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Item Wild bovid habitat and infectious disease risk in Thailand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science, School of Veterinary Sciences, Massey University(Massey University, 2024-11-07) Horpiencharoen, WantidaWild bovids are a diverse group of typically large, hoofed ruminant mammals that play crucial functions in ecosystems as seed transporters and prey for predators to maintain biodiversity. However, their conservation status varies from least concern to critically endangered with extinction, depending on the regions and remaining population. The expansion of agricultural areas and livestock farming has led to habitat loss and natural resource sharing, likely increasing the risk of disease transmission and pathogen circulation between humans, wildlife, and domestic animals at the shared habitats or the interface areas. This thesis aims to identify the habitat suitability of five wild bovids remaining in Thailand, understand the consequences of introducing infectious disease into the population, and identify where there is a risk of disease transmission. Therefore, three main studies were conducted: 1) identifying suitable areas for five wild bovid species, including gaur, banteng, wild water buffalo, mainland serow and Chinese goral in Thailand; 2) simulating the impact of infectious diseases of cattle on wild bovid populations, and; 3) mapping potential risk areas between wild bovids and cattle. Initially, I used ecological niche modelling to identify the habitat suitability of five wild bovids remaining in Thailand. Due to poor model predictions for two species (mainland serow and Chinese goral), I excluded these two models from further analyses. The results indicated that over 50% of the potentially suitable areas for the three modelled species (gaur, banteng, wild water buffalo) were located outside protected areas close to human populations and agricultural areas. Then, I simulated the number of animals in a model gaur population with and without infections over 100 years with 100 repetitions using stochastic mathematical models. I selected six bovine infectious diseases with different traits, such as incubation and infectious periods or fatality probabilities, including anthrax, bovine tuberculosis, haemorrhagic septicaemia, lumpy skin disease, foot and mouth disease and brucellosis. I introduced an individual infected animal into a closed population for each infectious disease. The disease-free gaur population grew over time, with infections with different traits having different impacts. The populations infected with chronic diseases (e.g. bovine tuberculosis and bovine brucellosis) showed the greatest decline, while diseases with high mortality but acute disease or high transmission rates with low mortality had less impact on the populations. Finally, I mapped the potential risk areas for disease transmission, assuming that high cattle density and habitat suitability increased transmission risk between wild bovids and livestock. The results also indicated that the potential high-risk areas were at the interface areas at the forest edges where interactions between wildlife and cattle occur. All my studies and findings will require further investigation and validation to gain a deeper and better understanding of the complexity of infectious diseases within wildlife populations and the dynamics of their distributions, but they contribute to supporting wildlife conservation and implementing disease mitigation measures to prevent disease transmission among the populations by highlighting where wild bovids might have suitable habitat, what types of infections may be problems and where mitigation may be better targeted.Item Protothecosis in four dogs in New Zealand.(Taylor and Francis Group, 2023-09-04) Price PSA; Klobukowska HJ; Castillo-Alcala F; Foxwell JA; Orbell GMB; Brown S; Irving ACCASE HISTORIES: Medical records of four dogs diagnosed with protothecosis in New Zealand were reviewed. The dogs were aged between 4 and 9 years and three of the four dogs were female. Breeds were one Labrador, one Miniature Schnauzer and two crossbreeds. The reasons for initial veterinary evaluation were a cough and opaque appearance of the right eye (Case 1), diarrhoea (Cases 2 and 3), and cutaneous disease (Case 4). CLINICAL FINDINGS: The ocular signs were characterised by panuveitis, retinal detachment and secondary glaucoma. Gastrointestinal signs included chronic haemorrhagic diarrhoea due to colitis. Three cases had disseminated infection and developed both bilateral, blinding, ocular disease and chronic gastrointestinal disease. Cutaneous signs consisted of draining fistulae over the olecranon, multifocal cutaneous nodules, and ulceration and tracts of the foot pads. Disseminated protothecosis was confirmed by histopathology of biopsied ocular tissues in Cases 1 and 2 and by