Recrudescence is the recurrence of an undesirable condition. In

medicine Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

, it is usually defined as the recurrence of

symptom Signs and symptoms are diagnostic indications of an illness, injury, or condition. Signs are objective and externally observable; symptoms are a person's reported subjective experiences. A sign for example may be a higher or lower temperature ...

s after a period of remission or quiescence, in which sense it can sometimes be synonymous with

relapse In internal medicine, relapse or recidivism is a recurrence of a past (typically medical) condition. For example, multiple sclerosis and malaria often exhibit peaks of activity and sometimes very long periods of dormancy, followed by relapse or r ...

. In a narrower sense, it can also be such a recurrence with higher severity than before the remission. "Relapse" conventionally has a specific (albeit somewhat illogical) meaning when used in relation to malaria (see below).

Malaria

malaria Malaria is a Mosquito-borne disease, mosquito-borne infectious disease that affects vertebrates and ''Anopheles'' mosquitoes. Human malaria causes Signs and symptoms, symptoms that typically include fever, Fatigue (medical), fatigue, vomitin ...

, recurrence can take place due to ''recrudescence''; or ''relapse''; or ''re-infection'' (via mosquito transmission). ''Relapse'' means that a recurrence has been precipitated by a dormant stage in the liver called a "hypnozoite". Thus, ''relapse'' is applied only for those plasmodial species that have hypnozoites in the life cycle, such as ''

Plasmodium vivax ''Plasmodium vivax'' is a protozoal parasite and a human pathogen. This parasite is the most frequent and widely distributed cause of recurring malaria. Although it is less virulent than ''Plasmodium falciparum'', the deadliest of the five huma ...

'' and '' P. ovale''. On the other hand, ''recrudescence'' means that circulating, multiplying parasites are detected after having persisted in the bloodstream (or elsewhere) at undetectable levels for a period of time, as merozoites (as opposed to hypnozoites). This term is applied for ''Plasmodium'' species that are not associated with hypnozoite-mediated recurrences, such as '' P. falciparum'', '' P. malariae'', and '' P. knowlesi''. ''Recrudescence'' is also used for malarial recurrence caused by drug-resistant strains of ''P. vivax'' and ''P. ovale'' where parasites remained in the bloodstream despite treatment.

Melioidosis

In melioidosis, a recurrent infection can be due to ''re-infection'' and ''relapse''. ''Re-infection'' is a recurrence of symptoms due to an infection with a new strain of '' Burkholderia pseudomallei'' following the eradication therapy of melioidosis. Meanwhile, ''relapse'' are those who presented with melioidosis symptoms due to failure to clear the infection in the bloodstream after completion of eradication therapy. On the other hand, ''recrudescence'' is the recurrence of melioidosis symptoms during the eradication therapy.

Bovine viral diarrhoea

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.

Others

Other diseases that may recur following a short or long period of quiescence include

shingles Shingles, also known as herpes zoster or zona, is a viral disease characterized by a painful skin rash with blisters in a localized area. Typically the rash occurs in a single, wide mark either on the left or right side of the body or face. T ...

(after chicken pox), oral herpes and

genital herpes Genital herpes is a herpes infection of the genitals caused by the herpes simplex virus (HSV). Most people either have no or mild symptoms and thus do not know they are infected. When symptoms do occur, they typically include small blisters ...

, and Brill–Zinsser disease (after epidemic typhus).

References

{{Wiktionary Parasitology