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Molecular epidemiology and metabolomic characterisation of Cryptosporidium

Ng, Josephine Su Yin (2017) Molecular epidemiology and metabolomic characterisation of Cryptosporidium. PhD thesis, Murdoch University.

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This thesis examined the molecular epidemiology of the important enteric parasite, Cryptosporidium in Australia with particular reference to cryptosporidiosis in Aboriginal communities, outbreaks, zoonotic transmission and also conducted the first metabolomics analysis of Cryptosporidium.

Chapter 3 revealed striking differences in the epidemiology of Cryptosporidium between Aboriginal and non-Aboriginal people, with notification rates among Aboriginal people up to 50 times higher. Aboriginal people were predominantly infected with C. hominis subtype IdA15G1 and non-Aboriginal people were predominantly infected with C. hominis subtype IbA10G2. Chapters 4 and 5 explored the epidemiology of outbreaks with the C. hominis IbA10G2 subtype, the major subtype identified in all outbreaks.

Chapter 6 examined zoonotic transmission of Cryptosporidium species in rural NSW. Three species of Cryptosporidium were detected in calves; C. parvum, C. bovis and C. ryanae and two in humans; C. parvum and C. bovis. Subtyping identified the concurrence of C. parvum subtypes between calves and humans and this coupled with the identification of the cattle-specific C. bovis in humans and calves provides supportive evidence of zoonotic transmission.

Chapter 7 developed a reproducible faecal extraction method for untargeted gas chromatography-mass spectrometry (GC-MS) analysis and identified distinct differences in faecal metabolite profiles between infected and un-infected individuals. However, as the metabolome is sensitive to external perturbations, a more controlled metabolomics analysis of faecal metabolite profiles was conducted in Chapter 8 using experimentally infected mice. Despite the differences in faecal metabolite profiles between Cryptosporidium infected humans and mice, metabolomic analysis in both studies was still able to clearly differentiate between infected and uninfected hosts, as well as provide information on the metabolic activity of the parasite during the infection based on faecal metabolite profiles.

The finding of this thesis will greatly assist in our understanding of molecular epidemiology of Cryptosporidium in Australia and the biochemistry of this important parasite.

Item Type: Thesis (PhD)
Murdoch Affiliation(s): School of Veterinary and Life Sciences
United Nations SDGs: Goal 3: Good Health and Well-Being
Supervisor(s): Ryan, Una, Trengove, Robert and Maker, Garth
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