the USA and Australia. ML-resistant D. immitis isolates have been confirmed to exist in the USA and studies have shown that 42 single nucleotide polymorphisms (SNPs) are associated with phenotypic ML-resistance. Currently, ML-resistance has not been reported in any Australian clinical cases of canine heartworm. The aim of the study is to determine whether the 42 SNPs associated with resistance to MLs in the isolates from the USA are present in adult heartworms from a clinical case in Australia. Five adult D. immitis obtained from a dog at post-mortem (Sydney, Australia) were sequenced using the Illumina sequencing technology. The genomic analyses revealed 6 out of the 42 SNPs associated with ML-resistance to be present in our samples, 3 out of the 6 SNPs identified were nonsynonymous SNPs but not in candidate genes for ML-resistance. ML-susceptibility profile was mixed using the 42-SNP and 10-SNP models, but the 5-SNP, 3-SNP and 2-SNP models demonstrated ML susceptibility for all five individuals. In this study, the first whole-genome reference of D. immitis from Australia establishes a new baseline for comparative studies and will be valuable for tracking ML-resistance emergence. Dirofilaria immitis from Sydney, Australia, sequenced using the Illumina NGS technology. New baseline for comparative studies for tracking ML-resistance emergence in Australia. Mixed ML-susceptibility profile using the 42-SNP and 10-SNP models. 5-SNP, 3-SNP and 2-SNP models demonstrated ML susceptibility.
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Verma S, Kulke D, McCall JW, Martin RJ, Robertson AP. Recording drug responses from adult Dirofilaria immitis pharyngeal and somatic muscle cells. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2020; 15:1-8. [PMID: 33348209 PMCID: PMC7753077 DOI: 10.1016/j.ijpddr.2020.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 12/13/2022]
Abstract
Despite being considered one of the most pathogenic helminth infections of companion animals, members of macrocyclic lactone class are the only drugs available for the prevention of heartworm disease caused by Dirofilaria immitis. Alarmingly, heartworm prevention is at risk; several studies confirm the existence of macrocyclic lactone resistance in D. immitis populations across the United States. To safeguard the long term prevention and control of this disease, the identification and development of novel anthelmintics is urgently needed. To identify novel, resistance-breaking drugs, it is highly desirable to: Unfortunately, none of the three above statements can be answered sufficiently for D. immitis and most of our hypotheses derive from surrogate species and/or in vitro studies. Therefore, the present study aims to improve our fundamental understanding of the neuromuscular system of the canine heartworm by establishing new methods allowing the investigation of body wall and pharyngeal muscle responses and their modulation by anthelmintics. We found that the pharynx of adult D. immitis responds to both ivermectin and moxidectin with EC50s in the low micromolar range. We also demonstrate that the somatic muscle cells have robust responses to 30 μM acetylcholine, levamisole, pyrantel and nicotine. This is important preliminary data, demonstrating the feasibility of electrophysiological studies in this important parasite.
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Affiliation(s)
- S Verma
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
| | - D Kulke
- Drug Discovery and External Innovation, Bayer Animal Health GmbH, 51373, Leverkusen, Germany.
| | | | - R J Martin
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
| | - A P Robertson
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
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Shang Kuan TC, Prichard RK. Developmental regulation of Dirofilaria immitis microfilariae and evaluation of ecdysone signaling pathway transcript level using droplet digital PCR. Parasit Vectors 2020; 13:614. [PMID: 33298156 PMCID: PMC7724712 DOI: 10.1186/s13071-020-04480-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/07/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Current measures for the prevention of dirofilariasis, caused by the dog heartworm, Dirofilaria immitis, rely on macrocyclic lactones, but evidence of drug-resistant isolates has called for alternative approaches to disease intervention. As microfilariae are known to be in a state of developmental arrest in their mammalian host and then undergo two molts once inside the arthropod, the aim of this study was to look at the developmental regulation of D. immitis microfilariae that occurs in their arthropod host using in vitro approaches and to investigate the role of the ecdysone signaling system in this development regulation. METHODS Dirofilaria immitis microfilariae extracted from dog blood were incubated under various culture conditions to identify those most suitable for in vitro culture and development of the microfilariae, and to determine the effects of fetal bovine serum (FBS), mosquito cells, and ecdysteroid on the development of the microfilariae. Transcript levels of the ecdysone signaling pathway components were measured with droplet digital PCR (ddPCR). RESULTS In vitro conditions that best promote early development of D. immitis microfilariae to the "late sausage stage" have been identified, although shedding of the cuticle was not observed. FBS had inhibitory effects on the development and motility of the microfilariae, but media conditioned with Anopheles gambiae cells were favorable to microfilarial growth. The transcript level study using ddPCR also showed that ecdysone signaling system components were upregulated in developing microfilariae and that 20-hydroxyecdysone increased the proportion of larvae developing to the sausage and late sausage stages in vitro. CONCLUSIONS The arthropod host environment provides cues required for the rapid development of D. immitis microfilariae, and the ecdysone signaling system may play an important role in filarial nematode developmental transitions. This study contributes to a better understanding of the developmental process of D. immitis microfilariae.
