[Epidemic late abortion in swine--status of research]

This article briefly describes the PRRS (Porcine Reproductive and Respiratory Syndrome), which arose in the winter of 1990 in Germany and other European countries. The data are accumulated from the literature and own experiences. The clinical picture of this new disease, which led to important economical losses is dominated by 1. an increased rate of reduced length of pregnancy with late abortion before day 110 or an increased length of pregnancy; 2. an increase of stillborn piglets; 3. a larger scale of preweaning mortality combined with a higher frequency of secondary infections. Pathological findings in piglets are subcutaneous edema, accumulation of fluids in the body cavities and sometimes interstitial pneumonia is observed. In sows originating from affected farms examined before partus a mononuclear placentitis is present. At present a non-classified virus, isolated by Dutch researchers is proposed to be the causative agent and named Lelystad virus.