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1.  Magnetic resonance imaging of the brain in adults with severe falciparum malaria 
Malaria Journal  2014;13:177.
Magnetic resonance imaging (MRI) allows detailed study of structural and functional changes in the brain in patients with cerebral malaria.
In a prospective observational study in adult Bangladeshi patients with severe falciparum malaria, MRI findings in the brain were correlated with clinical and laboratory parameters, retinal photography and optic nerve sheath diameter (ONSD) ultrasound (a marker of intracranial pressure).
Of 43 enrolled patients, 31 (72%) had coma and 12 (28%) died. MRI abnormalities were present in 79% overall with mostly mild changes in a wide range of anatomical sites. There were no differences in MRI findings between patients with cerebral and non-cerebral or fatal and non-fatal disease. Subtle diffuse cerebral swelling was common (n = 22/43), but mostly without vasogenic oedema or raised intracranial pressure (ONSD). Also seen were focal extracellular oedema (n = 11/43), cytotoxic oedema (n = 8/23) and mildly raised brain lactate on magnetic resonance spectroscopy (n = 5/14). Abnormalities were much less prominent than previously described in Malawian children. Retinal whitening was present in 36/43 (84%) patients and was more common and severe in patients with coma.
Cerebral swelling is mild and not specific to coma or death in adult severe falciparum malaria. This differs markedly from African children. Retinal whitening, reflecting heterogeneous obstruction of the central nervous system microcirculation by sequestered parasites resulting in small patches of ischemia, is associated with coma and this process is likely important in the pathogenesis.
PMCID: PMC4024626  PMID: 24884982
MRI; Falciparum; Cerebral; Retinopathy; Pathophysiology
In vitro antimalarial drug susceptibility is conventionally assessed by the concentration dependent growth inhibition of Plasmodium in an in vitro culture system. Inhibition of the kinetic properties of the parasites could provide an alternative method to assess in vitro antimalarial drugs sensitivity. In this study we used a novel real time microscopic technique, which does not require fixation and staining of the parasite, to study the effects of antimalarial drugs on the intracellular movement of Plasmodium (P.) falciparum trophozoites. Using real time microscopy movement of P. falciparum pigment within erythrocytes was investigated before and after antimalarial drugs exposure (artesunate, quinine, and piperaquine). For artesunate, the 50% inhibition concentration (IC50) at which movement in half of the trophozoites was abolished was estimated by sigmoid curve fitting. Intra- and inter-observer agreements were also assessed. Healthy unexposed P. falciparum trophozoites in culture showed very active movement of malaria pigment. Quinine and piperaquine had no effect but artesunate did reduce pigment movement which started after 2.5 hours exposure to the drug. The mean (SD) IC50 for artesunate regarding abolishment of pigment movement was 54 (14) ng/ml. Assessments of intra- and inter-rater agreement showed good reproducibility of the technique (Kappa value 0.82 to 0.91). Abolishment of active movement of malaria pigment is an alternative approach to assess drug sensitivity for artesunate. Malaria pigment movement is abolished by artesunate early after exposure, but at concentrations higher than those inhibiting growth.
PMCID: PMC3808808  PMID: 23082547
Plasmodium falciparum; antimalarial drugs; pigment movement
3.  Randomized Controlled Trial of Levamisole Hydrochloride as Adjunctive Therapy in Severe Falciparum Malaria With High Parasitemia 
The Journal of Infectious Diseases  2013;209(1):120-129.
Background. Cytoadherence and sequestration of erythrocytes containing mature stages of Plasmodium falciparum are central to the pathogenesis of severe malaria. The oral anthelminthic drug levamisole inhibits cytoadherence in vitro and reduces sequestration of late-stage parasites in uncomplicated falciparum malaria treated with quinine.
Methods. Fifty-six adult patients with severe malaria and high parasitemia admitted to a referral hospital in Bangladesh were randomized to receive a single dose of levamisole hydrochloride (150 mg) or no adjuvant to antimalarial treatment with intravenous artesunate.
