Table I.

Number of carrier pigs found positive for Actinobacillus pleuropneumoniae by polymerase chain reaction (PCR), either from tonsillar brushing or from whole tonsils, and by immunomagnetic selective isolation (IMS) at different times during the trial in both the control and treated groups^a

	Time (days)
	−3		30		59
Method	Treated	Control	Treated	Control	Treated	Control
PCR from tonsillar brushing	6	6	1b	6b	1c	4
PCR from whole tonsils	nd	nd	nd	nd	5	6
IMS isolation	nd	nd	nd	nd	5	4

nd — Not done

^aEach group was composed of 6 animals

^bSignificant difference (χ², P < 0.05)

^cOnly 5 animals were tested by PCR from tonsillar brushing at day 59