Section 13D of chapter 265 of the General Laws is hereby amended by striking out the first paragraph and inserting in place thereof the following paragraph:- 

 Whoever commits an assault and battery, including assault and battery by means of a bodily substance, upon any public employee, including but not limited to a public transit worker, when such person is engaged in the performance of their duties at the time of such assault and battery, shall be punished by imprisonment for not less than 90 days nor more than 2½ years in a  house of correction or by a fine of not less than $500 nor more than $5,000. For the purposes of this section, “bodily substance” shall mean any human secretion, discharge or emission including, but not limited to, blood, saliva, mucous, semen, urine or feces.