Results. Circulating late-stage parasites measured as the median area under the parasite clearance curves were 2150 (interquartile range [IQR], 0–28 025) parasites/µL × hour in patients treated with levamisole and 5489 (IQR, 192–25 848) parasites/µL × hour in controls (P = .25). The “sequestration ratios” at 6 and 12 hours for all parasite stages and changes in microvascular blood flow did not differ between treatment groups (all P > .40). The median time to normalization of plasma lactate (<2 mmol/L) was 24 (IQR, 12–30) hours with levamisole vs 28 (IQR, 12–36) hours without levamisole (P = .15).
Conclusions. There was no benefit of a single-dose of levamisole hydrochloride as adjuvant to intravenous artesunate in the treatment of adults with severe falciparum malaria. Rapid parasite killing by intravenous artesunate might obscure the effects of levamisole.
PMCID: PMC3864382  PMID: 23943850
malaria; severe; falciparum; sequestration; artesunate; levamisole
4.  Prognostic indicators in adults hospitalized with falciparum malaria in Western Thailand 
Malaria Journal  2013;12:229.
Severe malaria remains a major cause of death and morbidity amongst adults in the Asiatic tropics.
A retrospective analysis of the clinical and laboratory data of 988 adult patients, hospitalized with Plasmodium falciparum malaria and prospectively recruited to malaria studies in western Thailand between 1986 and 2002, was performed to assess the factors associated with a fatal outcome. Different severity scores and classifications for defining severe malaria were compared and, using multiple logistic regression, simple models for predicting mortality developed.
The proportion of patients fulfilling the WHO 2000 definition of severe malaria was 78.1%, and their mortality was 10%. Mortality in patients given parenteral artesunate or artemether (16/317, 5%) was lower than in those given parenteral quinine (59/442, 13%) (P < 0.001). Models using parameter sets based on WHO 1990, 2000 and Adapted AQ criteria plus blood smear parasite-stage assessment gave the best mortality prediction. A malaria prognostic index (MPI), derived from the dataset using five clinical or laboratory variables gave similar prognostic accuracy.
The mortality of severe malaria in adults has fallen and the switch from quinine to artesunate has probably been an important contributor. Prognostic indices based on WHO 2000 definitions, and other simpler indices based on fewer variables, provide clinically useful predictions of outcome in Asian adults with severe malaria.
PMCID: PMC3711784  PMID: 23829311
Malaria; Mortality; Thailand; Plasmodium falciparum; Prognosis
5.  Effect of High-Dose or Split-Dose Artesunate on Parasite Clearance in Artemisinin-Resistant Falciparum Malaria 
New treatment strategies are needed for artemisinin-resistant falciparum malaria. This randomized trial shows that neither increasing nor splitting the standard once-daily artesunate dose reverses the markedly reduced parasite clearance rate in patients with artemisinin-resistant falciparum malaria.
Background. The emergence of Plasmodium falciparum resistance to artemisinins on the Cambodian and Myanmar-Thai borders poses severe threats to malaria control. We investigated whether increasing or splitting the dose of the short-half-life drug artesunate improves parasite clearance in falciparum malaria in the 2 regions.
Methods. In Pailin, western Cambodia (from 2008 to 2010), and Wang Pha, northwestern Thailand (2009–2010), patients with uncomplicated falciparum malaria were randomized to oral artesunate 6 mg/kg/d as a once-daily or twice-daily dose for 7 days, or artesunate 8 mg/kg/d as a once-daily or twice-daily dose for 3 days, followed by mefloquine. Parasite clearance and recrudescence for up to 63 days of follow-up were assessed.
Results. A total of 159 patients were enrolled. Overall median (interquartile range [IQR]) parasitemia half-life (half-life) was 6.03 (4.89–7.28) hours in Pailin versus 3.42 (2.20–4.85) hours in Wang Pha (P = .0001). Splitting or increasing the artesunate dose did not shorten half-life in either site. Pharmacokinetic profiles of artesunate and dihydroartemisinin were similar between sites and did not correlate with half-life. Recrudescent infections occurred in 4 of 79 patients in Pailin and 5 of 80 in Wang Pha and was not different between treatment arms (P = .68).
