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| Author(s): |
Patricia de Oliveira Esmerini
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD) |
| Defense date: | 2009-02-19 |
| Examining board members: |
Hilda Fátima de Jesus Pena;
Marcelo Vasconcelos Meireles;
Rodrigo Martins Soares
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| Advisor: | Hilda Fátima de Jesus Pena |
| Abstract | |
Toxoplasmosis is a worldwide zoonosis. Toxoplasma gondii is widely prevalent in humans and other mammals. This protozoan parasite can be transmitted by ingestion of sporulated oocysts. T. gondiioocysts can sporulate in seawater and retain their infectivity for at least six months. Experimentally, bivalve mollusks can filter and retain T. gondii oocysts from the seawater. The aim of this study was to investigate the presence of T. gondii in oysters (Crassostrea rhizophorae) and mussels (Mytella guayanensis) in natural conditions. A total of 300 oysters and 300 mussels were acquired from the Fish Market in Santos city, São Paulo state, from March 2008 to August 2008, and divided in 60 groups of five oysters and 20 groups of 15 mussels. To isolate the parasite, five mice were orally inoculated with tissue homogenates from each group of oysters or mussels. For molecular detection of T. gondii, DNA from mussels was extracted using a standard phenol-chloroform method and DNA from oysters was extracted using the guanidine isothiocianate method. A nested-PCR (Polymerase Chain Reaction) based on the amplification of a 155bp fragment from B1 gene of T. gondii was then performed. Eleven PCR-RFLP (Restriction Fragment Length Polymorphism) markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, CS3 e Apico were used to genotype positive samples. There was no isolation of the parasite by bioassay in mice. T. gondii was not detected in the groups of mussels by n-PCR. There was detection of T. gondii by n-PCR in two groups of oysters (3.3%). Genotyping of these two positive samples was not successful. The results indicate that oysters of the species Crassostrea rhizophorae, the commonest species from the coast of São Paulo, can filter and retain T. gondii oocysts and that the marine environment of the coast of São Paulo state is contaminated with oocysts of this parasite. The ingestion of raw oysters can represent a potential transmission source of T. gondii to humans and marine mammals. (AU) | |