Browsing by Author "Cork, Susan"

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    Characterization of incidental lesions and common causes of morbidity and mortality among free-ranging Leporidae in Canada.
    (2023-09-18) Hunter, Summer T.; Rothenburger, Jamie; Checkley, Sylvia; Weese, J. Scott; Cork, Susan
    Wildlife disease surveillance is an important tool for the discovery and mitigation of disease outbreaks. Research into wildlife disease often focuses on charismatic megafauna, but many small and common species play a vital role in their ecosystem and have regular contact with humans. Leporids are common throughout Canada, are an important prey species, and frequently interact with humans through lawns, gardens, domestic animals, and harvesting activities. However, little is known about their diseases, risks to humans and overall health, particularly in an urban setting. The objectives of this thesis were to investigate major causes of morbidity and mortality as well as common incidental lesions and pathogens amongst leporids in Canada. I conducted a retrospective analysis of 569 cases of deceased leporids submitted to the Canadian Wildlife Health Cooperative between 1990 and 2019. Trauma (215/467; 46.0%), specifically vehicle collisions (51/215; 23.7%), was the most common cause of mortality. Moderate to good body condition, male sex, and no incidental findings were associated with an increased odds of trauma related mortality. Incidental lesions were common amongst all categories of mortality. Zoonotic pathogens observed included Francisella tularensis, Pasteurella spp. and Toxoplasma gondii. I also completed autopsies on 140 presumed road-killed urban leporids collected from within Calgary, Alberta, Canada. There were 29 (20.7%) cases of non-trauma related mortalities, which included one case of Tularemia. The majority of non- trauma related mortalities were classified as open diagnosis (21/140; 15%). Incidental lesions were observed in 37.9% of cases and included nephroblastoma (11/140; 6%), Taenia spp. cysts (20/140; 14%), idiopathic splenomegaly (7/140; 5%), and idiopathic interstitial nephritis (11/140; 8%). Again, moderate to good body condition and a lack of incidental lesions or pathogens were associated with an increased odds of trauma related mortality. Overall, this thesis illustrates that Canadian leporids are competent hosts for a variety of zoonotic pathogens but are themselves vulnerable to human related mortality, particularly if they are in apparent good health. The results from this thesis can be used by the public, human health care professionals, veterinarians, and wildlife biologists to make informed decisions on interacting with and conserving free-ranging leporid populations in Canada.
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    Infectious bronchitis virus (IBV) infection in chickens: Some aspects of pathogenesis and diagnosis
    (2023-12-12) Ishara Muhammadu Isham, Fathima; Abdul Careem, Faizal; Cork, Susan; Gupta, Ashish
    Infectious bronchitis virus (IBV) causes infectious bronchitis (IB) in chickens. IB has a significant impact on the poultry industry. Therefore, this thesis focuses on some aspects of pathogenesis and diagnosis of IBV in chickens. The quantitative polymerase chain reaction (qPCR) technique is used for the detection and quantification of IBV genome load. In this thesis, performance characteristics of the digital PCR (dPCR) technique were compared to qPCR assay for the detection and quantification of IBV genome loads. The dPCR assay had higher assay sensitivity and precision than qPCR assay. Hence, dPCR is a better technique to detect and quantify IBV genome load. In this thesis, we further aimed to evaluate the impact of the presence of maternal antibodies on IBV infection in primary and secondary lymphoid organs. The IBV genome load and histopathological lesion scores were significantly lower in progenies from vaccinated hens compared to progenies from non-vaccinated hens in oropharyngeal and cloacal swabs and in bursa of Fabricius (BF) and cecal tonsils (CT). These findings suggest that the presence of maternal antibody in progeny could provide some degree of protection against IBV infection in BF and CT. In this study we aimed to compare IBV pathogenesis and host immune responses in young male and female chickens. No significant difference was observed between the infected male and female chickens in the IBV shedding, IBV genome load in trachea, lung, kidney, BF, thymus, spleen, and CT and in the IBV-induced lesion in all the tissues. A significantly higher percentage of IBV immune-positive area was observed in the infected male chickens compared to female chickens in kidney. There was no significant difference between infected male and female chickens in all the tissues in the B lymphocytes percentage and in all tissues except trachea in the percentage of cluster of differentiation 8 positive (CD8+) T cells, where female chickens had a higher recruitment when compared to male chickens. Most of the findings of this study suggest that the sex of the chickens does not play a significant role in the pathogenesis of IBV and the host immune response in young chickens.
