Infectious Disease Compendium

Faget Sign

Diagnosis

Aka pulse-temperature disassociation (it is French, so pronounced fah-jay. Warning: using a hard g will result in suffering the approbation of others).

Liebermeister's rule: When the temperature goes up a degree, the pulse should go up 10 (except, of course, when the patient has heart block from their myocardial abscess or is on beta-blockers). So when the febrile patients does not get appropriately tachycardic, they have Faget sign.

It has an interesting differential that is always fun for Chief of Service rounds: typhoid fever, brucellosis, psittacosis, legionellosis, tularemia, yellow fever (for which it was first observed), dengue are the big ones. Also Colorado tick fever, Mycoplasma pneumonia.

Last Update: 07/10/18.