gastrointestinal biopsies in Case 3. Prototheca spp. were also identified in cytological specimens from Cases 1 and 4 and recovered by culture in Cases 2 and 4. Cutaneous protothecosis was diagnosed in Case 4 initially by cytology and histopathology of skin lesions, and Prototheca zopfii was confirmed by PCR of cultured organisms. TREATMENT AND OUTCOME: Prior to diagnosis of protothecosis, a variety of treatments were prescribed to treat the gastrointestinal and ocular signs. After diagnosis, only Cases 2 and 4 received medication aimed at treating the protothecal infection, which was itraconazole in both cases. Following the progression of clinical signs and concerns about quality of life, all four dogs were euthanised. DIAGNOSIS: Disseminated protothecosis in three dogs, cutaneous protothecosis in one dog. CLINICAL RELEVANCE: Canine protothecosis is rarely reported, despite the ubiquity of the causal algae, and the disease usually carries an extremely grave prognosis when infection is generalised. In New Zealand, protothecosis should be considered as a differential diagnosis in dogs with panuveitis, chorioretinitis or retinal detachment, colitis, or nodular, ulcerative or fistulating cutaneous lesions.Item The prevalence and production effects of liver fluke (Fasciola hepatica) in New Zealand cattle including evaluation of diagnostic tests : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Palmerston North, New Zealand(Massey University, 2023) Dowling, AndrewThe liver fluke Fasciola hepatica, infects cattle worldwide and is considered a parasite of regional importance in New Zealand although the impact on milk production in that country have not been studied. The test characteristics of two antibody detection ELISAs; IDEXX ELISA (IDEXX Fasciolosis Verification) and an In-House assay using unrefined excretory secretory antigens, plus a coproantigen ELISA (Bio K 201–Monoscreen AgELISA) and faecal egg counts (FEC) were assessed against the gold standard of total fluke counts in naturally infected cattle (cows=29, steers=10). Vat milk of dairy herds on the West Coast of the South Island was assessed for liver fluke infection using the IDEXX ELISA in the autumn, near the end of one lactation (n=430), and spring, near the beginning of the subsequent lactation(n=403). A total of 156 questionnaires determining awareness of liver fluke infection and drenching practices were completed. A cross sectional study of 11 herds (n=1314 cows) in autumn and a longitudinal study of 4 herds (n=485 cows) in spring and autumn used the IDEXX ELISA (measured as SP%) on serum to analyse associations between liver fluke infection and milk production parameters in individual cows. A subset of cows was also faecal sampled for coproantigen and FEC analysis. Notably, a negative linear effect of the loge(total fluke count+1) on liveweight (p=0.02) was found and the coproantigen values showed a significant (p=0.01) quadratic effect for loge(total fluke count+1). The survey showed that infection of herds at a level likely to cause production losses on the West Coast is common, with regional clustering. Milk Fat % decreased 0.0004% points for every 1SP% increase (p=0.004), being 0.05 %points lower for cows with SP%150 than cows with SP%30, and 0.22 %points (p=0.014) lower in cows where SP% increased from ≤30 to ≥150 during lactation compared that those remained ≤30 with an economic cost of $55.19 per infected cow. Of the tests compared, the IDEXX ELISA was superior to the In-House ELISA for sensitivity (Se) and specificity (Sp) but the coproantigen ELISA had the highest Se (96%) and Sp (96%). Overall, liver fluke infection was common in dairy cows but the infection intensity was low, nevertheless a small effect on MF% was determined.Item Discovery of novel plant based compounds to address the drug resistance problem in nematode infested ruminants : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatū, New Zealand(Massey University, 2022) Gupta, ArkaIn this thesis, the discovery of novel compounds from plant extracts towards addressing the drug resistance issue in nematode infested ruminants is presented. The nematocidal efficacy of the plant extracts was tested against the L3 stage nematode larvae through bioassay-guided fractionation and chromatographic separation. Quebracho crude powder (QCP) is the only commercially available source of polyphenols. The efficacy of a separated fraction of the QCP was found to be higher (P<0.05) than the crude extract against batches of L3 larvae. However, the research with QCP encountered many challenges and attention was shifted towards medicinal plants found in New Zealand. From a screening study, the Māori plant Piper excelsum (Kawakawa) was found to be the most effective. Of its different components, the leaf component was found to have the highest nematocidal efficacy. Kawakawa (KK) leaf samples were collected over three seasons