Uggh, my pet hate. The 'soldier on' mentality has to go.
I understand that for some you cant dial/wifi it in but for 100% of my office, as long as there is wifi you can work from home in an absolute emergency or yes, if you are sick then stay in bed or the couch and recover.
Ive told managers to tell people to go home because they wanted to be seen as a martyr more than actually performing - while infecting the rest of the office. Ive sent people home myself who said they were really sick and then thought it was OK to sit next to pregnant women.
You dont get an award for showing up sick and you dont get one for dying on the job so just say home.
Edit: We had one guy show up sick and 3-4 days later, we had over 30 people phone in sick. Its still referred to as Typhoid [Surname] around here.