In vitro efficacy of antimalarial drugs against Plasmodium vivax on the western border of Thailand

The susceptibility of 20 isolates of Plasmodium vivax on the Thailand-Myanmar border to seven antimalarial drugs was evaluated using the schizont maturation inhibition technique. The geometric mean 50% inhibition concentration (IC(50)) values were quinine = 308 ng/mL, amodiaquine =14 ng/mL, chloroquine =50 ng/mL, mefloquine = 127 ng/mL, sulfadoxine/pyrimethamine (80:1) = 800/10 ng/mL, pyrimethamine = 8 ng/mL, and artesunate = 0.5 ng/mL. Compared with P. falciparum in this area, P. vivax was more sensitive to chloroquine and artesunate, equally sensitive to quinine, and more resistant to mefloquine.     

Diagnosis, Clinical Presentation, and In-Hospital Mortality of Severe Malaria in HIV-Coinfected Children and Adults in Mozambique

Background.?Severe falciparum malaria with human immunodeficiency virus (HIV) coinfection is common in settings with a high prevalence of both diseases, but there is little information on whether HIV affects the clinical presentation and outcome of severe malaria. Methods.?HIV status was assessed prospectively in hospitalized parasitemic adults and children with severe malaria in Beira, Mozambique, as part of a clinical trial comparing parenteral artesunate versus quinine (ISRCTN50258054). Clinical signs, comorbidity, complications, and disease outcome were compared according to HIV status. Results.?HIV-1 seroprevalence was 11% (74/655) in children under 15 years and 72% (49/68) in adults with severe malaria. Children with HIV coinfection presented with more severe acidosis, anemia, and respiratory distress, and higher peripheral blood parasitemia and plasma Plasmodium falciparum histidine-rich protein-2 (PfHRP2). During hospitalization, deterioration in coma score, convulsions, respiratory distress, and pneumonia were more common in HIV-coinfected children, and mortality was 26% (19/74) versus 9% (53/581) in uninfected children (P?相似文献   

Stage-dependent production and release of histidine-rich protein 2 by Plasmodium falciparum

Because of their sequestration in the microcirculation, the pathogenic late stages of Plasmodium falciparum are under-represented in peripheral blood samples from patients with falciparum malaria. Excreted products of the parasite might help to estimate this sequestered biomass. We quantified the stage-dependent production and release per parasite of P. falciparum histidine-rich protein 2 (PfHRP2) with the objective of measuring the sequestered biomass. A simple method to relate parasite stage to parasite age was developed to facilitate this. In four isolates of P. falciparum, the median (range) PfHRP2 content was 2.0fg (0.5-4.3fg) for a young ring stage infected erythrocyte, and 5.4fg (2.1-10.2fg) for the schizont stage. The amount of PfHRP2 in the parasitized erythrocyte increased most during development to the mature trophozoite stage. The median (range) amount of PfHRP2 secreted per parasite per entire erythrocytic cycle was 5.2fg (1.1-13.0fg). A median of 89% of the total PfHRP2 was excreted at the moment of schizont rupture. This assessment of the stage-dependent release of PfHRP2 is an essential prerequisite for future studies aimed at estimating the total patient parasite mass from the peripheral blood PfHRP2 concentration.     

Growth patterns and final height of survivors of childhood leukemia

Growth patterns of 85 survivors of childhood leukemia were analyzed retrospectively. All patients remained in first remission with no central nervous system involvement. The mean age at diagnosis was 5.8 +/- 3.6 years. The diagnoses were acute lymphoblastic leukemia (ALL) in 68 patients (80%) and acute non-lymphoblastic leukemia (ANLL) in 17 patients (20%). All except two patients received cranial irradiation: 51 patients with 1,800 cGy and 32 patients with 2,400 cGy. Mean height SDS was -0.7 +/- 1.36 at the time of diagnosis, which decreased to -0.92 +/- 1.31 by the end of treatment, and further decreased to -1.14 +/- 1.38 at 6 years after cessation of treatment. Mean weight SDS was -0.55 +/- 1.13 at the time of diagnosis, increasing slightly to -0.39 +/- 1.02 at the end of treatment, and decreasing to -0.46 +/- 1.65 at 6 years after cessation of treatment. Of these survivors, 51 patients (26 boys and 25 girls) reached a final height that was 1.04 SDS or 5.3 cm less than their target height. There was no difference of height and weight SDS between patients with ALL and ANLL. Girls and boys had different growth patterns. Girls had a slightly increased height SDS and gained more weight after cessation of treatment, resulting in less final height deficit and overweight for height, whereas boys had further height and weight reduction resulting in more deficit of final height.     

