Table 1.

Relationship between ages of pigs and frequency of PEV-9 by RT-PCR

Age of pigs	Number of samples analysed	Number of positive samples (%)
<10 weeks	120	11 (9.2)
10-15 weeks	119	12 (10.1)
16-20 weeks	105	9 (8.6)
>20 weeks	103	5 (4.9)
Total	447	37 (8.3)