The role of Isospora suis as a pathogen in conventional piglet production in Germany

Abstract

In order to evaluate the prevalence of Isospora suis in conventional piglet production in Germany, pooled faecal samples from 327 pig litters from 18 pig production units (20-320 sows each) were examined. At least 10 litters from each farm were investigated. I. suis was present on 83% of the farms and 42.5% of the litters, the infection rate being highest in the third week of age (48.2%). I. suis was found more frequently in samples of diarrhoea than in firm faeces (49.2% compared to 22.2%). Twenty naturally infected piglets from six of these farms underwent examination post mortem, including histology, virology and bacteriology. Histological examination revealed atrophy of the villi in various degrees, mild crypt hyperplasia, fusion of the villi, metaplastic epithelium, erosions and necrosis, especially in the medium and the posterior jejunum and in the ileum. Asexual and sexual developmental stages of the parasite were found in varying numbers in the epithelium of the whole of the small intestine. Bacteria and viruses were mostly excluded as the cause of diarrhoea, and it was concluded that I. suis was the primary pathogen inducing distinct changes and clinical symptoms of diarrhoea.

Figure 1

. Diarrhoea, dehydration and emaciation during acute isosporosis in a suckling piglet.

Figure 2

. Porcine isosporosis in naturally infected piglets at 8–14 days of age. HE staining. (A) Fibrinous, necrotic enteritis of the caudal jejunum (10 × magnification). (B) Villous atrophy and fusion with epithelial flattening and crypt hyperplasia of the medial jejunum (63 × magnification). (C) Merozoites (Mz) and type I meronts (Mr) in the epithelium of the medial jejunum (250 × magnification). (D) Macrogamonts (Ma) and microgamonts (Mi) in the ileal epithelium (250 × magnification).