Mattilsynet, Norway's food and veterinary watchdog, says the number of pig herds in Nord Trondelag county infected by H1N1 as of Oct. 15 has increased to eight.
Three of six new samples tested were found to be positive for the virus. Mattilsynet is concerned about the illness passing from humans to pigs.
Mattilsynet added it will expand the use of restrictions concerning infected pigs or pigs suspected of being infected; the most important of which is the non-movement of live animals. The transport of pigs for slaughter will be allowed following necessary approvals.
The group noted it would try to find whether pig herds in other parts of Norway are infected, focusing on areas with the highest concentration of pig farms.