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

Abstract

Campylobacter 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.