Genetic analysis of the dihydrofolate reductase-thymidylate synthase gene from geographically diverse isolates of Plasmodium malariae

Plasmodium malariae, the parasite responsible for quartan malaria, is transmitted in most areas of malaria endemicity and is associated with significant morbidity. The sequence of the gene coding for the enzyme dihydrofolate reductase-thymidylate synthase (DHFR-TS) was obtained from field isolates of P. malariae and from the closely related simian parasite Plasmodium brasilianum. The two sequences were nearly 100% homologous, adding weight to the notion that they represent genetically distinct lines of the same species. A survey of polymorphisms of the dhfr sequences in 35 isolates of P. malariae collected from five countries in Asia and Africa revealed a low number of nonsynonymous mutations in five codons. In five of the isolates collected from southeast Asia, a nonsynonymous mutation was found at one of the three positions known to be associated with antifolate resistance in other Plasmodium species. Five isolates with the wild-type DHFR could be assayed for drug susceptibility in vitro and were found to be sensitive to pyrimethamine (mean 50% inhibitory concentration, 2.24 ng/ml [95% confidence interval, 0.4 to 3.1]).     

Activities of artesunate and primaquine against asexual- and sexual-stage parasites in falciparum malaria

The activities of primaquine in combination with quinine or artesunate against asexual- and sexual-stage parasites were assessed in 176 adult Thai patients with uncomplicated Plasmodium falciparum malaria. Patients were randomized to one of the six following 7-day oral treatment regimens: (i) quinine alone, (ii) quinine with tetracycline, (iii) quinine with primaquine at 15 mg/day, (iv) quinine with primaquine at 30 mg/day, (v) artesunate alone, or (vi) artesunate with primaquine. Clinical recovery occurred in all patients. There were no significant differences in fever clearance times, rates of P. falciparum reappearance, or recurrent vivax malaria between the six treatment groups. Patients treated with artesunate alone or in combination with primaquine had significantly shorter parasite clearance times (mean +/- standard deviation = 65 +/- 18 versus 79 +/- 21 h) and lower gametocyte carriage rates (40 versus 62.7%) than those treated with quinine (P < or = 0.007). Primaquine did not affect the therapeutic response (P > 0.2). Gametocytemia was detected in 98 patients (56% [22% before treatment and 34% after treatment]). Artesunate reduced the appearance of gametocytemia (relative risk [95% confidence interval] = 0.34 [0.17 to 0.70]), whereas combinations containing primaquine resulted in shorter gametocyte clearance times (medians of 66 versus 271 h for quinine groups and 73 versus 137 h for artesunate groups; P < or = 0.038). These results suggest that artesunate predominantly inhibits gametocyte development whereas primaquine accelerates gametocyte clearance in P. falciparum malaria.     

The role of previously unmeasured organic acids in the pathogenesis of severe malaria

IntroductionSevere falciparum malaria is commonly complicated by metabolic acidosis. Together with lactic acid (LA), other previously unmeasured acids have been implicated in the pathogenesis of falciparum malaria.MethodsIn this prospective study, we characterised organic acids in adults with severe falciparum malaria in India and Bangladesh. Liquid chromatography-mass spectrometry was used to measure organic acids in plasma and urine. Patients were followed until recovery or death.ResultsPatients with severe malaria (n=138), uncomplicated malaria (n=102), sepsis (n=32) and febrile encephalopathy (n=35) were included. Strong ion gap (mean±SD) was elevated in severe malaria (8.2 mEq/L±4.5) and severe sepsis (8.6 mEq/L±7.7) compared with uncomplicated malaria (6.0 mEq/L±5.1) and encephalopathy (6.6 mEq/L±4.7). Compared with uncomplicated malaria, severe malaria was characterised by elevated plasma LA, hydroxyphenyllactic acid (HPLA), α-hydroxybutyric acid and β-hydroxybutyric acid (all P<0.05). In urine, concentrations of methylmalonic, ethylmalonic and α-ketoglutaric acids were also elevated. Multivariate logistic regression showed that plasma HPLA was a strong independent predictor of death (odds ratio [OR] 3.5, 95 % confidence interval [CI] 1.6–7.5, P=0.001), comparable to LA (OR 3.5, 95 % CI 1.5–7.8, P=0.003) (combined area under the receiver operating characteristic curve 0.81).ConclusionsNewly identified acids, in addition to LA, are elevated in patients with severe malaria and are highly predictive of fatal outcome. Further characterisation of their sources and metabolic pathways is now needed.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1023-5) contains supplementary material, which is available to authorized users.     

Platelet-induced autoagglutination of Plasmodium falciparum-infected red blood cells and disease severity in Thailand

The relationship of the platelet-mediated autoagglutination of Plasmodium falciparum-infected red blood cells (IRBCs) to disease severity was investigated in 182 Thai patients with falciparum malaria; it was evident in 43% of uncomplicated malaria (n=63), 41% of severe malaria (n=104), and 100% of cerebral malaria (n=15; P=.001) isolates. The median (range) number of IRBCs in agglutinates per 1000 IRBCs was significantly higher in cerebral malaria (6 [3-42]) than in severe (0 [0-52]) and uncomplicated (0 [0-24]) malaria (P=.01). In multivariate analyses, high parasitemia and cerebral malaria were associated independently with parasite agglutination.