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Affiliation(s)
- Tsai-Chi Shang Kuan
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, Montreal, H9X3V9, Canada.
| | - Roger K Prichard
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, Montreal, H9X3V9, Canada.
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Kotze AC, Gilleard JS, Doyle SR, Prichard RK. Challenges and opportunities for the adoption of molecular diagnostics for anthelmintic resistance. Int J Parasitol Drugs Drug Resist 2020; 14:264-273. [PMID: 33307336 PMCID: PMC7726450 DOI: 10.1016/j.ijpddr.2020.11.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 11/22/2020] [Accepted: 11/26/2020] [Indexed: 02/06/2023]
Abstract
Anthelmintic resistance is a significant threat to livestock production systems worldwide and is emerging as an important issue in companion animal parasite management. It is also an emerging concern for the control of human soil-transmitted helminths and filaria. An important aspect of managing anthelmintic resistance is the ability to utilise diagnostic tests to detect its emergence at an early stage. In host-parasite systems where resistance is already widespread, diagnostics have a potentially important role in determining those drugs that remain the most effective. The development of molecular diagnostics for anthelmintic resistance is one focus of the Consortium for Anthelmintic Resistance and Susceptibility (CARS) group. The present paper reflects discussions of this issue that occurred at the most recent meeting of the group in Wisconsin, USA, in July 2019. We compare molecular resistance diagnostics with in vivo and in vitro phenotypic methods, and highlight the advantages and disadvantages of each. We assess whether our knowledge on the identity of molecular markers for resistance towards the different drug classes is sufficient to provide some expectation that molecular tests for field use may be available in the short-to-medium term. We describe some practical aspects of such tests and how our current capabilities compare to the requirements of an 'ideal' test. Finally, we describe examples of drug class/parasite species interactions that provide the best opportunity for commercial use of molecular tests in the near future. We argue that while such prototype tests may not satisfy the requirements of an 'ideal' test, their potential to provide significant advances over currently-used phenotypic methods warrants their development as field diagnostics.
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Affiliation(s)
- Andrew C. Kotze
- CSIRO Agriculture and Food, St. Lucia, Brisbane, 4072, QLD, Australia,Corresponding author. , CSIRO Agriculture and Food, St. Lucia, Brisbane, 4072, QLD, Australia.
| | - John S. Gilleard
- Department of Comparative Biology and Experimental Medicine, Host-Parasite Interactions Program, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Stephen R. Doyle
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Roger K. Prichard
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, QC, H9X 3V9, Canada
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Selzer PM, Epe C. Antiparasitics in Animal Health: Quo Vadis? Trends Parasitol 2020; 37:77-89. [PMID: 33039282 DOI: 10.1016/j.pt.2020.09.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/09/2020] [Accepted: 09/09/2020] [Indexed: 12/11/2022]
Abstract
Antiparasitics acting on endo- or ectoparasites represent the second largest segment of the global animal health market, accounting for 23% of market share. However, relatively few novel antiparasitic agents have been introduced into the market during recent decades. One exception, and a groundbreaking 21st century success story, are the isoxazolines, whose full potential has not yet been entirely explored. Unfortunately, resistance issues are present across most parasitic diseases, which generates a clear market need for novel resistance-breaking antiparasitics with new modes/mechanisms of action. Recent advances in science and technologies strongly suggest that the time is right to invest in new modalities such as parasitic vaccines or in environmentally friendly interventions.
