Veterinary Biosciences - Research Publications

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    Transmission of haemotropic mycoplasma in the absence of arthropod vectors within a closed population of dogs on ectoparasiticides
    Huggins, LG ; Baydoun, Z ; Mab, R ; Khouri, Y ; Schunack, B ; Traub, RJ ; Colella, V (NATURE PORTFOLIO, 2023-06-22)
    Dog-infecting haemotropic mycoplasmas (haemoplasmas), such as Mycoplasma haemocanis and Candidatus Mycoplasma haematoparvum are common blood-borne pathogens of canines that can potentially inflict a substantial burden of disease, particularly in immunosuppressed individuals. Nonetheless, the transmission of these pathogens remains debated as more evidence emerges that they may not be transmitted by vectors, but instead use alternative methods such as aggressive interactions and vertical transmission. Here, we treated forty dogs with two different topically-acting ectoparasiticide products able to prevent vector-borne pathogen infections during an 8-month community trial in Cambodia. A total absence of ectoparasites were observed at all time points, and no new infections caused by pathogens confirmed as being vectorially-transmitted were detected, i.e., Babesia vogeli, Ehrlichia canis, Anaplasma platys, and Hepatozoon canis. Conversely, the number of haemoplasma infections in dogs on both ectoparasiticides rose significantly, with an incidence of 26 infections per 100 dogs at risk per year, providing strong evidence of non-vectorial transmission. Over the study period, dog aggression and fighting were frequently observed, highlighting a different potential mode of transmission. This study presents the first robust evidence that canine haemoplasmas may be transmitted without arthropod vectors drawing attention to the need for new methods to prevent their transmission.
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    Vector-borne and other pathogens of potential relevance disseminated by relocated cats
    Maggi, RG ; Halls, V ; Kramer, F ; Lappin, M ; Pennisi, MG ; Peregrine, AS ; Roura, X ; Schunack, B ; Scorza, V ; Tasker, S ; Baneth, G ; Bourdeau, P ; Bowman, DD ; Breitschwerdt, EB ; Capelli, G ; Cardoso, L ; Dantas-Torres, F ; Dobler, G ; Ferrer, L ; Gradoni, L ; Irwin, P ; Jongejan, F ; Kempf, VAJ ; Kohn, B ; Little, S ; Madder, M ; Maia, C ; Marcondes, M ; Miro, G ; Naucke, T ; Oliva, G ; Otranto, D ; Penzhorn, BL ; Pfeffer, M ; Sainz, A ; Shin, S ; Solano-Gallego, L ; Straubinger, RK ; Traub, R ; Wright, I (BMC, 2022-11-08)
    Large populations of unowned cats constitute an animal welfare, ecological, societal and public health issue worldwide. Their relocation and homing are currently carried out in many parts of the world with the intention of relieving suffering and social problems, while contributing to ethical and humane population control in these cat populations. An understanding of an individual cat's lifestyle and disease status by veterinary team professionals and those working with cat charities can help to prevent severe cat stress and the spread of feline pathogens, especially vector-borne pathogens, which can be overlooked in cats. In this article, we discuss the issue of relocation and homing of unowned cats from a global perspective. We also review zoonotic and non-zoonotic infectious agents of cats and give a list of practical recommendations for veterinary team professionals dealing with homing cats. Finally, we present a consensus statement consolidated at the 15th Symposium of the Companion Vector-Borne Diseases (CVBD) World Forum in 2020, ultimately to help veterinary team professionals understand the problem and the role they have in helping to prevent and manage vector-borne and other pathogens in relocated cats.
