الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 148 |  |  |
| | | from | 148 | | |
Abstract
ABSTRACT
Toxoplasma gondii is an important zoonotic protozoan parasite that infects all warm-blooded animals including humans and birds. Wild birds are intermediate hosts of the parasite and important prey item of the Felidae family, which are the only animals that act as definitive hosts for the parasite and capable of producing T. gondii oocysts. We investigated T. gondii prevalence in various wild bird species to better understand the parasite’s epidemiology and ecology. We tested 28 wild bird species for T. gondii infection using modified agglutination testing (MAT), polymerase chain reaction (PCR), mice bioassay or a combination of these tests. We detected a T. gondii prevalence of 27.4% (308/1124) in various wild bird species using different methods. We had a prevalence of 78.3% (18/23) in charadriiformes, 48.4% (178/368) in Anseriformes, 20.5% (78/381) in Galliformes, 44.8% in Falconiformes (13/29), 75% in Strigiformes (15/20) and 3.8% in Ciconiiformes (4/106) using MAT. We examined the brains of 197 Columbiformes by molecular methods and only two birds (1%) were T. gondii sequence positive. We successfully isolated viable T. gondii tachyzoites from one red-shouldered hawk (Buteo lineatus) and genotyped it using PCR-RFLP of ten genetic markers (TgHawkFL1, ToxoDB PCR-RFLP genotype #28). We also experimentally infected twenty-five four-week old female domestic turkeys (Meleagris gallapavo) intraperitoneally with T. gondii tachyzoites of two different stains and doses (105 and 108 tachyzoites/ml PBS) to investigate the seroconversion, feed conversion rate (FCR), weight gain pattern and parasite tissue tropism in relation to the parasite dose and virulence. We recorded an increase in FCR and a decrease in bird weight gain and survival rate with increase of T. gondii dose and virulence. The group infected with 108 tachyzoites/ml PBS of the virulent T. gondii strain seroconverted earlier than the other groups and had a significantly higher antibody titers as tested by MAT. Gross and histological findings are also discussed. We documented the presence of T. gondii infection in various wild birds which represents an important host for the maintenance of T. gondii life cycle, and we investigated the progress of the infection in experimentally infected turkeys which support our understanding of the parasite’s life cycle and pathogenesis