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Affiliation(s)
- Paul M Selzer
- Boehringer Ingelheim Animal Health, Binger Str. 173, 55216 Ingelheim am Rhein, Germany.
| | - Christian Epe
- Boehringer Ingelheim Animal Health, Binger Str. 173, 55216 Ingelheim am Rhein, Germany
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Shin PT, Baptista RDP, O'Neill CM, Wallis C, Reaves BJ, Wolstenholme AJ. Comparative sequences of the Wolbachia genomes of drug-sensitive and resistant isolates of Dirofilaria immitis. Vet Parasitol 2020; 286:109225. [PMID: 32937243 DOI: 10.1016/j.vetpar.2020.109225] [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: 12/31/2019] [Revised: 08/25/2020] [Accepted: 08/28/2020] [Indexed: 11/25/2022]
Abstract
The recent identification of isolates of D. immitis with confirmed resistance to the macrocyclic lactone preventatives presents an opportunity for comparative genomic studies using these isolates, and examining the genetic diversity within and between them. We studied the genomes of Wolbachia endosymbionts of five isolates of D. immitis maintained at the University of Georgia. Missouri and Georgia-2 are maintained as drug susceptible isolates, and JYD-27, Yazoo-2013 and Metairie-2014 are resistant to the macrocyclic lactone preventatives. We used whole genome amplification followed by Illumina-based sequencing from 8 to 12 individual microfilariae from each of the five isolates, obtaining a depth of coverage of approximately 40-75 fold for each. The Illumina sequences were used to create new genome assemblies for all the Wolbachia isolates studied. Comparisons of the Wolbachia sequences revealed more than 3000 sequence variations in each isolate. We identified 67 loci specific in resistant isolates but not in susceptible isolates, including 18 genes affected.Phylogenetic analysis suggested that the endosymbionts of the drug-susceptible isolates are more closely related to each other than to those from any of the resistant parasites. This level of variation in the Wolbachia endosymbionts of D. immitis isolates suggests a potential for selection for resistance against drugs targeting them.
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Affiliation(s)
- Pei-Tsz Shin
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Rodrigo de Paula Baptista
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA; Institute of Bioinformatics, University of Georgia, Athens, GA, 30602, USA
| | - Connor M O'Neill
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Connor Wallis
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Barbara J Reaves
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Adrian J Wolstenholme
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
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Gerhard AP, Krücken J, Heitlinger E, Janssen IJI, Basiaga M, Kornaś S, Beier C, Nielsen MK, Davis RE, Wang J, von Samson-Himmelstjerna G. The P-glycoprotein repertoire of the equine parasitic nematode Parascaris univalens. Sci Rep 2020; 10:13586. [PMID: 32788636 PMCID: PMC7423980 DOI: 10.1038/s41598-020-70529-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/21/2020] [Indexed: 12/20/2022] Open
Abstract
P-glycoproteins (Pgp) have been proposed as contributors to the widespread macrocyclic lactone (ML) resistance in several nematode species including a major pathogen of foals, Parascaris univalens. Using new and available RNA-seq data, ten different genomic loci encoding Pgps were identified and characterized by transcriptome-guided RT-PCRs and Sanger sequencing. Phylogenetic analysis revealed an ascarid-specific Pgp lineage, Pgp-18, as well as two paralogues of Pgp-11 and Pgp-16. Comparative gene expression analyses in P. univalens and Caenorhabditis elegans show that the intestine is the major site of expression but individual gene expression patterns were not conserved between the two nematodes. In P. univalens, PunPgp-9, PunPgp-11.1 and PunPgp-16.2 consistently exhibited the highest expression level in two independent transcriptome data sets. Using RNA-Seq, no significant upregulation of any Pgp was detected following in vitro incubation of adult P. univalens with ivermectin suggesting that drug-induced upregulation is not the mechanism of Pgp-mediated ML resistance. Expression and functional analyses of PunPgp-2 and PunPgp-9 in Saccharomyces cerevisiae provide evidence for an interaction with ketoconazole and ivermectin, but not thiabendazole. Overall, this study established reliable reference gene models with significantly improved annotation for the P. univalens Pgp repertoire and provides a foundation for a better understanding of Pgp-mediated anthelmintic resistance.
