Statisical Abstracts is the authoritative and comprehensive summary of statistics on the social, political, and economic conditions of the United States. Tables can be downloaded in Excel and Chapters as PDF documents. Keywords such as infection can be used to locate relevant tables.
The US government collects statistics on a variety of topics that can be useful for public health students. Here are some places to start.
County Level
CDC SNAPS – Snap Shots of State Population Data