Conclusions. Increasing the artesunate treatment dose up to 8 mg/kg/d or splitting the dose does not improve parasite clearance in either artemisinin resistant or more sensitive infections with P. falciparum.
Clinical Trials Registration. ISRCTN15351875.
PMCID: PMC3563392  PMID: 23175556
artemisinins; drug resistance; Plasmodium falciparum; neutropenia; reticulocytopenia
6.  Artemisinin Resistance in Plasmodium falciparum Malaria 
The New England journal of medicine  2009;361(5):455-467.
Artemisinin-based combination therapies are the recommended first-line treatments of falciparum malaria in all countries with endemic disease. There are recent concerns that the efficacy of such therapies has declined on the Thai–Cambodian border, historically a site of emerging antimalarial-drug resistance.
In two open-label, randomized trials, we compared the efficacies of two treatments for uncomplicated falciparum malaria in Pailin, western Cambodia, and Wang Pha, northwestern Thailand: oral artesunate given at a dose of 2 mg per kilogram of body weight per day, for 7 days, and artesunate given at a dose of 4 mg per kilogram per day, for 3 days, followed by mefloquine at two doses totaling 25 mg per kilogram. We assessed in vitro and in vivo Plasmodium falciparum susceptibility, artesunate pharmacokinetics, and molecular markers of resistance.
We studied 40 patients in each of the two locations. The overall median parasite clearance times were 84 hours (interquartile range, 60 to 96) in Pailin and 48 hours (interquartile range, 36 to 66) in Wang Pha (P<0.001). Recrudescence confirmed by means of polymerase-chain-reaction assay occurred in 6 of 20 patients (30%) receiving artesunate monotherapy and 1 of 20 (5%) receiving artesunate–mefloquine therapy in Pailin, as compared with 2 of 20 (10%) and 1 of 20 (5%), respectively, in Wang Pha (P = 0.31). These markedly different parasitologic responses were not explained by differences in age, artesunate or dihydroartemisinin pharmacokinetics, results of isotopic in vitro sensitivity tests, or putative molecular correlates of P. falciparum drug resistance (mutations or amplifications of the gene encoding a multidrug resistance protein [PfMDR1] or mutations in the gene encoding sarco–endoplasmic reticulum calcium ATPase6 [PfSERCA]). Adverse events were mild and did not differ significantly between the two treatment groups.
P. falciparum has reduced in vivo susceptibility to artesunate in western Cambodia as compared with northwestern Thailand. Resistance is characterized by slow parasite clearance in vivo without corresponding reductions on conventional in vitro susceptibility testing. Containment measures are urgently needed. ( number, NCT00493363, and Current Controlled Trials number, ISRCTN64835265.)
PMCID: PMC3495232  PMID: 19641202
7.  Defining Falciparum-Malaria-Attributable Severe Febrile Illness in Moderate-to-High Transmission Settings on the Basis of Plasma PfHRP2 Concentration 
The Journal of Infectious Diseases  2012;207(2):351-361.
Background. In malaria-endemic settings, asymptomatic parasitemia complicates the diagnosis of malaria. Histidine-rich protein 2 (HRP2) is produced by Plasmodium falciparum, and its plasma concentration reflects the total body parasite burden. We aimed to define the malaria-attributable fraction of severe febrile illness, using the distributions of plasma P. falciparum HRP2 (PfHRP2) concentrations from parasitemic children with different clinical presentations.
Methods. Plasma samples were collected from and peripheral blood slides prepared for 1435 children aged 6−60 months in communities and a nearby hospital in northeastern Tanzania. The study population included children with severe or uncomplicated malaria, asymptomatic carriers, and healthy control subjects who had negative results of rapid diagnostic tests. The distributions of plasma PfHRP2 concentrations among the different groups were used to model severe malaria-attributable disease.
