Epidemiological characterization of Toxoplasma gondii in Lisbon region

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In vitro isolation and seroprevalence of Toxoplasma gondii in stray cats and pigeons in Lisbon, Portugal

Publication . Waap, Helga; Cardoso, R.; Leitão, A.; Nunes, T.; Vilares, Anabela; Gargaté, Maria João; Meireles, José; Cortes, Hélder; Ângelo, Helena

Oral contamination with Toxoplasma gondii oocysts shed by cats into the environment has been linked to severe outbreaks of human toxoplasmosis. Pigeons (Columba livia) are highly susceptible to oral infection with oocysts and indirectly indicate soil contamination, since they feed from the ground. A seroprevalence study was performed on cats and pigeons captured in the city of Lisbon. Serum samples collected from 1507 pigeons captured at 64 feeding sites and 423 stray cats were screened for antibodies anti-T. gondii using a commercial direct agglutination test. Seroprevalence in pigeons was 2.6% (39/1507) (95% CI: 1.9–3.5%) and 37.5% (24/64) of pigeon flocks sampled showed to be infected with T. gondii. The proportion of infected pigeons within seropositive flocks ranged between 4.8% and 21.1%. Among cats, seroprevalence was 44.2% (187/423) (95% CI: 39.5–49.1%). Isolation of T. gondii from animal tissues was attempted by in vitro assay. Inoculation of brain homogenates from 20 pigeons and 56 cats into Vero cell cultures allowed isolation of T. gondii from 13 pigeons (65%) and 15 cats (26.8%). Inoculation of muscle homogenates (heart and limbs) prepared by acid-peptic digestion from a subset of 15 cats resulted in the recovery of T. gondii from 10 cats (66.7%).

2012-07-06Journal article

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Isolation and molecular characterization of Toxoplasma gondii isolated from pigeons and stray cats in Lisbon, Portugal

Publication . Vilares, Anabela; Gargaté, Maria João; Ferreira, Idalina; Martins, Susana; Júlio, Cláudia; Waap, Helga; Ângelo, Helena; Gomes, João Paulo

Cats and pigeons are important factors in the epidemiology of Toxoplasma gondii as felids are the only definitive hosts that can excrete environmentally resistant oocysts, and pigeons share the same places of cats and humans constituting a good model and indicator of the ground field contamination. We aimed to study the virulence and genotypes of T. gondii isolated from pigeons and stray cats in Lisbon, Portugal. Fresh samples of brain from 41 pigeons and 164 cats revealing antibodies to T. gondii were inoculated in mice. Three isolates (one isolated from a cat and two isolated from pigeons) were virulent in the mouse model. Sag2-based genotyping of T. gondii was achieved in 70.7% (29/41) of samples isolated from pigeons (26 samples were type II, two were type III, and one strain was type I). From the cat brain samples, 50% (82/164) yielded Sag2 positive results, where 72 belonged to genotype II and 10 were no type III (it was not possible to discriminate between type I and II). Further genotyping was obtained by multiplex PCR of 5 microsatellites (TUB2, TgM-A, W35, B17, B18), allowing the identification of two recombinant strains that had been previously identified as type II by Sag2 amplification (one isolated from cat brain and the other from pigeon brain). This is the first evidence of recombinant strains circulating in Portugal and the first report of T. gondii genotyping from cats in this country. This study also highlights the importance of environmental contamination in the synanthropic cycle constituting a potential source of human infection.

2014-10-15Journal article

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Genetic and virulence characterization of Toxoplasma gondii strains isolated from pigeons in Lisbon region

Publication . Vilares, Anabela; Gargate, M.J.; Ferreira, I.; Martins, S.; Waap, H.; Ângelo, H.

habitat with cats and humans, bands are observed in recreational areas such as urban parks, playgrounds and parks. The interaction between cats, birds and human population is quite evident favoring the fecal-oral transmission of T. gondii between the definitive host and intermediate hosts, in the urban cycle of the parasite. The results of the inoculation in vivo of the brain homogenates showed pigeon isolation rates (58.5%) significantly higher when compared with previous studies, including the preliminary study in 2006 that the isolation rate in mice was 39,1% (9/23) (Waap 2008) and another that was not achieved any isolation in mouse (Godoi 2010). The genotypic analysis revealed a majority of strains of type II, which is consistent with what has been described in Portugal, the rest of Europe and the USA (Ajzenberg 2005, Fazaeli 2000, Honoré 2000, Howe 1997, Waap 2008) . We also isolated strains of type III and type I. The identification of type III strains in animals have been reported by other authors, but the type I have been rarely found in animals has not been previously described in Portugal except in a preliminary study of our team at the 2008 (Waap 2008). The type I strains are usually associated with high virulence in laboratory mice, leading to death within days. This strain was identified by molecular biology and has not been isolated in vivo. The difficulty in isolation of strain may be related to the small number of cysts of the type I strains can develop, these type strains are considered low cystogenic. Genetic characterization of strains of T. gondii is far from its terminus, more sequences of different genes should be studied to help the understanding of the molecular epidemiology and genetic characterization of T. gondii, a relevant parasite for which these data are lacking. The combination of data from humans and animals, through the use of high resolution genetic characterization should improve our perceptive of T. gondii, which will be ultimately beneficial for the control of T. gondii transmission.

2012-04Conference object

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