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    Assessing the efficacy of albendazole against hookworm in Vietnam using quantitative PCR and sodium nitrate flotation
    Dyer, CEF ; Clarke, NE ; Dinh, NN ; Herath, HMPD ; Hii, SF ; Pickford, R ; Traub, RJ ; Nery, SV ; Fairfax, KC (PUBLIC LIBRARY SCIENCE, 2022-10)
    Preventive chemotherapy (PC), consisting of the regular distribution of anthelmintics to populations or groups of populations at risk, is the primary tool used to control soil-transmitted helminth (STH) infections. This strategy, whilst cost-effective, raises the concern of potential emergence of drug resistance. The efficacy of anthelmintics against STH infections is measured using cure rate (CR) and egg reduction rate (ERR), using microscopy-based techniques such as the Kato-Katz thick smear. However, Kato-Katz has low sensitivity, especially for low-intensity infections, and requires fresh samples that need to be processed quickly. Realtime quantitative PCR (qPCR), which is more sensitive, is emerging as a "gold standard" for STH diagnostics given its higher sensitivity (important in low prevalence settings) and ability to differentiate hookworm species, while sodium nitrate flotation (SNF) may provide a low-cost more sensitive and practical alternative to Kato-Katz in the field. In this study, we examined the efficacy of a locally manufactured brand of albendazole 400 mg ("Alzental") against hookworm in Đắk Lắk province, Vietnam, using both qPCR and SNF. For qPCR, formulae to convert qPCR cycle threshold (Ct) values into eggs per gram of faeces (EPG) were utilised to determine efficacy calculations, and these values directly compared with efficacy values generated using SNF. Factors associated with CR and ERR were examined, and Alzental tablet quality was assessed by comparing with an Australian TGA-approved equivalent "Eskazole" tablet. We observed a CR and ERR of 64.9% and 87.5% respectively using qPCR, and 68.4% and 67.6% respectively using SNF. The tablet composition of Alzental was comparable to Eskazole in terms of active albendazole drug concentration with no evidence of impurities. This study demonstrates that the efficacy of Alzental against hookworm is within the range of previously reported studies for albendazole 400 mg. The study also demonstrates the value of qPCR and SNF as alternatives to standard Kato-Katz methodology for assessment of anthelmintic efficacy.
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    Advanced approaches for the diagnosis and chemoprevention of canine vector-borne pathogens and parasites-Implications for the Asia-Pacific region and beyond.
    Huggins, LG ; Koehler, AV ; Gasser, RB ; Traub, RJ ; Rollinson, D ; Stothard, R (Elsevier, 2023)
    Vector-borne pathogens (VBPs) of canines are a diverse range of infectious agents, including viruses, bacteria, protozoa and multicellular parasites, that are pernicious and potentially lethal to their hosts. Dogs across the globe are afflicted by canine VBPs, but the range of different ectoparasites and the VBPs that they transmit predominate in tropical regions. Countries within the Asia-Pacific have had limited prior research dedicated to exploring the epidemiology of canine VBPs, whilst the few studies that have been conducted show VBP prevalence to be high, with significant impacts on dog health. Moreover, such impacts are not restricted to dogs, as some canine VBPs are zoonotic. We reviewed the status of canine VBPs in the Asia-Pacific, with particular focus on nations in the tropics, whilst also investigating the history of VBP diagnosis and examining recent progress in the field, including advanced molecular methods, such as next-generation sequencing (NGS). These tools are rapidly changing the way parasites are detected and discovered, demonstrating a sensitivity equal to, or exceeding that of, conventional molecular diagnostics. We also provide a background to the armoury of chemopreventive products available for protecting dogs from VBP. Here, field-based research within high VBP pressure environments has underscored the importance of ectoparasiticide mode of action on their overall efficacy. The future of canine VBP diagnosis and prevention at a global level is also explored, highlighting how evolving portable sequencing technologies may permit diagnosis at point-of-care, whilst further research into chemopreventives will be essential if VBP transmission is to be effectively controlled.
