Virus is excreted in the stools for two weeks preceding the onset of symptoms . The incidence in first world countries is declining. There is an especially high incidence in developing countries and rural areas. Transmission - Enteric Large numbers of virus particles are excreted in stools, before the onset of symptoms. Outbreaks in creches are very common.
Viraemia is transient.
A large inoculum of virus is needed to establish infection. Epidemiology Little is known yet. The incidence of infection appears to be low in first world countries. This suggests that a large inoculum is needed to establish infection. The incidence of infection in South Africa is unknown.