Molecular And Epidemiological Investigations Of Key Parasitic Helminths Of Goats In Parts Of Hubei Province

The objective of this thesis was to study aspects of the molecular and epidemiological investigations of key parasitic helminths of goats in Hubei Province,China.The thesis includes a literature review,eight chapters describing the outcomes achieved and a general discussion.The literature review(Chapter 1)revealed some knowledge gaps that needed to be addressed.These gaps were in the areas of epidemiological investigations of goat parasites,molecular identification and diagnosis of goat parasites,and anthelmintic resistance in nematodes of goats.The aims were formulated based on the these knowledge gaps identified in the literature review,namely(i)to survey parasitic helminths of goats in Hubei Province to understand and estimate their prevalence,(ii)to characterise the mitochondrial genomes of important parasites to provide a source of genetic markers for molecular epidemiological,population genetic and phylogenetic studies,(iii)to establish a loopmediated isothermal amplification method for the specific diagnosis of Haemonchus contortus infection and(iv)to undertake surveys of anthelmintic resistance in gastrointestinal nematodes of goats as a basis for future work in this area.The epidemiological investigations of goat helminths in Zhanggang(Chapter 2)and Luotian(Chapter 3)using morphological techniques as well as PCR-based DNA sequencing indicated that the prevalence of helminths was high throughout the year,particularly for gastrointestinal nematodes;Paramphistomum and Haemonchus contortus were prevalent in almost all of the farms investigated.Mitochondrial genomes were characterised for some of the parasites identified,including Fischoederius elongatus(Chapter 4),Gastrothylax crumenifer(Chapter 5)and Homalogaster paloniae(Chapter 6)in order to provide genetic makers for future molecular epidemiological,population genetic and phylogenetic studies.These studies revealed that all three mitochondrial genomes shared the same gene arrangement and indicated that F.elongatus,G.crumenifer and H.paloniae had a relatively close relationship(Chapters 4 to 6).A loop-mediated isothermal amplification(LAMP)method,targeting the second internal transcribed spacer(ITS-2)of H.contortus,was developed to specifically detect H.contortus infection in goats.This method proved to be a sensitive,specific and timesaving approach for specific detection and diagnosis(Chapter 7).During an investigation of goat helminths,over-usage of anthelmintics was common,especially for ivermectin.To investigate anthelmintic resistance,studies were conducted in Zhanggang and Luotian using faecal egg count reduction testing(FECRT)and post mortem examination(Chapters 8 and 9).The results showed the existence of benzimidazole,levamisole and ivermectin resistances in Zhanggang(Chapter 8)and Luotian(Chapter 9).In conclusion,this thesis has contributed to the knowledge of the epidemiology of goat parasites and has molecularly characterised,for the first time,important parasitic trematodes and detected anthelmintic resistance in helminths of goats in Hubei Province(Chapter 10).The findings of this thesis have implications for future studies and for the control of goat parasites in Hubei Province.Although the focus of the thesis was predominantly on parasitic helminths of goats,the outcomes achieved also have implications for studying on the helminths of other livestock animals in China.