The Great Trouble by Deborah Hopkinson

Eel lives in London, in 1854, and he does various odd jobs to survive. He must keep his life a secret, because there's a dangerous man, Fisheye, searching for him. Rumor had it that Eel had died, but somehow Fisheye discovered the truth. Eel seeks help from one of his employers, but the man has fallen ill with cholera, The Blue Death. More people are stricken with the disease, and over seventy citizens have died. Eel seeks help from a doctor he knows, but it may be too late to save other victims, including young children. The doctor's new ideas about the disease may not be enough to stop this deadly plague.

This story is historical fiction, but the author is able to help readers identify with Eel. The plot describes the dangers of cholera, but also introduces scientific advancements regarding the disease. The side problem between Eel and Fisheye adds additional tension to the story.