(356) Usually disease is only seen in piglets when the virus first enters the herd. The incubation period is short, only 2 to 3 days, after which sucking pigs become acutely ill, hairy, wander around aimlessly and listlessly and stop sucking their dam. Nervous signs are common. Piglets go into fits and often paddle on their sides. Some piglets may adopt a dog-sitting position and develop vomiting and diarrhoea. During acute disease mortality is very high, approaching 100%. For a period of up to 3 months after the virus enters the herd, sows produce weak pigs at birth and there are high levels of mummification. Vaccination should take place as soon as the disease is diagnosed to boost immunity and mitigate the effects. Clinical signs in the sucking pigs ultimately disappear.