How is pneumonia personified in the story?

"The Last Leaf," by O. Henry, is a bittersweet tale of compassion and sacrifice. The major events of the novel begin when one of the main characters, a woman named Johnsy, is stricken with pneumonia. Rather than simply saying that the woman has contracted the sickness, Henry writes of the illness as if it were a person. Often with personification, something is given human attributes but never actually called by human terms. In this short story, O. Henry writes, "[t]oward winter a cold stranger entered Greenwich Village. No one could see him." This is who Henry will dub "Mr. Pneumonia" in the next paragraph. The illness is treated so much like a person that it is even assigned gender. Henry continues the personification by saying that Mr. Pneumonia "walked around touching one person here and another there with his icy fingers." It is said that "[o]n the east side of the city he hurried, touching many people; but in the narrow streets of Greenwich Village he did not move so quickly." In discussing the shifting rate with which the illness spreads, Henry makes it seem even more like a crotchety old man, saying shortly thereafter that "Mr. Pneumonia was not a nice old gentleman."O. Henry's use of personification makes pneumonia seem not only more formidable but also more personal.