Diagnosis and isolation of Toxoplasma gondii in horses from Brazilian slaughterhouses

Abstract

This study aimed to investigate anti-Toxoplasma gondii antibodies and to isolate the parasite from the brains of horses processed at slaughterhouses in Brazil. We collected brain and blood samples from 398 horses of various ages, from six Brazilian states. Serum samples were evaluated by indirect fluorescent antibody test (IFAT cut-off titre ≥ 1:64), and brains were submitted to mouse bioassay. Among the 398 horses, positivity for T. gondii was identified in 46 (11.6%) by IFAT and in 14 (3.5%) by mouse bioassay. In 12 of those 14 bioassays, mice were positive only by IFAT (cut-off titre ≥ 1:16), T. gondii being isolated in the remaining two. Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of 18S rDNA to differentiate among T. gondii, Neospora caninum, and Sarcocystis neurona, we found that two of the 14 brains were positive for T. gondii only. For genotyping of the two isolates and the PCR-positive brain, we performed PCR-RFLP based on 13 markers, and SAG2 all samples were Toxoplasma gondii type I. Collectively, IFAT of horse sera and mouse bioassay identified positivity in 60 (15%) of the samples. Our results show that some horses sent to slaughter in Brazil have been exposed to T. gondii.Keywords: Slaughterhouse, horses, Toxoplasma gondii, bioassay, indirect fluorescent antibody test, nested PCR-RFLP. ResumoO objetivo do estudo foi investigar anticorpos anti-Toxoplasma gondii e isolar o parasita do cérebro de equídeos abatidos em matadouros-frigoríficos no Brasil. Colheram-se amostras de 398 cérebros e sangue de equídeos machos e fêmeas de idades variadas, provenientes de seis estados brasileiros. As amostras de soro foram avaliadas pelo teste de imunofluorescência indireta (IFI) para T. gondii (ponto de corte ≥ 64), e os fragmentos de cérebros foram submetidos ao bioensaio em camundongos. Por meio da IFI, 46 (11,6%) equídeos foram soropositivos. Pelo bioensaio em camundongos, 14 (3,5%) cérebros de equídeos testados foram positivos. Em doze dos bioensaios, os camundongos foram positivos somente pela IFI (ponto de corte ≥ 16) e T. gondii foi isolado nos outros dois bioensaios. A PCR-RFLP com base em 18S rDNA para diferenciar entre T. gondii, Neospora caninum, e Sarcocystis neurona foram feitas em todos os 14 cérebros e dois foram positivos apenas para T. gondii. De dois isolados positivos para T. gondii e do cérebro positivo à PCR em que realizou-se a PCR-RFLP, com base em 13 marcadores e SAG2, a genotipagem mostrou ser o T. gondii tipo I para todas as amostras. A IFI de soros de equídeos e do bioensaio em camundongos identificaram positividade em 60 (15%) amostras testadas. Os resultados mostram que alguns cavalos enviados para abate foram expostos ao T. gondii.

Seroprevalence and Genotyping of Toxoplasma gondii in Horses Slaughtered for Human Consumption in Italy

“…Previously reported prevalence values of T. gondii in slaughtered horses were 52.6% by mouse bioassay in Egypt [14], 25% by MAT in China [16], 15% by combination of IFAT and mouse bioassay in Brazil [15], and 6.9% by MAT [13] to 10% by Sabin-Feldman dye test [12] in USA.…”

“…In this study, the observed genotypes within muscle samples show that horses were exposed to infections with a mixed genotype (II/III) in addition to clonal lineages (I and II). In two previous genotyping studies carried out on isolates from equids in Brazil, T. gondii type I and the chicken genotype 163 (TgCkBr220) were reported in horses [15] and a donkey [29], respectively. Type I, II and III strains have different virulence phenotypes in mouse models, with type I strains being the most virulent, and Type II and Type III being avirulent [2].…”

“…Large number of serological surveys have previously demonstrated antibodies to T. gondii in equine serum samples worldwide [11] but few studies focused on slaughtered horses [12][13][14][15][16], and only one has investigated T. gondii genotypes in this host species so far [15]. In European countries, previous reports examined T. gondii seroprevalence in various equine populations [11,17,18] but no data especially related to slaughtered horses are available.…”

Soroprevalência de Toxoplasma gondii em equídeos do Nordeste do Brasil

“…Da mesma forma, no Brasil, estudos sorológicos apontam diferentes prevalências com variação entre 0% e 70% (Ishizuka et al 1975, Silva et al 1981, Larangeira et al 1985, Costa et al 1986, Braccini et al 1992, Barcelos et al 1997, Vidotto et al 1997, Gazêta et al 1997, Garcia et al 1999, Mendonça et al 2001, Naves et al 2005, Villalobos et al 2005, LocatelliDittrich et al 2006, Coiro et al 2012, Oliveira Filho et al 2012, Evers et al 2013, Oliveira et al 2013, Valença et al 2015.…”

Abundance Detection and Molecular Characterization of Toxoplasma gondii by SAG1 Gene in Rodents and Cattle of Golestan Province, Northeast of Iran

“…Because domestic and feral cats are the natural de finitive host, they play an important role in disseminating of toxoplasmosis [1][2][3][4][5]. Rodents are very important reservoir in dissemination of toxoplasmosis in Iran.…”