BACKGROUND The target enzyme of pyrimethamine is dihydrofolate reductase (DHFR), but little is known about allelic variants of dhfr in Plasmodium vivax populations. Still less is known about associations between specific alleles and the failure of sulfadoxine/pyrimethamine (S/P) to clear the erythrocytic stages of P. vivax in vivo. METHODS We studied P. vivax dhfr mutations in 24 patients who...

We assessed monthly doses of tafenoquine for preventing Plasmodium vivax and multidrug-resistant P. falciparum malaria. In a randomized, double-blind, placebo-controlled study, 205 Thai soldiers received either a loading dose of tafenoquine 400 mg (base) daily for 3 days, followed by single monthly 400-mg doses (n = 104), or placebo (n = 101), for up to 5 consecutive months. In volunteers compl...

The presence of chloroquine-resistant Plasmodium vivax malaria in the New World has been suspected but not confirmed. We report the cases of three patients who acquired vivax malaria in Guyana, South America, and for whom standard chloroquine therapy (25 mg/kg) failed despite therapeutic blood levels. The optimal treatment of chloroquine-resistant P. vivax malaria is unknown, but recent studies...

Individuals residing in malaria-endemic regions acquire protective immunity after repeated infection with malaria parasites; however, mechanisms of protective immunity and their immune correlates are poorly understood. Blood-stage infection with Plasmodium vivax depends completely on interaction of P. vivax Duffy-binding protein (PvDBP) with the Duffy antigen on host erythrocytes. Here, we perf...

detection of plasmodium vivax specific antibodies with serological tests could be a valuable tool for epidemiological researches. whereas p. vivax cannot be simply obtained in vitro, serological tests using total or semi-purified antigens are infrequently used. given this restriction, the present study investigated whether recombinant p. vivax merozoite surface protein 1 (pvmsp-1 42 kda) could ...

BACKGROUND Plasmodium vivax shows a small prevalence in West and Central Africa due to the high prevalence of Duffy negative people. However, Duffy negative individuals infected with P. vivax have been reported in areas of high prevalence of Duffy positive people who may serve as supply of P. vivax strains able to invade Duffy negative erythrocytes. We investigated the presence of P. vivax in t...

Monoclonal antibodies (MAbs) were produced against the asexual blood stages of Plasmodium vivax and Plasmodium ovale and used to define antigens of plasmodial parasites in an indirect fluorescent antibody assay. The anti-P. vivax MAbs produced two distinct patterns in the indirect fluorescent antibody assay. Four patterns were found with the anti-P. ovale MAbs. Species-specific epitopes were de...

BACKGROUND The erythrocyte polymorphism, Southeast Asian ovalocytosis (SAO) (which results from a 27-base pair deletion in the erythrocyte band 3 gene, SLC4A1Δ27) protects against cerebral malaria caused by Plasmodium falciparum; however, it is unknown whether this polymorphism also protects against P. vivax infection and disease. METHODS AND FINDINGS The association between SAO and P. vivax ...

Malaria and concurrent bacteremia has been described in many reports, most of them with P. falciparum. Concurrent bacteremia with P. vivax infected patients is very rare. We reported 2 cases of salmonella bacteremia with P. vivax infection. Both patients presented with fever and the diagnosis of P. vivax was confirmed microscopically. The first patient presented with fever, jaundice, shock and ...