"Not only is it the title of the poem, but even once we've heard all about Lenore, and the guy in his chamber, it's probably the image of the Raven that sticks most in our minds. It was a pretty great choice on Poe's part, a bird that looks like a part of the black night it came out of, a little scary looking, but also hard to read".
"Our final image of the bird is that of a sleeping demon with burning eyes. He casts a shadow over the whole room, and completely terrifies our poor narrator. Starting out as a sort of funny bird with a strange way of walking into a room, he's now the symbol of pure satanic evil. All that in just 60 lines". -Yahoo
Answer: The author might be suggesting that the bacteria and diseases from the cesspool are leaking into their water source and into the shared water pump water, spreading the disease.
