Detection of a morphogenetically novel Sarcocystis hominis-like in the context of a prevalence study in semi-intensively bred cattle in Italy

Abstract

The aim of this study was to determine the prevalence of sarcosporidiosis in semi-intensively bred cattle in northwestern Italy. A diagnostic protocol was setup in which infected animals were identified by rapid histological examination of the esophagus, diaphragm, and heart and the detected Sarcocystis spp. were subsequently typed using conventional electron microscopy in combination with molecular techniques. Sarcosporidia cysts were detected in 78.1% of the animals and were seen most often in the esophagus. The cattle is intermediate host for Sarcocystis hominis (final host, humans and some primates), Sarcocystis cruzi (final host, domestic and wild canids), and Sarcocystis hirsuta (final host, wild and domestic cats).All these three species of Sarcocystis were identified, variously associated, with the following prevalence: S. cruzi (74.2%), S. hirsuta (1.8%), and S. hominis (42.7%). Furthermore, a new S. hominis-like (prevalence 18.5%), characterized by hook-like structures of villar protrusion and a different sequence of the 18S rRNA gene, was identified. The cattle sheds testing positive for zoonotic Sarcocystis were assessed for risk factors contributing to the maintenance of the parasite's life cycle. Significant associations emerged between consumption of raw meat by the farm owner, mountain pasturing, and absence of a sewerage system on the farm and cattle breed. Our study demonstrates that sarcosporidiosis may constitute a public health problem in Italy and indicates several issues to be addressed when planning surveillance and prevention actions. The applied diagnostic approach revealed that cattle can harbor a further type of Sarcocystis, of which life cycle and zoonotic potential should be investigated.

Os parasitas de ovinos

“…Inicialmente, o cão foi identificado como único hospedeiro definitivo de N. caninum (McAllister et al, 1998), posteriormente, os coiotes (Canis latrans) (Gondim et al, 2004), o dingo (Canis lapus dingo) (King et al, 2010), e recentemente os lobos acinzen-tados (Canis lapus) (Dubey et al, 2011) também foram reconhecidos como hospedeiros definitivos, ou seja, que eliminam oocistos nas fezes.…”

“…Os taquizoítos e bradizoítos estão presentes nos hospedeiros intermediários e definitivos, já os oocistos são eliminados somente pelos hospedeiros definitivos (McAllister et al, 1998;Gondim et al, 2004;Dubey et al, 2011). Os taquizoítos apresentam morfologia ovoide, lunar ou globular e medem de 3 μm a 7 μm x 1 μm a 5 μm (Figura 58).…”

“…Para melhorar a especificidade da imunoistoquímica, foi desenvolvido antissoro específico para detecção de taquizoítos e cistos de N. caninum nas amostras teciduais (Cole et al, 1993), mesmo assim, ainda há limitações da técnica (Dubey et al, 2006;Reeit et al, 2007), e a execução e interpretação são difíceis (Hemphill, 1999;Peters et al, 2001).…”

“…Posteriormente à liberação dos esporozoítos, o parasito atravessa a parede do intestino delgado e penetra nas células endoteliais, multiplica-se por merogonia ou esporogonia, evoluindo para merontes primários, iniciando a fase assexuada do ciclo biológico. Após maturação dos merontes primários, merozoítos liberados no fluxo sanguíneo migram para arteríolas, capilares, veias e vênulas, para desenvolvimento das gerações subsequentes, que parasitam capilares sanguíneos de vários órgãos dos hospedeiros, ocorrendo finalmente o desenvolvimento em bradizoítos e formação dos cistos teciduais ou sarcocistos (Figura 61), forma infectante para os hospedeiros definitivos (Fayer, 2004;Domenis et al, 2011). Figura 61 -Cisto de Sarcocystis spp.…”

Current Status of Epidemiology and Diagnosis of Human Sarcocystosis

“…Recent prevalence studies based on morphology and molecular data on S. hominis in cattle revealed that the occurrence of S. hominis infections is rather common, with prevalences of 6.2% to 97.4% (32)(33)(34), 53.5% (35), and 94% (16) in Europe, Asia, and South America, respectively. However, no cases of S. hominis infection were observed in a study performed in North America (36).…”