What should be treated as if known to be infectious?

The correct response is that all human blood and certain bodily fluids should be treated as if known to be infectious. This principle is rooted in universal precautions, which aim to minimize the risk of transmission of bloodborne pathogens, such as HIV, hepatitis B, and hepatitis C. The rationale behind treating all human blood and specific bodily fluids—such as semen, vaginal secretions, and cerebrospinal fluid—as potentially infectious is to enhance safety protocols for healthcare workers and others who might come into contact with these materials. By adopting this mindset, it ensures a consistent and cautious approach to handling these fluids, regardless of the perceived risk level, thus improving overall safety for both personnel and patients.

In contrast, visible blood may not account for unseen potential pathogens in other fluids, while focusing only on critical situations or restricting it to blood and urine samples unnecessarily limits the scope of safety practices. Therefore, treating all human blood and certain bodily fluids as infectious provides a broader and more effective protective measure.