At each test, move negative gilts to the segregated facility. Depopulate gilts positive at 16 weeks of age with the original herd. Retest all gilts in the new herd 30 days after the last addition. Depopulate the original herd, cleaning up as outlined for Plan C, and replace with the newly established herd. This option is recommended for, and is the plan most likely to succeed, in a confinement operation with a high level of infection.
Genetic strains have little value.
There are multiple disease problems. The herd is housed in confinement with a common air source or where separation is difficult to maintain. A significant advantage of this choice is the opportunity to repopulate with healthier, genetically superior swine. Choose warm, dry months, when possible. Sunlight and drying very quickly inactivate the virus.