Recrudescence

Recrudescence is the revival of material or behavior that had previously been stabilized, settled, or diminished. In medicine, it is the 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, or 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 Plasmodium parasites, which are responsible for the disease malaria, 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).

The bovine viral diarrhoea virus (bovine virus diarrhea) is said to be recrudescent for some time after clinical signs have abated, because antibodies plateau c. weeks 10–12, and are not lifelong, auto infection may potentially occur in the acutely infected non-pregnant animal. However this is not thought to contribute greatly to the pathogenesis of the disease.

Other diseases that may recur following a short or long period of quiescence include shingles (after chicken pox), oral herpes and genital herpes, and Brill–Zinsser disease (after epidemic typhus).