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Tesi etd-02102017-180433

Thesis type
Tesi di dottorato di ricerca
Toxoplasma gondii in livestock animals and their products: Prevalence, infectivity, pathogenesis, histopathology and genotyping
Settore scientifico disciplinare
Corso di studi
tutor Prof.ssa Mancianti, Francesca
Parole chiave
  • experimental infection
  • IHC
  • PCR
  • Toxoplasma gondii
  • genotype
  • livestock animals
  • wild animals
Data inizio appello
Data di rilascio
Riassunto analitico
Toxoplasma gondii is a widespread parasite, able to infect virtually all warm blooded animals, human included. While the infection in most subjects doesn't manifest clinically, in some instances it can induce life-threatening disease. Among the factors influencing the outcome of the disease , genotype of the parasite involved is considered one of the most important. The aim of the study was to evaluate the distribution of T.gondii in livestock animals, with a particular interest on the genotype involved. Since the parasite is widespread within all the homoeothermic animals and is an important threat for animal and human health, the investigation was extended to dogs and wild animals. Horses (153), pigs(375), deer (60), dogs (1811), wild boars(213), wild birds(34) and zoo animals(3) were screened by serology, performing MAT and IFAT assays. Tissues available from seropositive subjects were submitted to DNA extraction to detect parasite DNA by nested PCR. The positive DNA samples were subsequently genotyped using a PCR-RFLP protocol.
Seropositivity rates were variable ranging from 2,1% to 50%. Genotype II was found to be the more represented, although was not the only observed.
Furthermore histological and immunohistochemical studies was performed on naturally infected animals (a fennec, a dog and three lemurs) and mice, which were infected experimentally with two different genotypes of T.gondii (genotype I and II). On murine cases, immunohistochemistry (IHC) was performed in order to evaluate the immune response, revealing T-, B-lymphocytes and macrophages. Genotype I was more virulent, with higher parasite load and more extended area of necrosis compared to genotype II. These finding could be related to a higher presence of B lymphocytes recruited in lungs and liver, the organs most affected by the parasites.
This work tried to be the first epidemiological genotype study of T.gondii in Central Italy, analyzing many animal species; the parasite was also studied focusing on the immune cells recruited by different genotypes ( I vs. II ) in a murine experimental infection