Abstract
Pigs exposed to relatively small amounts of virus by intradermal inoculation of the feet or by skin sacrification developed clinical disease. Large amounts of virus were recovered from samples taken from the nose, mouth, pharynx, rectum and the prepuce or vagina during the first week of infection and smaller amounts during the second week. Virus was recovered from the faeces of most animals 16 days after infection and from one animal for 23 days. Pigs in contact with inoculated animals were killed at intervals before the appearance of clinical disease. The distribution and amounts of virus in various tissues indicated that infection has most likely gained entry through the skin or the epithelia and mucosae of the digestive tract. Some pigs acquired subclinical infections in which no virus excretion was detected and no transmission of infection to susceptible pigs took place over a period of 5 weeks.