Table 2.

Number of negative, vaccinated and positive herds and pigs in the study (4852 pigs from 103 herds in GB)

Age of pigs	Negative		Vaccinated		Positive		Total
	Herds	Pigs	Herds	Pigs	Herds	Pigs	Herds	Pigs
8 weeks	35	348	27	264	40	395	102	1007
14 weeks	34	339	27	256	40	396	101	991
Gilts	34	166	27	135	41	204	102	505
Parity 1	33	151	26	129	41	192	100	472
Parity 2	33	157	26	131	41	193	100	481
Parity 3	32	147	25	120	39	192	96	459
Parity 4	32	142	26	123	40	192	98	457
Parity 5+	32	160	26	126	40	194	98	480
Total	35	1610	27	1284	41	1958	103	4852