Results. The plasma PfHRP2 concentration showed a close correlation with the severity of infection. PfHRP2 concentrations of >1000 ng/mL denoted a malaria-attributable fraction of severe disease of 99% (95% credible interval [CI], 96%–100%), with a sensitivity of 74% (95% CI, 72%–77%), whereas a concentration of <200 ng/mL denoted severe febrile illness of an alternative diagnosis in >10% (95% CI, 3%–27%) of patients. Bacteremia was more common among patients in the lowest and highest PfHRP2 concentration quintiles.
Conclusions. The plasma PfHRP2 concentration defines malaria-attributable disease and distinguishes severe malaria from coincidental parasitemia in African children in a moderate-to-high transmission setting.
PMCID: PMC3532834  PMID: 23136222
case definition; severe malaria; Plasmodium falciparum; histidine-rich protein 2; malaria-attributable disease; asymptomatic parasitemia; bacteremia; Tanzania
8.  Diagnosing Severe Falciparum Malaria in Parasitaemic African Children: A Prospective Evaluation of Plasma PfHRP2 Measurement 
PLoS Medicine  2012;9(8):e1001297.
Arjen Dondorp and colleagues investigate whether the plasma level of Plasmodium falciparum histidine-rich protein 2 can be used to distinguish between severe malaria and other severe febrile illness in African children with malaria.
In African children, distinguishing severe falciparum malaria from other severe febrile illnesses with coincidental Plasmodium falciparum parasitaemia is a major challenge. P. falciparum histidine-rich protein 2 (PfHRP2) is released by mature sequestered parasites and can be used to estimate the total parasite burden. We investigated the prognostic significance of plasma PfHRP2 and used it to estimate the malaria-attributable fraction in African children diagnosed with severe malaria.
Methods and Findings
Admission plasma PfHRP2 was measured prospectively in African children (from Mozambique, The Gambia, Kenya, Tanzania, Uganda, Rwanda, and the Democratic Republic of the Congo) aged 1 month to 15 years with severe febrile illness and a positive P. falciparum lactate dehydrogenase (pLDH)-based rapid test in a clinical trial comparing parenteral artesunate versus quinine (the AQUAMAT trial, ISRCTN 50258054). In 3,826 severely ill children, Plasmadium falciparum PfHRP2 was higher in patients with coma (p = 0.0209), acidosis (p<0.0001), and severe anaemia (p<0.0001). Admission geometric mean (95%CI) plasma PfHRP2 was 1,611 (1,350–1,922) ng/mL in fatal cases (n = 381) versus 1,046 (991–1,104) ng/mL in survivors (n = 3,445, p<0.0001), without differences in parasitaemia as assessed by microscopy. There was a U-shaped association between log10 plasma PfHRP2 and risk of death. Mortality increased 20% per log10 increase in PfHRP2 above 174 ng/mL (adjusted odds ratio [AOR] 1.21, 95%CI 1.05–1.39, p = 0.009). A mechanistic model assuming a PfHRP2-independent risk of death in non-malaria illness closely fitted the observed data and showed malaria-attributable mortality less than 50% with plasma PfHRP2≤174 ng/mL. The odds ratio (OR) for death in artesunate versus quinine-treated patients was 0.61 (95%CI 0.44–0.83, p = 0.0018) in the highest PfHRP2 tertile, whereas there was no difference in the lowest tertile (OR 1.05; 95%CI 0.69–1.61; p = 0.82). A limitation of the study is that some conclusions are drawn from a mechanistic model, which is inherently dependent on certain assumptions. However, a sensitivity analysis of the model indicated that the results were robust to a plausible range of parameter estimates. Further studies are needed to validate our findings.
Plasma PfHRP2 has prognostic significance in African children with severe falciparum malaria and provides a tool to stratify the risk of “true” severe malaria-attributable disease as opposed to other severe illnesses in parasitaemic African children.
Please see later in the article for the Editors' Summary.
