1. disease-causing agent non-infectious

2. an animal or insect that is known to transmit a specific disease pathogen

3. white blood cells that eliminate the chances of infection vector

4. non-communicable; cannot be spread through casual contact phagocytes

Insulin is a peptide therapeutic used to manage type 1 diabetes, which affects more than 20 million people worldwide according to the international diabetes federation. a significant limitation to the broad distribution and use of insulin to treat type 1 diabetes is the fact that it must be administered by injection rather than orally. why is insulin administered by injection and not orally?