Final answer:
Hand hygiene, specifically regular and thorough hand washing with soap and water, is the number one defense against transmission of blood-borne pathogens.
Step-by-step explanation:
The number one defense against transmission of blood-borne pathogens is hand hygiene. Regular and thorough hand washing with soap and water is the most effective way to prevent the spread of many pathogens, including those transmitted through direct skin contact or the fecal-oral route. Hand hygiene is also crucial in reducing the spread of respiratory illnesses such as flu and the common cold. It is recommended to wash hands for at least 20 seconds, making sure to scrub all surfaces of the hands, including between the fingers and under the nails.