and the nematocidal efficacy of the leaf samples was found to be independent. From the bioassay-guided fractionation study, the Water and MeOH solvent fractions were found to be most effective, and they were subjected to further reverse-phase chromatographic separation. It was found that the separated fractions had better anthelmintic efficacy than the parent crude solvent fractions (P<0.05). An improvised separation technique named ‘Hand Controlled Countercurrent Separation’ (HCCCS) based on the principle of CCS was developed. It was found that the fractions obtained from the HCCCS study had better anthelmintic efficacy than the parent MeOH-Fraction-4 and the anthelmintic ivermectin (IVM) (P<0.05). A series of combination formulations were made with the separated fractions and IVM. It was observed that these formulations had better efficacy than IVM and the individual HCCCS Fractions (P<0.05). The HCCCS Fractions were subjected to LC-MS/MS investigation and 34 compounds were identified. Of which, 8 were reported in the literature from published KK research. However, the anthelmintic properties of these compounds were not previously reported. The cytotoxicity evaluation of a series of fractions did not reveal any toxic effect to mammalian epithelial cells. Therefore, there is further potential towards isolating leaf fractions into pure isolates which may possess higher nematocidal efficacy compared to the fractions presented in this thesis.Item Klebsiella pneumoniae in New Zealand sea lions : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū, New Zealand(Massey University, 2018) Pinpimai, KomkiewKlebsiella pneumoniae has been circulating in New Zealand sea lions since the outbreaks during the breeding seasons of 2001/02 and 2002/03 in Sandy Bay, on Enderby Island, Auckland Islands. A large number of pups have since died from K. pneumoniae every year during the breeding season. In order to prevent and control this infection, baseline data including bacterial phenotype and genotype, geographic distribution of the pathogen, and the immune response to the pathogen, have to be established. In this study, hypervirulent (HV) K. pneumoniae was isolated from different sources including New Zealand sea lion (NZSL) pups from different breeding sites, and characterised using a combination of biochemical, phenotypic tests, serological analysis and genotyping via whole genome sequencing. Isolates from pups, substrate samples from different breeding sites, a NZSL adult and birds, all had a close genetic relationship. The isolates have the same basic characteristics including a hypermucoviscous phenotype, serotype 2, and sequence type 86. This suggested clonality of this pathogen. The geographic distribution of the pathogen was found to be Enderby Island, Dundas Island, Campbell Island, and the Otago Peninsula (New Zealand mainland). The isolates analysed were all susceptible to commonly used antibiotics, with the exception of ampicillin. The HV isolates from pups were able to utilise a wide panel of carbon and nitrogen sources and had activity in a wide range of pH from 4.5 to 10, supporting the ability of this pathogen to survive in diverse environments. The findings in this thesis also suggest that the environment can be a reservoir for a short time period. For the long term, between breeding seasons, New Zealand sea lion adults and birds that live around the breeding site are potential reservoirs. The HV isolates from pups were resistant to some innate immune responses, including serum killing ability, oxidative killing ability and phagocytosis by neutrophils and monocytes. Overall, this study provided phenotypic and genotypic information on K. pneumoniae isolated from NZSL pups, as well as some information about innate immune responses to this pathogen, which can aid in the prevention and control of this infection.Item Campylobacter species in dogs and cats and significance to public health in New Zealand : a thesis in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Palmerston North, New Zealand(Massey University, 2016) Bojanić, KrunoslavCampylobacter spp. are a major cause of bacterial gastroenteritis in people in the developed world, including New Zealand. Many sources and transmission routes exist, as these bacteria are common in animals and the environment. C. jejuni is most frequently associated with poultry whereas C. upsaliensis and C. helveticus with dogs and cats, respectively. Published data on Campylobacter in dogs and cats in New Zealand and on the pathogenic potential of C. upsaliensis and C. helveticus are very limited. This thesis investigated the prevalence of Campylobacter spp. in household dogs and cats in Manawatu region, New Zealand, and in raw meat pet food commercially available in Palmerston North, New Zealand. Five Campylobacter spp. were isolated and the prevalence rates were significantly influenced by the culture