Here's the solution:
I made this chart with Dygraphs and hosted it on Github Pages. The embedded version you see here uses the same data and only slightly different CSS from the full mumps chart site, which has a more complete breakdown of affected people in the OSU community.
All data here is taken from the updates Published by Columbus Public Health. They publish numbers for Franklin and Delaware counties in central Ohio every weekday afternoon. I haven't found similar updates for Ohio or the entire United States.
The chart uses a lot of Dygraphs defaults, but I cleaned it up using principles from Dark Horse Analytics' Remove to improve series. Vertical lines are gone, colors have been lightened, the important 'Total' line is thicker, and the numbers have been moved to the right side of the chart, which puts them right by the lines.
Dygraphs has an option for a Google Fusion Tables-style range selector at the bottom of the chart, but at this point that's not necessary. If the mumps outbreak continues for another few months, I'll consider enabling it.
Anyone can use this chart with the following embed code:
<iframe width="100%" height="400px" scrolling="no" frameborder="no" src="https://benlk.github.io/mumps/embed.html"></iframe>
And, because the data is produced by a government agency, anyone can use the data.csv file for their own projects.