Recently a procine circovirus (PCV) was described that did not cause any il
lness, but a new circovirus has now been detected in many countries that sh
ares less than 80% sequence homology with the first circovirus now named pr
ocine circovirus type 1 (PCV1) and eht new one PCV2. In experimental trials
with colostrum deprived pigs, PVC2 caused in one of four pigs mild clinica
l symptoms, but in combination with procine parvovirus severe wasting disea
se occurred. It is suggested that a number of factors such as too much stre
ss, bad hygienic conditions, large animal concentrations etc. led to the mu
tation.