I want to know the answer to the following question:
What must an infectious agent only be identified in to satisfy the first of Koch's postulates?
All the background I'm provided with is that "One way of proving that a given disease is "infectious", is to satisfy Koch's postulates (first proposed by Robert Koch), which demands that the infectious agent be identified only in patients and not in healthy controls, and that patients who contract the agent also develop the disease.". Is that enough to answer the question?