PRRSV is one of several known viruses to cross the placenta that includes parvovirus and Nipah. Infected fetuses suffer from vasculitis， especially of the umbilicus which could be the cause of their death. Fetal death is not uncommon in swine， but it is not a cause of abortion. However， infection of the sow can cause abortion “storms” even if the litter is not affected， possibly through some neuro-endocrine mechanism. Since PRRSV is highly contagious， an infected sow can readily infect her healthy newborn litter causing a respiratory disease that increases the risk of secondary infection . Altogether these pathologies explain the origin of the name PRRS.