Editors' Summary
Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected mosquitoes. In 2010, malaria caused an estimated 655,000 deaths worldwide, mostly in Africa, where according to the World Health Organization, one African child dies every minute from the disease. There are four Plasmodium parasite species that cause malaria in humans, with one species, Plasmodium falciparum, causing the most severe disease. However, diagnosing severe falciparum malaria in children living in endemic areas is problematic, as many semi-immune children may have the malaria parasites in their blood (described as being parasitaemic) but do not have clinical disease. Therefore, a positive malaria blood smear may be coincidental and not be diagnostic of severe malaria, and unfortunately, neither are the clinical symptoms of severe malaria, such as shock, acidosis, or coma, which can also be caused by other childhood infections. For these reasons, the misdiagnosis of falciparum malaria in severely ill children is an important problem in sub-Saharan Africa, and may result in unnecessary child deaths.
Why Was This Study Done?
Previous studies have suggested that a parasite protein—P. falciparum histidine-rich protein-2 (PfHRP2)—is a measure of the total number of parasites in the patient. Unlike the circulating parasites detected on a blood film, which do not represent the parasites that get stuck in vital organs, PfHRP2 is distributed equally through the total blood plasma volume, and so can be considered a measure of the total parasite burden in the previous 48 hours. So in this study, the researchers assessed the prognostic value of plasma PfHRP2 in African children with severe malaria and whether this protein could distinguish children who really do have severe malaria from those who have severe febrile illness but coincidental parasitaemia, who may have another infection.
What Did the Researchers Do and Find?
The researchers assessed levels of plasma PfHRP2 in 3,826 out of a possible 5,425 African children who participated in a large multinational trial (in Mozambique, The Gambia, Rwanda, Tanzania, Kenya, Uganda, and the Democratic Republic of Congo) that compared the anti-malarial drugs quinine and artesunate for the treatment of severe malaria. All children had a clinical diagnosis of severe malaria confirmed by a rapid diagnostic test, and the researchers used clinical signs to define the severity of malaria. The researchers assessed the relationship between plasma PfHRP2 concentrations and risk of death taking other well established predictors of death, such as coma, convulsions, hypoglycaemia, respiratory distress, and shock, into account.
The researchers found that PfHRP2 was detectable in 3,800/3,826 (99%) children with severe malaria and that the average plasma PfHRP2 levels was significantly higher in the 381 children who died from malaria than in children who survived (1,611 ng/mL versus 1,046 ng/mL). Plasma PfHRP2 was also significantly higher in children with severe malaria signs and symptoms such as coma, acidosis, and severe anaemia. Importantly, the researchers found that high death rates were associated with either very low or very high values of plasma PfHRP2: the odds (chance) of death were 20% higher per unit increase in PfHRP2 above a specific threshold (174 ng/ml), but below this concentration, the risk of death increased with decreasing levels, probably because at lower levels disease was caused by a severe febrile disease other than malaria, like septicemia. Finally, the researchers found that in children within the highest PfHRP2 tertile, the chance of death when treated with the antimalarial drug artesunate versus quinine was 0.61 but that there was no difference in death rates in the lowest tertile, which supports that patients with very low plasma PfHRP2 have a different severe febrile illness than malaria. The researchers use mathematical modeling to provide cut-off values for plasma PfHRP2 denoting the proportion of patients with a diagnosis other than severe malaria.
What Do These Findings Mean?
These findings suggest that in areas of moderate or high malaria transmission where a high proportion of children are parasitaemic, plasma PfHRP2 levels taken on admission to hospital can differentiate children at highest risk of death from severe falciparum malaria from those likely to have alternative causes of severe febrile illness. Therefore, plasma PfHRP2 could be considered a valuable additional diagnostic tool and prognostic indicator in African children with severe falciparum malaria. This finding is important for clinicians treating children with severe febrile illnesses in malaria-endemic countries: while high levels of plasma PfHRP2 is indicative of severe malaria which needs urgent antimalarial treatment, low levels suggest that another severe infective disease should be considered, warranting additional investigations and urgent treatment with antibiotics.
