Recrudescence
1. Revival of material or behavior that had previously quiesced.

2. A recurrence of symptoms in a patient whose blood stream infection has previously been at such a low level as not to be clinically demonstrable or cause symptoms.

3. The reappearance of a disease after it has been quiescent. For example, a clinical attack after parasites in the blood have dropped markedly and the disease has subsided. The parasites, e.g. Plasmodium

Plasmodium

Plasmodium is a genus of parasitic protists. Infection by these organisms is known as malaria. The genus Plasmodium was described in 1885 by Ettore Marchiafava and Angelo Celli. Currently over 200 species of this genus are recognized and new species continue to be described.Of the over 200 known...

, which are responsible for the disease malaria

Malaria

Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

, can persist in the blood without causing apparent symptoms for a few months. It occurs mainly due to suppression of the immune system. This is an important difference between recrudescence and relapse (which occurs due to reactivation of hypnozoites in the liver).