%relapsing%

a. Marked by a relapse; falling back; tending to return to a former worse state. [ 1913 Webster ]

Relapsing fever (Med.), an acute, epidemic, contagious fever, which prevails also endemically in Ireland, Russia, and some other regions. It is marked by one or two remissions of the fever, by articular and muscular pains, and by the presence, during the paroxism of spiral bacterium (Spirochaete) in the blood. It is not usually fatal. Called also famine fever, and recurring fever. [ 1913 Webster ]