Occurrence, clinical involvement and zoonotic potential of endoparasites infecting Swiss pigs

Abstract

In order to estimate the diversity, clinical involvement and zoonotic potential of parasites in pigs submitted for diagnosis to the PathoPig project of the Swiss Federal Food Safety and Veterinary Office, faeces (n=125) from suckling piglets (n=39), weaners (n=60) and piglets beginning fattening (n=26) from 74 Swiss farms were examined by 3 coproscopical methods (i.e. sedimentation/zinc chloride-flotation; SAFC and Ziehl-Neelsen staining). Samples microscopically positive for Cryptosporidium were further tested by PCR/sequencing for species assessment. The most frequently detected parasite was Balantidium coli, a facultative pathogenic ciliate with zoonotic potential, in 5.1, 36.7 and 50.0% of suckling, weaners and fatteners and 43.2% of farms; however, no association with disease was observed. Isospora (syn. Cystoisospora) suis infections were detected in 13.3 and 11.1% of suckling piglets with and without diarrhoea, and in 10.0 and 13.3% of weaners and fatteners with diarrhoea, respectively, and were significant associated with emaciation. Cryptosporidium infections were detected in 10.3, 15.0 and 19.2% of sucklings, weaners and fatteners, respectively, and in 18.9% of the farms. Interestingly, two age-related species were identified: C. suis in younger piglets (2 to 6weeks) and C. scrofarum in older ones (6 to 17weeks). None of the pigs infected with C. scrofarum (n=8), but 3 of 4 piglets infected with C. suis (co-infection with I. suis in 2 cases) had diarrhoea. The zoonotic species C. parvum was not detected, nevertheless, sporadic cases of human infection with the porcine-adapted species have been reported. Ascaris suum, Trichuris suis and Strongylida were rarely detected (<4%) in all age categories.

Clinical cystoisosporosis associated to porcine cytomegalovirus (PCMV, Suid herpesvirus 2 ) infection in fattening pigs

“…Therefore, when diagnosing cystoisosporosis in a herd, false negative results could be obtained if only individual animals with diarrhoea are sampled. Consequently, the analysis of pooled faecal samples from several animals is recommended [2,6]. Accordingly, in this study, C. suis oocysts were detected in the faeces from further 17-18 week-old fattening pigs with diarrhoea of the group.…”

“…While in many experimental infections the peak of oocyst shedding occurred before the peak of diarrhoea [20][21][22], in some experiment using high oocysts doses, diarrhoea was observed during the prepatent period, before oocyst shedding started [23]. Also the high amount of water in diarrhoeic faeces could produce a dilution of putatively shed oocysts, thus lowering the diagnostic sensitivity of coproscopy [2]. Therefore, when diagnosing cystoisosporosis in a herd, false negative results could be obtained if only individual animals with diarrhoea are sampled.…”

“…Faecal samples collected at necropsy were also tested for Rotavirus A and porcine Coronaviruses (Transmissible Gastroenteritis Virus [TGEV] and Porcine Epidemic Diarrhoea [PED]) antigens by immunochromatography using commercial kits (FASTest® ROTA Strip Megacor, Hörbranz, Austria and Anigen Rapid TGE/PED Ag Test kit BioNote, Gyeonggi-do, Korea, respectively). Additionally, a bacteriological investigation mainly directed to detect enterotoxigenic Escherichia coli (ETEC) was performed as described by Schubnell et al [2]. Ileum sections were examined histopathologically for Lawsonia intracellularis infection using the Warthin-Starry silver nitrate-based stain, and tonsils, mediastinal and mesenterial lymph nodes sections were analysed by immunohistochemistry for Porcine Circovirus Type 2 (PCV-2) infection using the monoclonal antibody F217 [17].…”

“…Isospora) suis is the causative agent of cystoisosporosis or neonatal porcine coccidiosis. This protozoan parasite is regarded as one of the main causes of diarrhoea in suckling piglets worldwide and it is also widely distributed in Switzerland [1,2]. It is associated with big economic losses due to high morbidity, slower growth rates, reduced post-weaning performance and high costs of prophylaxis and treatment [3][4][5].…”

Chestnut extract but not sodium salicylate decrease the severity of diarrhea and enterotoxigenic Escherichia coli F4 shedding in artificially infected piglets

“…Enterotoxigenic Escherichia coli (ETEC) is a prevalent pathogen involved in PWD [2]. For instance, in Switzerland, 42.5% of weaned pigs with diarrhea were identified as having ETEC [3]. Those bacteria possess fimbriae that adhere to receptors located on the apical side of the enterocytes and secrete enterotoxins, including heat labile toxin (LT) and heat stable toxin (STb), which results in fluid secretion into the intestinal lumen, leading to dehydration and acidosis, which ultimately results in diarrhea [4, 5].…”