Additional Information
Please access these Web sites via the online version of this summary at
A previous small study in PLOS ONE explores the relationship between plasma PfHRP2 and severe malaria in Tanzanian children
The WHO website and the website of Malaria No More have comprehensive information about malaria
PMCID: PMC3424256  PMID: 22927801
9.  Sequence variation does not confound the measurement of plasma PfHRP2 concentration in African children presenting with severe malaria 
Malaria Journal  2012;11:276.
Plasmodium falciparum histidine-rich protein PFHRP2 measurement is used widely for diagnosis, and more recently for severity assessment in falciparum malaria. The Pfhrp2 gene is highly polymorphic, with deletion of the entire gene reported in both laboratory and field isolates. These issues potentially confound the interpretation of PFHRP2 measurements.
Studies designed to detect deletion of Pfhrp2 and its paralog Pfhrp3 were undertaken with samples from patients in seven countries contributing to the largest hospital-based severe malaria trial (AQUAMAT). The quantitative relationship between sequence polymorphism and PFHRP2 plasma concentration was examined in samples from selected sites in Mozambique and Tanzania.
There was no evidence for deletion of either Pfhrp2 or Pfhrp3 in the 77 samples with lowest PFHRP2 plasma concentrations across the seven countries. Pfhrp2 sequence diversity was very high with no haplotypes shared among 66 samples sequenced. There was no correlation between Pfhrp2 sequence length or repeat type and PFHRP2 plasma concentration.
These findings indicate that sequence polymorphism is not a significant cause of variation in PFHRP2 concentration in plasma samples from African children. This justifies the further development of plasma PFHRP2 concentration as a method for assessing African children who may have severe falciparum malaria. The data also add to the existing evidence base supporting the use of rapid diagnostic tests based on PFHRP2 detection.
PMCID: PMC3480887  PMID: 22898068
Malaria; Falciparum; Severe; Africa; Histidine-rich protein; Tandem repeat
10.  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 < .001). In an age- and antimalarial treatment–adjusted logistic regression model, significant, independent predictors for death were renal impairment, acidosis, parasitemia, and plasma PfHRP2 concentration.
Conclusions. Severe malaria in HIV-coinfected patients presents with higher parasite burden, more complications, and comorbidity, and carries a higher case fatality rate. Early identification of HIV coinfection is important for the clinical management of severe malaria.
PMCID: PMC3447636  PMID: 22752514
11.  Predicting the Clinical Outcome of Severe Falciparum Malaria in African Children: Findings From a Large Randomized Trial 
Four predictors were independently associated with an increased risk of death: acidosis, cerebral manifestations of malaria, elevated blood urea nitrogen, or signs of chronic illness. The standard base deficit was found to be the single most relevant predictor of death.
Background. Data from the largest randomized, controlled trial for the treatment of children hospitalized with severe malaria were used to identify such predictors of a poor outcome from severe malaria.
Methods. African children (<15 years) with severe malaria participated in a randomized comparison of parenteral artesunate and parenteral quinine in 9 African countries. Detailed clinical assessment was performed on admission. Parasite densities were assessed in a reference laboratory. Predictors of death were examined using a multivariate logistic regression model.
Results. Twenty indicators of disease severity were assessed, out of which 5 (base deficit, impaired consciousness, convulsions, elevated blood urea, and underlying chronic illness) were associated independently with death. Tachypnea, respiratory distress, deep breathing, shock, prostration, low pH, hyperparasitemia, severe anemia, and jaundice were statistically significant indicators of death in the univariate analysis but not in the multivariate model. Age, glucose levels, axillary temperature, parasite density, heart rate, blood pressure, and blackwater fever were not related to death in univariate models.
Conclusions. Acidosis, cerebral involvement, renal impairment, and chronic illness are key independent predictors for a poor outcome in African children with severe malaria. Mortality is markedly increased in cerebral malaria combined with acidosis.
Clinical Trial Registration. ISRCTN50258054.
