What is the difference between Relapse and Recrudescence?

Question

Specially this term in confusing in case of Malaria.

What actually is the difference and how much is time limit for each?

Answer 1

Relapse - In the life cycle of Plasmodium, some sporozoites go under resting phase instead of proceeding further in the cycle, which later forms hypnozoites giving rise to various symptoms. This called relapse.

Recrudescence - The occurence of clinical symptoms in a malaria patient caused because plasmodium are not eliminated either by immune system or treatment failure is recrudescence.

 

Relapse is not seen in P. falciparum & P. malariae whereas Recrudescence is shown by all species of Plasmodium.

Answer 2

when sporozoites (mainly P Vivax and P Ovale) reach liver cells. They start multiplying to form merozoites, but some of the sporozoites invade liver cells and do not multiply rather go to sleep and called hypnozoite. In future ranging from days, to months, they can start multiplying and can produce merozoites which will lead to an episode of malaria. This is relapse.

Recrudescence, is when the parasite remains in the blood after the episode of malaria. This parasite in the blood, can anytime start multiplication and can cause malaria. This is more common with P falciparum but can happen with all forms of malaria parasites.

Reinfection, is of course a new infection of malaria. It is not possible to differentiate between these terms clinically. And PCR would be needed to confirm this.