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    High-throughput microfluidic real-time PCR for the simultaneous detection of selected vector-borne pathogens in dogs in Bosnia and Herzegovina
    Colella, V ; Huggins, L ; Hodzic, A ; Galon, C ; Traub, R ; Alic, A ; Iatta, R ; Halos, L ; Otranto, D ; Vayssier-Taussat, M ; Moutailler, S (WILEY-HINDAWI, 2022-09)
    A scarcity of information on the occurrence of zoonotic vector-borne pathogens (VBPs), alongside a lack of human and animal health authorities' awareness of pre-existing data, augment the risk of VBP infection for local people and limit our ability to establish control programs. This holds especially true in low-middle income countries such as Bosnia and Herzegovina (BiH). This dearth of information on zoonotic VBPs is bolstered by the inability of previously used diagnostic tests, including conventional molecular diagnostic methods, to detect the full spectrum of relevant pathogens. Considering this, we set out to apply a microfluidic qPCR assay capable of detecting 43 bacterial and protozoan pathogens from blood to accrue critical baseline data for VBPs occurrence in BiH. A total of 408 dogs were tested of which half were infected with at least one VBP of zoonotic or veterinary importance. Leishmania infantum was found in 18% of dogs, reaching a prevalence as high as 38% in urbanized areas of Sarajevo. These data highlight substantially higher levels of L. infantum prevalence when compared to that previously reported using conventional methods using the same samples. Additionally, this high-throughput microfluidic qPCR assay was able to detect pathogens rarely or never reported in canines in BiH, including Anaplasma phagocytophilum (3%), Anaplasma platys (0.2%), haemotropic Mycoplasma (1%) and Hepatozoon canis (26%). Our report of the endemicity of important zoonotic pathogens and those of clinical significance to dogs emphasizes the need for urgent implementation of surveillance and control for VBPs in BiH, targeting both animal and human infections within the country.
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    Nanopore Sequencing Using the Full-Length 16S rRNA Gene for Detection of Blood-Borne Bacteria in Dogs Reveals a Novel Species of Hemotropic Mycoplasma
    Huggins, LG ; Colella, V ; Atapattu, U ; Koehler, A ; Traub, RJ ; Costa, M (AMER SOC MICROBIOLOGY, 2022-12-21)
    Dogs across the globe are afflicted by diverse blood- and vector-borne bacteria (VBB), many of which cause severe disease and can be fatal. Diagnosis of VBB infections can be challenging due to the low concentration of bacteria in the blood, the frequent occurrence of coinfections, and the wide range of known, emerging, and potentially novel VBB species encounterable. Therefore, there is a need for diagnostics that address these challenges by being both sensitive and capable of detecting all VBB simultaneously. We detail the first employment of a nanopore-based sequencing methodology conducted on the Oxford Nanopore Technologies (ONT) MinION device to accurately elucidate the "hemobacteriome" from canine blood through sequencing of the full-length 16S rRNA gene. We detected a diverse range of important canine VBB, including Ehrlichia canis, Anaplasma platys, Mycoplasma haemocanis, Bartonella clarridgeiae, "Candidatus Mycoplasma haematoparvum", a novel species of hemotropic mycoplasma, and Wolbachia endosymbionts of filarial worms, indicative of filariasis. Our nanopore-based protocol was equivalent in sensitivity to both quantitative PCR (qPCR) and Illumina sequencing when benchmarked against these methods, achieving high agreement as defined by the kappa statistics (k > 0.81) for three key VBB. Utilizing the ability of the ONT' MinION device to sequence long read lengths provides an excellent alternative diagnostic method by which the hemobacteriome can be accurately characterized to the species level in a way previously unachievable using short reads. We envision our method to be translatable to multiple contexts, such as the detection of VBB in other vertebrate hosts, including humans, while the small size of the MinION device is highly amenable to field use. IMPORTANCE Blood- and vector-borne bacteria (VBB) can cause severe pathology and even be lethal for dogs in many regions across the globe. Accurate characterization of all the bacterial pathogens infecting a canine host is critical, as coinfections are common and emerging and novel pathogens that may go undetected by traditional diagnostics frequently arise. Deep sequencing using devices from Oxford Nanopore Technologies (ONT) provides a solution, as the long read lengths achievable provide species-level taxonomic identification of pathogens that previous short-read technologies could not accomplish. We developed a protocol using ONT' MinION sequencer to accurately detect and classify a wide spectrum of VBB from canine blood at a sensitivity comparable to that of regularly used diagnostics, such as qPCR. This protocol demonstrates great potential for use in biosurveillance and biosecurity operations for the detection of VBB in a range of vertebrate hosts, while the MinION sequencer's portability allows this method to be used easily in the field.
