Seven germ-free piglets (Groot Yorkshire 9 [Cofok 9 Large White]) were obtained by caesarean section and housed in isolators, fed with sterilized condensed milk till the age of 14 days and thereafter with pelleted feed (sterilized by X-ray radiation) and water ad lib. On day 21, three of the seven piglets were transported to the necropsy room and served as uninfected control piglets.