Five piglet production farms (155-238 sows/farm) were investigated three ti
mes during the suckling period for the occurrence of Isospora suis over the
period of one year. On all five farms I. suis was found to be a common end
oparasite and was associated with diarrhoea. The infection rates were highe
st in litters of 3 or 4 weeks of age (32.6 % and 37.7 %, respectively). I.
suis was also common in the two investigated specialized piglet rearing uni
ts but was not associated with diarrhea in the older piglets. A high standa
rd of hygiene seemingly reduces the risk of isosporosis.