The first-person narration is meant to help readers understand that

Mattie trusts Mr. Carris.

Mattie is unaware of the extent of the problem.

Mr. Carris is responsible for burying the dead.

Mr. Carris reads the newspaper.

Mattie is unaware of the extent of the problem.

Explanation:

I hadn't heard about that. They were burying fever victims every day?

"How many have died, Mr. Carris?" I asked.

The first-person narration is meant to help readers understand that Mattie is unaware of the extent of the problem.