Another management practice implicated in disease spread was failure to house growers and breeders in separate barns. Active trading between farms and movement of pigs over large distances facilitated virus spread during the outbreak. Movement of semen was also implicated in spread of infection between farms. In addition to Perak, Negri Sembilan, and Selangor, other Malaysian states found during the surveillance program to have been infected are Malacca, Penang, and Johore. Additional surveillance and control is planned based on monitoring of pigs at slaughter and trace back of pigs which test positive for infection.
Stringent government controls on the location of pig farms and re-stocking are in place.
One or more neurological signs were also present including trembles and neurological twitches, muscle spasms and myoclonus, rear leg weakness and varying degrees of spastic paresis or lameness, uncoordinated gait when driven and hurried, and generalized pain especially in the hind quarters. Sows and boars also exhibited acute febrile illness with respiratory signs. Other signs included increased salivation and nasal discharge. Sudden death of sows and boars occurred as well as possible first trimester abortion. Neurological signs included agitation and head pressing, tetanus-like spasms, seizures, nystagmus, chomping of the mouth, and apparent pharyngeal muscle paralysis.