Table 1.

Results of the laboratory vaccination and challenge trials.

				Morbidity Rate		Mortality Rate
Trial	Group	Sows (n)	Piglets (n)	n	In %	n	In %
1	2 x vaccination	10	20	0 *	0	0 *	0
1	Control	8	16	13	81.25	11	68.75
2	3 x vaccination	9	18	0 *	0	0 *	0
2	Control	10	20	19	95.00	18	90.00

* Significant differences between the vaccinated group and control group (Fisher’s exact test, level of significance p < 0.05 (Fisher’s exact test).