The presence of infected wild boars and hares and the potential for exposure of outdoor pig holdings remain the most important risk factors in the currently affected areas. Semen production is well controlled by legal requirements related to the introduction of boars in semen collection centres, continuous monitoring of disease freedom and semen preparation requirements. However, transmission through this route could constitute an important way of disease dissemination.
http://www.efsa.europa.eu/EFSA/efsa_locale-1178620753812_1211902618690.htm?WT.mc_id=EFSAHL01