Or if they touch human uncleanness – anything that would make them unclean – even though they are unaware of it, but then they learn of it and realize their guilt (NIV)
Or if he touches human uncleanness, of whatever kind the uncleanness may be with which he becomes defiled, and he is unaware of it, when he does know it, then he shall be guilty. (AMP)
Or if he touch the uncleanness of man, whatsoever uncleanness it be that a man shall be defiled withal, and it be hid from him; when he knoweth of it, then he shall be guilty. (KJV)