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Affiliation(s)
- Alexander P Gerhard
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Emanuel Heitlinger
- Institute of Biology, Molecular Parasitology, Humboldt-Universität Zu Berlin, Berlin, Germany.,Leibniz Institute for Zoo and Wildlife Research, Research Group Ecology and Evolution of Parasite Host Interactions, Berlin, Germany
| | - I Jana I Janssen
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Marta Basiaga
- Department of Zoology and Animal Welfare, University of Agriculture in Kraków, Kraków, Poland
| | - Sławomir Kornaś
- Department of Zoology and Animal Welfare, University of Agriculture in Kraków, Kraków, Poland
| | - Céline Beier
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Martin K Nielsen
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, USA
| | - Richard E Davis
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, USA
| | - Jianbin Wang
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, USA.,Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
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Shirozu T, Soga A, Fukumoto S. Identification and validation of a commercial cryopreservation medium for the practical preservation of Dirofilaria immitis microfilaria. Parasit Vectors 2020; 13:383. [PMID: 32727546 PMCID: PMC7391585 DOI: 10.1186/s13071-020-04257-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 07/21/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Dirofilaria immitis is a parasitic nematode transmitted by mosquitoes and the cause of heartworm disease in dogs and dirofilariasis in humans and other mammals. The parasite is endemic worldwide. Vector stage research requires a reliable supply of D. immitis microfilariae (mf). It is believed that cryopreserved mf would retain viability and provide a powerful tool for vector stage research. However, reports on cryopreservation of D. immitis mf are limited. Therefore, this study aimed to validate commercial cryopreservation media to establish a practical, convenient and reproducible storage procedure for D. immitis mf. METHODS Six different commercially available cryopreservation media were compared with the traditional polyvinylpyrrolidone-dimethyl sulfoxide (PVP-DMSO) preservation solution. In vitro viability of purified D. immitis mf and mf-infected total blood was analyzed using a motility assay and propidium iodide staining. In vivo infectivity of Aedes aegypti mosquitoes with cryopreserved mf was assessed using a mosquito survival test and quantifying the number of third-stage larvae (L3) after 13 days post-infection. RESULTS Purified mf cryopreserved in CultureSure showed the best viability when compared to mf cryopreserved in the remaining five commercially available media and PVP-DMSO. Viability of mf in mf-infected total blood cryopreserved in CultureSure varied with the ratio of infected blood to CultureSure. Optimum results were obtained with 200 µl mf-infected blood:800 µl CultureSure. CultureSure was also the optimum medium for cryopreserving mf prior to infectivity of A. aegypti. The number of L3 was approximately the same for CultureSure cryopreserved mf (3× concentrated solution) and non-cryopreserved fresh mf. CONCLUSIONS CultureSure is an optimal commercial cryopreservation solution for the storage of D. immitis purified mf, mf-infected total blood, and mf used for in vivo mosquito experiments. Furthermore, this study describes an easy preservation method for clinical D. immitis-infected blood samples facilitating vector stage studies, as well as the study of macrocyclic lactone resistance in heartworms and the education of veterinarians.
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Affiliation(s)
- Takahiro Shirozu
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, 080-8555, Japan
| | - Akira Soga
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, 080-8555, Japan
| | - Shinya Fukumoto
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, 080-8555, Japan.
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Laboratory colonization by Dirofilaria immitis alters the microbiome of female Aedes aegypti mosquitoes. Parasit Vectors 2020; 13:349. [PMID: 32660640 PMCID: PMC7359625 DOI: 10.1186/s13071-020-04218-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 07/06/2020] [Indexed: 11/10/2022] Open
Abstract
Background The ability of blood-feeding arthropods to successfully acquire and transmit pathogens of medical and veterinary importance has been shown to be interfered with, or enhanced by, the arthropod’s native microbiome. Mosquitoes transmit viruses, protozoan and filarial nematodes, the majority of which contribute to the 17% of infectious disease cases worldwide. Dirofilaria immitis, a mosquito-transmitted filarial nematodes of dogs and cats, is vectored by several mosquito species including Aedes aegypti. Methods In this study, we investigated the impact of D. immitis colonization on the microbiome of laboratory reared female Ae. aegypti. Metagenomic analysis of the V3–V4 variable region of the microbial 16S RNA gene was used for identification of the microbial differences down to species level. Results We generated a total of 1068 OTUs representing 16 phyla, 181 genera and 271 bacterial species. Overall, in order of abundance, Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes were the most represented phylum with D. immitis-infected mosquitoes having more of Proteobacteria (71%) than uninfected mosquitoes (56.9%). An interesting finding in this study is the detection of Klebsiella oxytoca in relatively similar abundance in infected and uninfected mosquitoes, suggesting a possible endosymbiotic relationship, and has been previously shown to indirectly compete for nutrients with fungi on domestic housefly eggs and larvae. While D. immitis colonization has no effect on the overall species richness, we identified significant differences in the composition of selected bacterial genera and phyla between the two groups. We also reported distinct compositional and phylogenetic differences in the individual bacterial species when commonly identified bacteria were compared. Conclusions To the best of our knowledge, this is the first study to understand the impact of a filarial infection on the microbiome of its mosquito vector. Further studies are required to identify bacteria species that could play an important role in the mosquito biology. While the microbiome composition of Ae. aegypti mosquito have been previously reported, our study shows that in an effort to establish itself, a filarial nematode modifies and alters the overall microbial diversity within its mosquito host.![]()
