Mattie's being bitten by a mosquito is included in the opening chapter of Fever 1793 precisely in order to foreshadow later events, for the deadly fever that descends upon Philadelphia is spread by mosquito bites. At first, the mosquito's insistent buzzing is more irritating than anything else. It's certainly nowhere near as annoying to Mattie as the sound of her mother yelling at her to get out of bed.

But over the course of the book, what started out as just a minor irritation will come to take on great significance in the lives of Mattie and her fellow Philadelphians. Mattie may be sick and tired of hearing her mom's screeching voice, but at some point, she's going to have to help out her family as the fever rapidly spreads and the bodies start piling up in the streets.

As the story begins, she'd like nothing better than to fly away like a mosquito from her boring, humdrum home life. But the sudden outbreak of yellow fever means that Mattie's ambitious plans of a life away from her family have to be put on hold, and for the time being, she's brought crashing down to earth.

Matilda "Mattie" Cook is a young girl living in Philadelphia with her mother and grandfather if 1793. In the first chapter, which takes place on August 16th, Mattie wakes up on a very hot morning with a mosquito buzzing around her ear.

This opening scene provides significant foreshadowing of the events that are about to occur throughout the rest of the book. It is not long before Mattie's mother, Lucille, falls ill, as well as Mattie herself. The sickness they are afflicted with is Yellow fever, a viral disease which results in serious symptoms, including bleeding, kidney issues, fever, chills, muscle pains, and even death. It is spread through the bites of infected mosquitoes.

To provide a bit of context of how serious this epidemic was, consider that in Philadelphia (a city of 50,000 people in 1793), at least 5,000 individuals died. This is one of the worst outbreaks in the history of the United States.