down with a disease
down with (an illness)
Sick with a particular illness, which is named after "with." I've been down with the flu all week and have barely gotten out of bed.
See also: down
*down with a disease
ill; sick at home. (Can be said about many diseases. *Typically: be ~; Come ~; get~.) Tom isn't here. He's down with a cold. Sally is down with the flu.