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Long T, Alberich M, André F, Menez C, Prichard RK, Lespine A. The development of the dog heartworm is highly sensitive to sterols which activate the orthologue of the nuclear receptor DAF-12. Sci Rep 2020; 10:11207. [PMID: 32641726 PMCID: PMC7343802 DOI: 10.1038/s41598-020-67466-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 05/07/2020] [Indexed: 01/05/2023] Open
Abstract
Prevention therapy against Dirofilaria immitis in companion animals is currently threatened by the emergence of isolates resistant to macrocyclic lactone anthelmintics. Understanding the control over developmental processes in D. immitis is important for elucidating new approaches to heartworm control. The nuclear receptor DAF-12 plays a role in the entry and exit of dauer stage in Caenorhabditis elegans and in the development of free-living infective third-stage larvae (iL3) of some Clade IV and V parasitic nematodes. We identified a DAF-12 ortholog in the clade III nematode D. immitis and found that it exhibited a much higher affinity for dafachronic acids than described with other nematode DAF-12 investigated so far. We also modelled the DimDAF-12 structure and characterized the residues involved with DA binding. Moreover, we showed that cholesterol derivatives impacted the molting process from the iL3 to the fourth-stage larvae. Since D. immitis is unable to synthesize cholesterol and only completes its development upon host infection, we hypothesize that host environment contributes to its further molting inside the host vertebrate. Our discovery contributes to a better understanding of the developmental checkpoints of D. immitis and offers new perspectives for the development of novel therapies against filarial infections.
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Affiliation(s)
- Thavy Long
- INTHERES, Université de Toulouse, INRAE, ENVT, 31027, Toulouse Cedex 3, France.
- Institute of Parasitology, McGill University, Sainte-Anne-De-Bellevue, H9X3V9, QC, Canada.
| | - Mélanie Alberich
- INTHERES, Université de Toulouse, INRAE, ENVT, 31027, Toulouse Cedex 3, France
| | - François André
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Cécile Menez
- INTHERES, Université de Toulouse, INRAE, ENVT, 31027, Toulouse Cedex 3, France
| | - Roger K Prichard
- Institute of Parasitology, McGill University, Sainte-Anne-De-Bellevue, H9X3V9, QC, Canada
| | - Anne Lespine
- INTHERES, Université de Toulouse, INRAE, ENVT, 31027, Toulouse Cedex 3, France.
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Sanchez J, Dharmarajan G, George MM, Pulaski C, Wolstenholme AJ, Gilleard JS, Kaplan RM. Using population genetics to examine relationships of Dirofilaria immitis based on both macrocyclic lactone-resistance status and geography. Vet Parasitol 2020; 283:109125. [PMID: 32535487 DOI: 10.1016/j.vetpar.2020.109125] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 03/24/2020] [Accepted: 04/25/2020] [Indexed: 12/18/2022]
Abstract
Prevention of infection with canine heartworm (Dirofilaria immitis) is based on the compliant administration of macrocyclic lactone (ML) drugs. Resistance to ML drugs is well documented in D. immitis; however, there remains a paucity of information on the spatial distribution and prevalence of resistant isolates. This project aims to improve understanding of ML-resistance by using a population genetic approach. We developed a large panel of microsatellite loci and identified 12 novel highly polymorphic markers. These 12, and five previously published markers were used to screen pools of microfilariae from 16 confirmed drug-susceptible, 25 confirmed drug-resistant, and from 10 suspected drug-resistant field isolates. In isolates where microfilarial suppression testing indicated resistance, Spatial Principal Component Analysis (sPCoA), Neighbor Joining Trees and Bayesian clustering all revealed high genetic similarity between pre- and post-treatment samples. Somewhat surprisingly, the Neighbor Joining tree and sPCoA generated using pairwise Nei's distances did not reveal clustering for resistant isolates, nor did it reveal state-level geographic clustering from samples collected in Georgia, Louisiana or Mississippi. In contrast, Discriminant Analysis of Principle Components was able to discriminate between susceptible, suspected-resistant and resistant samples. However, no resistance-associated markers were detected, and this clustering was driven by the combined effects of multiple alleles across multiple loci. Additionally, we measured unexpectedly large genetic distances between different passages of laboratory strains that originated from the same source infection. This finding strongly suggests that the genetic makeup of laboratory isolates can change substantially with each passage, likely due to genetic bottlenecking. Taken together, these data suggest greater than expected genetic variability in the resistant isolates, and in D. immitis overall. Our results also suggest that microsatellite genotyping lacks the sensitivity to detect a specific genetic signature for resistance. Future investigations using genomic analyses will be required to elucidate the genetic relationships of ML-resistant isolates.
