It may be one of the most hotly contested issues of classroom teaching, for all I know: Does the ill professor cancel class, risking the ire of students and the headache of getting the course back on track, or does the ill professor attend, and risk spreading infection among the students?
I'm sure some professors out there would be horrified to learn that I trekked to campus last Thursday, with a definite fever and slight congestion, and held class as usual. In the panic over swine flu, I might be seen as one of those reckless people who doesn't get vaccinated and doesn't enter deep isolation at the first symptom of illness. The decision was based on three things: I was pretty sure I'd caught whatever it was from my students in my first place (2 out of 7 have been out sick in the past few weeks), I could minimize any more contamination by keeping my distance and using hand sanitizer, and we'd missed a class just two weeks before due to a blizzard. Put together, the cost of canceling another class seemed greater than any risk of sharing the fever.
I should consider myself lucky that I have only one class, two days a week, to cause concern; I do not have a full course load, and an illness can't leave me behind in three or four different classes. On the other hand, as an adjunct, I don't have a network of fellow professors I can ask to sub for any of my classes. With any luck, the next time I get sick I will have multiple classes to keep track of - and then I can sit and work through these decisions all over again.