RESUMO
PURPOSE: Toxoplasma gondii is a zoonotic parasite capable of infecting a wide range of hosts. Free-range chickens are important sentinels in the epidemiology of this parasite as they feed from the ground and are likely to ingest oocysts shed in the faeces of infected cats. Atypical strains of T. gondii are known to dominate in South America where they are associated with more severe disease in humans, yet relatively little is known about the strains circulating in neighbouring Caribbean islands. METHODS: In this study, hearts and brains were collected from free-range chickens in Antigua and Barbuda (n = 45), Dominica (n = 76) and Trinidad (n = 41), and DNA was extracted for nested ITS1 PCR and PCR-RFLP. Sera were collected and screened for antibodies using the modified agglutination test (MAT). RESULTS: Antibodies to T. gondii were detected in 20.5, 38.2 and 17.1% of chickens in Antigua and Barbuda, Dominica and Trinidad, respectively. Toxoplasma gondii DNA was also detected by PCR in 24.4, 17.1 and 17.1% of chickens, respectively, giving an overall prevalence of 31.1, 42.1, and 29.3% for each of the 3 island nations. Results of PCR-RFLP revealed 2 new atypical genotypes (designated ToxoDB #281 and #282) and one Type III (ToxoDB #2) in chickens from Antigua. Partial genotyping of a further 8 isolates (7 from Antigua and one from Trinidad) revealed different allele-types at five or more markers for 7 of the isolates, suggesting atypical genotypes. CONCLUSIONS: This is the first study to report the prevalence of T. gondii in free-range chickens in Antigua and Barbuda, Dominica and Trinidad and Tobago. It is also the first to report the presence of atypical genotypes in Antigua and Barbuda and Trinidad and Tobago.
Assuntos
Galinhas/parasitologia , Variação Genética , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/parasitologia , Toxoplasma/genética , Toxoplasmose Animal/epidemiologia , Animais , Anticorpos Antiprotozoários/sangue , Encéfalo/parasitologia , DNA de Protozoário/genética , Genótipo , Coração/parasitologia , Prevalência , Índias Ocidentais/epidemiologiaRESUMO
A detailed ontogenetic immunocytochemical study is reported on gut-associated lymphoid development in the Brazilian marsupial Didelphis albiventris. This employed antibody probes raised to evolutionarily conserved peptides which have been shown to detect HLA-DR-like (class II MHC) antigens and T and B cell markers in a wide range of animal species. Cells with macrophage and dendritic morphology expressing class II MHC and a few cells expressing the T cell marker CD3 were found in the lamina propria of duodenal villi in early (approximately 24 mm crown-rump length) latent opossum. Cells with B cell markers were not detected until lactent animals reached > 60 mm. Development of Peyer's patches (PP) was seen first in the duodenum in 45-60 mm lactent animals, progressing to well developed PP in the duodenum and ileum in lactent animals > 80 mm. These PP, like those in weanling and juvenile animals, consisted of follicles with a network of class II MHC positive dendritic cells and round cells lacking T and B markers, but lacking well defined mantle zones. B cells were present mainly in the lymphatic sinuses, with CD3 T cells present between follicles in the PP and intraepithelially in the villi. The study reveals the sequential development of class II MHC positive dendritic cells, T cells and B cells in the intestinal ontogeny of the opossum PP. These features occurred initially exclusively in the duodenum and subsequently in the ileum, paralleling the physiological maturation of the gut in eutheria.