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    Human social conditions predict the risk of exposure to zoonotic parasites in companion animals in East and Southeast Asia
    Colella, V ; Wongnak, P ; Tsai, Y-L ; Nguyen, V-L ; Tan, DY ; Tong, KBY ; Lu, N ; Fang, F ; Yin, Z ; Wang, J ; Liu, X ; Dong, J ; Nurcahyo, W ; Hadi, UK ; Venturina, V ; Taweethavonsawat, P ; Tiwananthagorn, S ; Le, TQ ; Bui, KL ; Watanabe, M ; Rani, PAMA ; Traub, RJ ; Beugnet, F ; Chalvet-Monfray, K ; Halos, L (SPRINGERNATURE, 2022-11-15)
    BACKGROUND: A recent dramatic surge in pet ownership has been observed across metropolitan areas in Asia. To date, there is a dearth of information on the risk associated with pet ownership for the transmission of parasites on a large scale in Asia, despite this continent giving rise to the largest burden of zoonotic infections worldwide. METHODS: We explored the nature and extent of zoonotic internal (endo-) and external (ecto-) parasites and arthropod-borne pathogens in 2381 client-owned dogs and cats living in metropolitan areas of eight countries in East and Southeast Asia using reliable diagnostic tests and then undertook extensive statistical analyses to define predictors of exposure to zoonotic pathogens. RESULTS: The estimated ORs for overall parasite infections are 1.35 [95% CIs 1.07;1.71] in young animals and 4.10 [1.50;11.2] in the animal group older than 15 years as compared with adult animals, 0.61 [0.48;0.77] in neutered animals as compared to unneutered animals, 0.36 [0.26;0.50] in animals living in urban areas as compared with rural areas, 1.14 [1.08;1.21] for each 1 °C increase of annual mean temperature which varies from 12.0 to 28.0 °C, and 0.86 [0.78;0.95] for each year of life expectancy which varies from 70.9 to 83.3 years. CONCLUSIONS: Here we highlight the influence of human life expectancy and the neutering status of the animals, which reflect increased living standards through access to education and human and veterinary health care, to be both strongly associated with exposure to zoonotic parasites. An integrated approach of local and international authorities to implement and manage educational programs will be crucial for the control of zoonotic infections of companion animals in Asia.
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    Knowledge of Mongolian veterinarians towards canine vector-borne diseases
    Davitt, C ; Traub, R ; Batsukh, B ; Battur, B ; Pfeffer, M ; Wiethoelter, AK (Elsevier BV, 2022-12)
    Mongolia is an expansive nation, dominated by agriculture with livestock under nomadic herder care contributing significantly to the economy. Mongolian veterinarians service these herder's livestock and dogs, and are often the first point of contact for animal health advice, including ectoparasite prophylaxis. Dogs are competent reservoir and sentinel hosts for several zoonotic vector-borne diseases (VBD). These diseases in dogs can be dependent on the presence of other sylvatic or domestic reservoir hosts, the abundance of competent vectors and supporting environmental and climatic conditions. Therefore, VBD present a true One Health challenge. The direct and close association of nomadic herders with livestock and livestock protection dogs coupled with frequent relocation (associated with nomadic lifestyles) places all three host groups (herders, livestock and livestock protection dogs) at risk of acquiring VBD. Our study set out to investigate the overall knowledge, perceptions and practices of Mongolian veterinarians towards canine vector-borne diseases (CVBD). A hardcopy questionnaire was delivered through the Mongolian Veterinary Medical Association to a cohort of veterinarians representing 39% of Mongolia's total veterinary workforce with a 53% response rate. A total of 297 participants were included in the final study. The bulk of participants were livestock veterinarians, followed by mixed animal veterinarians. Overall Mongolian veterinarians' knowledge of CVBD were scored as low (58%; 0–3 points) or medium (32%; 4–6 points) on a ten-point scale. There was a significant discrepancy between self-rated and actual knowledge. Females had 1.7 (95% CI 1.1, 2.8) times higher knowledge compared with males and those veterinarians who had 3–5 canine consultations per day were also found to have higher knowledge (odds ratio 1.4, 95% CI 0.4, 4.5). Most veterinarians utilised two or less resources to source information on CVBD over the previous 12 months. The potential of climate-induced emergence of vector populations and their associated pathogens makes it imperative that veterinarians in Mongolia have the necessary resources and knowledge to be on the forefront of CVBD preparedness and mitigation. This study identifies the knowledge gaps and addresses the need for further resources for Mongolian veterinarians to effectively engage in a One Health approach for negating CVBD in animals and humans.
