Relapse of Plasmodium vivax and Plasmodium ovale Malaria with and Without Primaquine Treatment in a Nonendemic Area

Abstract

Background: The effect of primaquine in preventing Plasmodium vivax relapses from dormant stages is well established. For Plasmodium ovale, the relapse characteristics and the use of primaquine is not as well studied. We set to evaluate the relapsing properties of these 2 species, in relation to primaquine use among imported malaria cases in a nonendemic setting. Methods: We performed a nationwide retrospective study of malaria diagnosed in Sweden 1995-2019, by reviewing medical records of 3254 cases. All episodes of P. vivax (n=972) and P. ovale (n=251) were selected for analysis. Results: First time relapses were reported in 80/857 (9.3%) P. vivax and 9/220 (4.1%) P. ovale episodes, respectively (P