Sixty-one pigs were housed in an isolation unit with three compartments and
five pens. Each compartment had its own ventilation system resulting in ai
r currents flowing from compartment A (pens 1 to 3) towards compartment B (
pen 4), but not towards compartment C (pen 5). Classical swine fever virus
was introduced by the experimental inoculation of one pig in the middle pen
(pen 2) of compartment A. The virus infected the pigs in pen 4, following
the prevalent air currents, and the compartmentalisation had only a retardi
ng effect on the transmission of the virus. The absence of infection in the
pigs in pen 5, which was not different from pen 4 except for the ventilati
on system, indicates that the spread of virus was affected by the air curre
nts.