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The Genus Trichinella is currently thought to consist of 8 seperate species. Several methods have been used to help differentiate these. In this study the ability of three of these species, T. spiralis, T. pseudospiralis, and T. sp. 3 to idependantly infect MRL++ mice was compared at 5, 7, 11, 18 and 20 days post infection ( dpi) with the hope of discovering new distinguishing characteristics. Of interest was the development of inflammation through the accumulation of neutrophils associated with larvae of Trichinella in mouse skeletal muscle. This was evaluated with routine histological stains, endogenous peroxidase staining and immunohistochemical staining specific for neutrophil myeloperoxidase. The inflammatory response in skeletal muscle varied considerably among these three species with neutrophil accumulation being very heavy in the later stages of T. spiralis infection , mild in T. sp. 3 and virtually nonexistant in T. pseudospiralis infections. Also, the appearance of neutrophils was closely correlated with the development of a nurse cell or cyst in the larvae that develop these structures. In T. pseudospiralis where cyst formation is absent, there consistently was a lesser degree of inflammation. These results suggest a possible role of neutrophils involved in inflammation or the process of inflammation itself in the production of nurse cell formation as well as confirming previously described antiinflammatory capabilities of T. sp. 3 and T. pseudospiralis.

No description available.

Despite the popularity of companion animal ownership in Australia, recent and comprehensive information with regard to the prevalence, epidemiology and public health significance associated with gastrointestinal parasites of pet dogs and cats in Australia is largely lacking. The primary aims of this study were to close this knowledge gap and to evaluate the veterinarian’s perception, awareness and knowledge of GI parasites in their locality, from a veterinary and public health stand-point. This included sourcing information with regard to commonly recommended deworming protocols. The awareness of pet owners regarding parasitic zoonoses and the degree of education provided to them by veterinarians was also determined. A total of 1400 canine and 1063 feline faecal samples were collected from veterinary clinics and refuges from across Australia. The overall prevalence of gastrointestinal parasites in dogs and cats was 23.9% (CI 21.7-26.1) and 18.4% (CI 16.1-20.7), respectively. Overall Giardia duodenalis was the most prevalent parasite in dogs (9.3%, CI 7.8-10.8) followed by hookworm (6.7%, CI 5.4-8.0). Isospora felis was the most prevalent parasite in cats (5.6%, CI 4.2-7.0), followed by Toxocara cati (3.2%, CI 2.1-4.3). A highly sensitive and species-specific PCR-RFLP technique was utilized to differentiate the various hookworm species which can infect dogs and cats directly from eggs in faeces. Ancylostoma ceylanicum was detected for the first time in Australia in 10.9% of the dogs found positive for hookworm. This was a significant finding in terms of the zoonotic risk associated with this parasite. The zoonotic potential of Giardia and Cryptosporidium was investigated by genetically characterising isolates recovered from dogs and cats. All but one of the Giardia isolates successfully genotyped were host specific, indicating a low zoonotic risk. It was hypothesized that the lack of zoonotic Giardia Assemblages was a consequence of there being a low prevalence of Giardia in the human population. The Cryptosporidium recovered from dogs and cats was determined to be Cryptosporidium canis and Cryptosporidium felis respectively, a finding which supports growing evidence that Cryptosporidium in companion animals is of limited public health significance to healthy people. Very few of the veterinarians surveyed in the study routinely discussed the zoonotic potential of pet parasites with clients. Most of the veterinarians recommended the regular prophylactic administration of anthelmintics throughout a pet’s life. The low national prevalence of GI parasites reported is most likely a consequence of the widespread use of anthelmintics by pet owners. There is an over-reliance on anthelmintics by veterinarians to prevent and control parasites and their zoonotic risk. This has resulted in veterinarians becoming complacent about educating pet owners about parasites. A combination of routinely screening faecal samples for parasites, strategic anthelmintic regimes and improved pet owner education is recommended for the control of GI parasites in pet dogs and cats in Australia.

Investigations into the phylogeny, genome size, and karyotype of microsporidian Nadeispora canceri were initiated to further characterize the organism. Isolates of N. canceri spores were obtained from both Dungeness (Cancer magisrer) and red rock crabs (Cancer productus). Analysis of the ssu rDNA sequence from spore isolates of the two crab species showed 100% sequence identity among 1,081 nucleotide positions, indicating the same species of microsporidian is infecting both species of crabs. Phylogenetic studies based on the ssu rDNA sequences also showed N. canceri to be most closely related to another crustacean parasite, A meson michaelis. Sequence comparison between the two microsporidian species showed 93% sequence identity (1,001/1081 nucleotide positions). Pulsed field gel electrophoresis was used to estimate the genome size and karyotype of N. canceri isolates obtained from Dungeness and red rock crabs. Resolution of DNA bands on the pulsed field gels revealed both isolates to have a karyotype often chromosome-sized DNA bands. Estimation of the genome size revealed spore isolates from C. magister to have a total genome size of 7.44 Mb and spore isolates from C. productus to have a total genome size of 7.32 Mb. Variations detected in chromosome size culminated in a difference in the genome size between the two isolates. However, the variations in chromosome size were found not to be significant based on the Student's t-test. / Graduation date: 2004

Graduation date: 2001

Reproduction de : Thèse d'exercice : Médecine vétérinaire : Toulouse 3 : 2008. / Titre provenant de l'écran titre. Bibliogr. p. 113-117.

Parasites are an important component of every ecosystem, and their interactions with hosts can directly impact the fitness of the host organisms. Despite their significance, it is still largely unknown which host traits predispose a species to increased risk of parasite attack. In the present study, I investigated host and ecological correlates of parasite load in Lake Tanganyikan cichlids using phylogenetic comparative analyses. Specifically, I tested the effect of body size, brain mass, gut length, depth, trophic level, habitat complexity and mating system on parasite prevalence and diversity.  I found that the variation in both average infracommunity richness and parasite prevalence were partly explained by host body mass and habitat complexity. Total parasite diversity, on the other hand, was significantly related to mating behaviour as well as habitat complexity. The comparative analysis presented here is, to the best of my knowledge, the first to investigate determinants of parasite load in Lake Tanganyikan cichlids. As such, my results support several major hypotheses concerning the factors that underlie parasite prevalence and diversity and have broad implications for our understanding of parasite-host interactions.

No description available.

No description available.