methods used. C. upsaliensis and C. helveticus were most frequently detected from dogs and cats, respectively and C. jejuni in pet food samples. An expanded panel of culture methods was used to screen working farm dogs and their home-kill raw meat diet in Manawatu. This study reported three Campylobacter spp. and Helicobacter winghamensis as being isolated from dogs for the first time. The culture methods were again shown to bias the prevalence estimates. The isolates of C. upsaliensis and C. helveticus from the household pets study and C. hyointestinalis from locally farmed deer were used in a study to investigate the analytical sensitivity in spiked human clinical faecal samples using the ProSpecTTM Campylobacter Microplate Assay test that was developed for detection of C. jejuni/coli. The results showed the ability of the test to detect all three species and showed the influence of bacterial dose, faecal consistency and of the individual faecal samples on the test results. Further studies investigated the pathogenic potential of C. upsaliensis and C. helveticus in comparison to C. jejuni using an insect model of disease, Galleria mellonella, and whole-genome analyses, respectively. The results of the survival analysis in the G. mellonella study indicated that C. upsaliensis and C. helveticus have pathogenic potential, but to a lesser extent than C. jejuni. Additionally, several variables of experimental design were shown to significantly influence estimates of hazard rates in survival analysis. Whole genome analyses also showed indications of the pathogenic potential of C. upsaliensis and C. helveticus relative to C. jejuni, and how it varies between and within species in association with the core and accessory genomes, functional gene content profiles, and documented and predicted pathogenic proteins. This thesis has furthered our understanding of the epidemiology, detection, and pathogenicity of Campylobacter spp. in dogs, cats and humans, and confirmed raw meat animal food as a potential source of Campylobacter spp. for both people and animals.Item Antimicrobial resistance in young New Zealand horses : a thesis submitted in fulfilment of the requirements for the degree of a Master of Veterinary Science, submitted 12th December 2014, Massey University, Institute of Veterinary, Animal and Biomedical Sciences, New Zealand(Massey University, 2014) Toombs-Ruane, Leah JoThe emergence of bacteria that are resistant to antibiotics used in horses has been reported worldwide, including in Australia, the USA and United Kingdom. There is a lack of published comparative scientific information on the New Zealand equine population. However, recent individual cases of multi-drug resistant (MDR) bacterial infections reported by veterinarians have raised concerns about the situation in New Zealand. The use of antimicrobials coupled with less than ideal prescription practice in the horse industry may have led to inadvertent selection for MDR bacteria. An initial perspective on antimicrobial resistance in NZ is gleaned through a retrospective description of laboratory submissions in the form of a database analysis from 2004 to 2013/2014. In neonates (foals less than three weeks of age), the presence of MDR bacteria was identified in 37.5% (24/64) of foals; although 81.6% (102/125) of bacteria cultured from foals included in the study were sensitive to either penicillin or gentamicin. Of the respiratory samples from horses three-years-old and younger, the most commonly cultured bacteria were Staphylococcus species accounting for 40.1% (310/774) of isolates. These bacteria were sensitive to penicillin, ceftiofur and gentamicin for > 90% of isolates. Of all respiratory equine submissions, MDR bacteria were recovered from 39.2% (93/237) of horses. Using multiple correspondence analysis, MDR was associated with submissions from 2009-2014 and two-year-old horses from the Waikato region. These two population groups were targeted specifically for examination due to the potentially severe consequences of bacterial disease in neonates (Chapter 3), and the anecdotal experience of high clinical use of antimicrobials in young horses, especially in the treatment of clinically apparent respiratory disease (Chapter 4). Multi-drug resistance was assessed as part of this work, and is presented in the systematic literature review (Chapter 2), and in both descriptive studies (Chapters 3 and 4). The results of the two retrospective descriptive studies presented show that there is a substantial proportion of submissions from young horses in New Zealand that grow multi-resistant bacterial isolates, and that there is decreased efficacy of commercially available antimicrobials in this country. The antimicrobial resistance reported in this study has potential clinical implications, and reflects the first step in a multifactorial approach to improve and maintain horse and human health.