The question is incomplete and the full version can be found online.
Answer:
Following the humoral theory, the suspected cause pointed out by Dr. Hodge was the smell of rotting coffee. This theory made sense to Dr. Rush and Dr. Foulke. However, Dr. Rush remembered the same symptoms from when yellow fever had swept through Philadelphia in 1762, which led him to believe that was the illness the patients were suffering.
Explanation:
In the second chapter of "An American Plague: The True and Terrifying Story of the Yellow Fever Epidemic of 1793", called "All was not right," Jim Murphy describes the process that took Dr. Rush to diagnose that it was yellow fever what was making people ill.