Recrudescence of Plasmodium malariae after Quinine

Plasmodium malariae causes uncommon benign malaria found in the malaria endemic regions mostly of Sub-Saharan Africa. As Plasmodium malariae does not have a continued liver stage in humans the only way to have reinfection without reexposure is through recrudescence. However, reports of its recrudescence after antimalarials are rare with only a handful of case reports in the literature. Research in this field to date has not been able to establish definitively an emergence of resistance in Plasmodium malariae to commonly used antimalarials. In the presented case, patient had a recrudescence of P. malariae after full treatment with quinine and clindamycin. This recrudescence was treated with full course of chloroquine with clearance of parasite from blood immediately after treatment and at two months’ follow up. The recrudescence in this case cannot be explained by mechanisms explained in prior articles. We propose that the indolence of some of the Plasmodium malariae trophozoites in the blood can shield them from the effect of the toxic effects of antimalarials and enable them to produce recrudescence later. However, when recrudescence happens, this should not be considered a case of development of resistance and a course of chloroquine should be considered. 1. Introduction Plasmodium malariae infections are infrequently found in the malaria endemic regions with majority of them reported from Sub-Saharan Africa and Southeast Asia. There they are commonly found as mixed infections with Plasmodium falciparum [1]. Unlike Plasmodium vivax and Plasmodium ovale, Plasmodium malariae is not known to have continued liver cycle with hypnozoites. The only way to have a reinfection without reexposure is from its preexisting erythrocytic forms; this is known as recrudescence. These erythrocytic forms of Plasmodium malariae are known to be the most indolent of all the infective plasmodium species with infections observed decades after exposure. Recrudescence of P. malariae is common if the primary episode of infection goes untreated [1, 2]. However, only a handful of cases have reported recrudescence of Plasmodium malariae even after treatment with different antimalarials [2, 3]. Till date no conclusive evidence is presented in the literature regarding emergence of resistance in Plasmodium malariae that can explain recrudescence in these cases [4–7]. 2. Case The case is of a 65-year-old migrant from Sierra Leone who has been living in the United States for more than a decade. The patient has had history of multiple episodes of malaria infection in childhood but no