The bacterium is carried in the tonsils of young weaned pigs, and spread among pigs by nose-to-nose contact or by aerosol over short distances.

• 这种细菌可存在于幼猪的扁桃腺,并通过猪只间鼻子与鼻子的接触或透过近距离的喷沫在猪只中传播。