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    A systematic review and meta-analysis of human and zoonotic dog soil-transmitted helminth infections in Australian Indigenous communities
    Raw, C ; Traub, RJ ; Zendejas-Heredia, PA ; Stevenson, M ; Wiethoelter, A ; Mahanty, S (PUBLIC LIBRARY SCIENCE, 2022-10)
    Soil-transmitted helminths (STH) infect 1.5 billion people and countless animals worldwide. In Australian Indigenous communities, STH infections have largely remained endemic despite control efforts, suggesting reservoirs of infection may exist. Dogs fulfil various important cultural, social and occupational roles in Australian Indigenous communities and are populous in these settings. Dogs may also harbour zoonotic STHs capable of producing morbidity and mortality in dogs and humans. This review provides an overview of human and zoonotic STH infections, identifies the Australian Indigenous locations affected and the parasite species and hosts involved. The meta-analysis provides estimates of individual study and pooled true prevalence of STH infections in Australian Indigenous communities and identifies knowledge gaps for further research on zoonotic or anthroponotic potential. A systematic literature search identified 45 eligible studies documenting the presence of Strongyloides stercoralis, Trichuris trichiura, Ancylostoma caninum, Ancylostoma duodenale, Ancylostoma ceylanicum, undifferentiated hookworm, and Ascaris lumbricoides. Of these studies, 26 were also eligible for inclusion in meta-analysis to establish true prevalence in the light of imperfect diagnostic test sensitivity and specificity by Rogan-Gladen and Bayesian methods. These studies revealed pooled true prevalence estimates of 18.9% (95% CI 15.8-22.1) for human and canine S. stercoralis infections and 77.3% (95% CI 63.7-91.0) for canine A. caninum infections indicating continued endemicity, but considerably more heterogenous pooled estimates for canine A. ceylanicum infections, and A. duodenale, undifferentiated hookworm and T. trichiura in humans. This review suggests that the prevalence of STHs in Australian Indigenous communities has likely been underestimated, principally based on imperfect diagnostic tests. Potential misclassification of hookworm species in humans and dogs due to outdated methodology, also obscures this picture. High-quality contemporary studies are required to establish current true prevalence of parasite species in all relevant hosts to guide future policy development and control decisions under a culturally sound One Health framework.
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    Ancylostoma ceylanicum Hookworms in Dogs, Grenada, West Indies
    Zendejas-Heredia, PA ; Colella, V ; Macpherson, MLA ; Sylvester, W ; Gasser, RB ; Macpherson, CNL ; Traub, RJ (CENTERS DISEASE CONTROL & PREVENTION, 2022-09)
    Ancylostoma ceylanicum hookworms are recognized agents of human infection in the Asia-Pacific region. We investigated prevalence of zoonotic hookworm infections in dogs in Grenada in 2021; 40.8% were infected by hookworms, including Ancylostoma ceylanicum. Surveillance of this parasite in dogs and humans is needed in tropical/subtropical countries in the Americas.