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    Molecular, Pathogenesis and Immunological Studies of the Canadian Delmarva (DMV/1639) Infectious Bronchitis Virus (IBV) Variant
    (2022-09-16) Hassan, Mohamed Saleh Hussein; Careem, Faizal; Cork, Susan; Coffin, Carla; Goldsmith, Dayna; van der Meer, Franciscus; Buret, Andre; Gallardo, Rodrigo
    Infectious bronchitis virus (IBV) is a gammacoronavirus that infects chickens leading to economic losses globally. Although the disease caused by IBV is known as infectious bronchitis (IB), the virus also replicates and induces lesions in the renal, reproductive, and gastrointestinal systems of chickens. The control of IB relies mainly on using live attenuated and inactivated vaccines. The IBV Delmarva (DMV)/1639 variant has impacted the layer flocks in Eastern Canada over the past few years. The affected flocks showed a high incidence of false layer syndrome (FLS). The studies conducted in this thesis focused on three major areas: 1) molecular characterization of IBV DMV/1639 isolates obtained from clinical cases in Eastern Canada, 2) investigating the pathogenesis of the Canadian IBV DMV/1639 variant and the host responses to this virus in chickens, and 3) evaluating the protective efficacy of the existing IB vaccines against the infection with this virus in chickens. Following whole genome sequencing (WGS), phylogenetic and recombination analyses showed that the Canadian IBV DMV/1639 strain is a chimeric virus derived from a Connecticut (Conn) vaccine-like strain, a 4/91 vaccine-like strain, and one strain that is yet-unidentified. An experimental challenge of 1-day-old specific-pathogen-free (SPF) chicks showed that this virus has a wide tissue tropism and induces marked cystic lesions in the oviduct of growing pullets. A significant drop in egg production, accompanied by characteristic gross and microscopic lesions in the reproductive organs, followed the experimental challenge of SPF chickens at peak of egg production. Infected chickens showed significant recruitments of KUL01+ macrophages and CD4+ and CD8+ T cell subsets in the oviduct tissues. In addition, anti-IBV antibodies were detected systemically and locally in the oviduct washes. Heterologous IB vaccines that are commercially available in Canada protected laying SPF chickens against a drop in egg production induced by the Canadian IBV DMV/1639 strain. Vaccinated chickens had lower viral replication and mild reproductive tract lesions. Overall, the knowledge generated in this thesis contributed to the understanding of IBV-host interactions including virus evolution, pathogenesis, host responses, and vaccination-based control.
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    Pathogenesis of and, host responses to Canadian 4/91 infectious bronchitis virus infection in specific pathogen free chickens
    (2021-07-30) Mohamed Najimudeen, Fathima Shahnas; Abdul Careem, Mohamed Faizal; Cork, Susan; Van Marle, Giudo; van der Meer, Franciscus; Abdul Careem, Mohamed Faizal
    Infectious bronchitis (IB) is an economically important disease in chickens caused by infectious bronchitis virus (IBV), which is a coronavirus. The 4/91 strain of IBV is globally distributed with a broad tissue tropism. In Canada, the 4/91 IBV strain was first recorded in 2011 and was dominant until 2017 in Eastern Canadian poultry flocks. The affected flocks presented clinically with respiratory and egg production problems. Information is lacking on the pathogenesis of Canadian (CAN) 4/91 IBV and host responses to this virus in chickens. Thus, the objectives of the thesis research were to determine the impact of the CAN 4/91 IBV variant on egg production and quality and then, to investigate the nephropathogenicity and host responses mounted against this virus infection in specific pathogen-free (SPF) chickens. To investigate CAN 4/91 IBV infection in laying hens, 28-week-old hens were infected with CAN 4/91 IBV and compared with uninfected controls. The hens were monitored daily for egg production and quality and for other clinical signs. Oropharyngeal (OP) and cloacal (CL) swab samples were collected at predetermined time points. A subset of hens from each group were euthanized at 6 and 10 days post-infection (dpi). We observed that the CAN 4/91 IBV isolate has a very broad tissue tropism including the reproductive tract. However, it did not significantly affect egg production or egg quality with minor histological changes in the shell gland. The analysis of the kidneys showed histopathological lesions in infected animals and significant recruitment of T cells and macrophages. For investigation of pathogenicity of CAN 4/91 IBV in the respiratory tract and kidneys of young chickens, one-week-old, unsexed chickens were infected with CAN 4/91 IBV maintaining uninfected controls. The chickens were monitored daily for clinical signs. At 3, 7 and 10 dpi, 5 chickens from each group were euthanized. IBV replicated and induced histopathological lesions, upregulation of genes of proinflammatory mediators and significant recruitment of T cells and macrophages in lung and kidney tissues. Overall, our study contributed to the understanding of the pathogenesis of and host responses to CAN 4/91 IBV infection in SPF layer chickens.
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    Protocol for 'Tick Surveillance Systems in North America: A Scoping Review'
    (2021-07) Romney, Elise; Cork, Susan; Envik, Akaysha; Ganshorn, Heather; Couloigner, Isabelle; Checkley, Sylvia
    Introduction: Tick surveillance is important to detect new ticks or changes in tick occurrence and distribution within a region. This facilitates communication of and response to changes in tick distribution. Tick surveillance systems also provide a framework from which to assess tick-borne disease carriage. This information can be used to launch further investigation and inform risk assessments and mitigation strategies for tick-borne disease in people and animals. For example, many tick surveillance systems focus on blacklegged ticks, like Ixodes scapularis, that can carry Borrelia burgdorferi, the causative agent of Lyme disease. Lyme disease can cause clinical signs such as erythema migrans, meningitis, cranial neuropathy, arthritis, carditis (1 ) in people and some animal species like dogs and horses. White-footed mice and other small mammals are important natural reservoirs of the bacteria while deer and other mammals can carry the ticks (2,3). Hard ticks (Family: Ixodidae) are found in an increasingly broad range of environments as climate change apparently makes it possible for them to survive in regions where they had not previously been found (4). Lyme disease, and other tick-borne diseases such as Rocky Mountain spotted fever and Anaplasmosis, are a One Health problem, at the interface between human health, animal health, and the environment. Objectives: The primary objective of this scoping review is to describe the characteristics of tick surveillance systems from 1960 onward. This research will focus on reviewing published and grey literature and then describing the characteristics of tick surveillance systems, including location, year, type of surveillance, and method of data collection. Methods: This scoping review will be carried out following PRISMA guidelines for scoping reviews. Databases used include MEDLINE, CAB Abstracts, BIOSIS Previews and the Web of Science Core Collection. ProQuest Dissertations will be searched for relevant dissertations. The articles will be screened at the title and abstract, and full text levels by two reviewers blinded to each other's assessment. Articles published prior to 1960 will be excluded, and only articles that describe surveillance systems will be included. Government websites will also be searched for information about tick surveillance programs, globally.