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Affiliation(s)
- Julie Sanchez
- University of Georgia College of Veterinary Medicine, Department of Infectious Diseases, Athens, GA, United States
| | - Guha Dharmarajan
- Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, United States
| | - Melissa M George
- University of Georgia College of Veterinary Medicine, Department of Infectious Diseases, Athens, GA, United States
| | - Cassan Pulaski
- University of Georgia College of Veterinary Medicine, Department of Infectious Diseases, Athens, GA, United States
| | - Adrian J Wolstenholme
- University of Georgia College of Veterinary Medicine, Department of Infectious Diseases, Athens, GA, United States
| | - John S Gilleard
- Faculty of Veterinary Medicine, University of Calgary, Alberta, Canada
| | - Ray M Kaplan
- University of Georgia College of Veterinary Medicine, Department of Infectious Diseases, Athens, GA, United States.
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The efficacy of a topical formulation of selamectin plus sarolaner in preventing the development of a macrocyclic lactone-resistant strain of Dirofilaria immitis in cats. Vet Parasitol 2020; 282:109122. [PMID: 32460111 DOI: 10.1016/j.vetpar.2020.109122] [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: 01/09/2020] [Revised: 04/17/2020] [Accepted: 04/21/2020] [Indexed: 11/22/2022]
Abstract
Revolution®/Stronghold® Plus, a topical endectocide incorporating 6 mg/kg selamectin plus 1 mg/kg sarolaner, is approved for use in cats to prevent heartworm disease. The efficacy of selamectin has not previously been evaluated against any macrocyclic lactone (ML)-resistant heartworm strains in cats for prevention of heartworm disease. In this study, an experimental combination formulation of selamectin (6 mg/kg) plus sarolaner (2 mg/kg) was assessed for preventing the development of a ML-resistant strain of Dirofilaria immitis in cats. Forty purpose-bred domestic shorted-haired cats (20 males; 20 females) from 7-9 months of age and negative for heartworm antigen prior to study inclusion were used. On Day -30, cats were inoculated with 100 D. immitis L3 (ZoeMO strain) subcutaneously in the inguinal area. Cats were randomly allocated to one of the following four treatments with associated dosing regimens: T01 (vehicle-treated control on Days 0, 28, and 56), T02 (single dose of selamectin plus sarolaner combination on Day 0 only), T03 (selamectin plus sarolaner combination on Days 0, 28, and 56) or T04 (single dose of selamectin on Day 0 only). All treatments were administered topically in an isopropyl alcohol-based formulation. Selamectin was administered at 6 mg/kg in both standalone and combination formulations. Sarolaner was administered at 2 mg/kg. Cats were necropsied on Day ∼145 (∼175 days post infection) and adult worms were counted. Nine of ten cats in the control group (T01) were infected with adult worms (range, 1-23; geometric mean, 3.5). In contrast, all cats in T03 had zero heartworms. Only two cats in T02 (0-3; 0.2) and a single cat in the T04 (0-1; 0.1) had heartworms. Compared to T01 (control cats), all treated cats had significantly (p < 0.0001) reduced worm burdens, with treatment efficacies of 100% (T03), 93.5% (T02) and 98% (T04). A topical combination of selamectin (6 mg/kg) plus sarolaner (2 mg/kg) was 100% efficacious in preventing the development of an ML-resistant strain of D. immitis (ZoeMO) in cats when administered as three consecutive monthly treatments. A single dose was highly (93.5%) but incompletely effective.
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