He seemed <i>fine</i> yesterday

He seemed fine yesterday

Yellow fever is a particularly nasty way to die (the accompanying 'black vomit' is partially-digested blood that collects in the victim's stomach, and is said to resemble coffee grounds), and in the 19th century, people were terrified of it, moreso than many other, more lethal diseases. A virulent outbreak in 1878 caused more than 20,000 deaths in Memphis, TN, and over half the residents fled for their lives. Contemporary reports of the disease are chilling, especially considering that doctors of the time could only guess at its causes. It would take until 1900, when Walter Reed, working from the papers of Carlos Finlay, finally attributed its spread to mosquitoes.

It may not seem so, but the Doctor is being merciful -- "treatments" for yellow fever often included enemas, mustard applied to the feet, and hot bricks placed on the arms and legs.