I've wondered this too. I can only assume it's because they send infected patients home, and they spread it to their families. That and hospitals & nursing homes, where infected staff may be spreading it between the patients/residents?
man ls > ls.txt
The long-winded way (with groff) is something like: zcat /usr/share/man/man1/ls.1.gz | groff -man -Tascii -P -cbdu > ls.txt