Classical swine fever: virulence and tissue distribution of a 1986 English isolate in pigs

Following the recurrence of classical swine fever in the United Kingdom in 1986, a virus isolated from a single outbreak was studied. A major factor in the spread of this disease is considered to be the presence of infectious virus in tissues taken from animals at certain stages of infection, although their condition may escape detection by routine inspection either before or after slaughter. Intranasal inoculation of the isolate into eight-week-old pigs reproduced the acute form of the disease. The pigs were killed or died between seven and 25 days after inoculation. The virus concentration was determined in a wide range of tissues taken at different stages of infection. Infectious virus was present at high concentrations in all the tissues taken and at all stages of infection. Any porcine tissue is therefore a potential source of infection even when it is taken either before the animal displays detectable signs of disease of after it develops serum neutralising antibodies.