Clinical and epidemiological aspects of Plasmodium vivax malaria relapse

One of the peculiarities of malaria caused by P. vivax or P. ovale is the evolutionary cycle of these species, as some sporozoites give rise to evolutionary forms of the parasite, called hypnozoites, which can remain in a latent state in the liver even with adequate treatment. This condition explains the relapse of malaria by these Plasmodium species, which may occur months or years after the treatment of the initial infection (ASHLEY et al, 2018), usually caused by the activation of P. vivax hypnozoites in the period between 28 to 180 days . Relapse, by epidemiological criteria, is defined by the occurrence of a new episode of the disease, being diagnosed with the presence of hematozoa in the peripheral blood without the individual having returned to the endemic area (MARKUS, 2018; PEDRO et al, 2012). The risk of relapse varies by geographic area. Strains of P. vivax in tropical regions cause more rapid and frequent relapses than strains from temperate regions, reaching a relapse rate of 50% within a month after the primary infection. In temperate regions, rates range from 5 to 25% (BAIRD, 2004).

Epidemiology
P. vivax

Jan 2018

Brazil