PMCID: PMC3309889  PMID: 22412067
12.  Evaluation of a PfHRP2 and a pLDH-based Rapid Diagnostic Test for the Diagnosis of Severe Malaria in 2 Populations of African Children 
This comparative study in 1898 children in 2 different African population shows that a pfHRP2-based rapid diagnostic test is a reliable diagnostic for diagnosing severe falciparum malaria in these settings and performs better than routine microscopy or a pLDH based test.
Background. Rapid diagnostic tests (RDTs) now play an important role in the diagnosis of falciparum malaria in many countries where the disease is endemic. Although these tests have been extensively evaluated in uncomplicated falciparum malaria, reliable data on their performance for diagnosing potentially lethal severe malaria is lacking.
Methods. We compared a Plasmodium falciparum histidine-rich-protein2 (PfHRP2)–based RDT and a Plasmodium lactate dehydrogenase (pLDH)–based RDT with routine microscopy of a peripheral blood slide and expert microscopy as a reference standard for the diagnosis of severe malaria in 1898 children who presented with severe febrile illness at 2 centers in Mozambique and Tanzania.
Results. The overall sensitivity, specificity, positive predictive value, and negative predictive values of the PfHRP2-based test were 94.0%, 70.9%, 85.4%, and 86.8%, respectively, and for the pLDH-based test, the values were 88.0%, 88.3%, 93.2%, and 80.3%, respectively. At parasite counts <1000 parasites/μL (n = 173), sensitivity of the pLDH-based test was low (45.7%), compared with that of the PfHRP2-based test (69.9%). Both RDTs performed better than did the routine slide reading in a clinical laboratory as assessed in 1 of the centers.
Conclusion. The evaluated PfHRP2-based RDT is an acceptable alternative to routine microscopy for diagnosing severe malaria in African children and performed better than did the evaluated pLDH-based RDT.
PMCID: PMC3070869  PMID: 21467015
13.  Artesunate versus quinine in the treatment of severe falciparum malaria in African children (AQUAMAT): an open-label, randomised trial 
Lancet  2010;376(9753):1647-1657.
Severe malaria is a major cause of childhood death and often the main reason for paediatric hospital admission in sub-Saharan Africa. Quinine is still the established treatment of choice, although evidence from Asia suggests that artesunate is associated with a lower mortality. We compared parenteral treatment with either artesunate or quinine in African children with severe malaria.
This open-label, randomised trial was undertaken in 11 centres in nine African countries. Children (<15 years) with severe falciparum malaria were randomly assigned to parenteral artesunate or parenteral quinine. Randomisation was in blocks of 20, with study numbers corresponding to treatment allocations kept inside opaque sealed paper envelopes. The trial was open label at each site, and none of the investigators or trialists, apart from for the trial statistician, had access to the summaries of treatment allocations. The primary outcome measure was in-hospital mortality, analysed by intention to treat. This trial is registered, number ISRCTN50258054.
5425 children were enrolled; 2712 were assigned to artesunate and 2713 to quinine. All patients were analysed for the primary outcome. 230 (8·5%) patients assigned to artesunate treatment died compared with 297 (10·9%) assigned to quinine treatment (odds ratio [OR] stratified for study site 0·75, 95% CI 0·63–0·90; relative reduction 22·5%, 95% CI 8·1–36·9; p=0·0022). Incidence of neurological sequelae did not differ significantly between groups, but the development of coma (65/1832 [3·5%] with artesunate vs 91/1768 [5·1%] with quinine; OR 0·69 95% CI 0·49–0·95; p=0·0231), convulsions (224/2712 [8·3%] vs 273/2713 [10·1%]; OR 0·80, 0·66–0·97; p=0·0199), and deterioration of the coma score (166/2712 [6·1%] vs 208/2713 [7·7%]; OR 0·78, 0·64–0·97; p=0·0245) were all significantly less frequent in artesunate recipients than in quinine recipients. Post-treatment hypoglycaemia was also less frequent in patients assigned to artesunate than in those assigned to quinine (48/2712 [1·8%] vs 75/2713 [2·8%]; OR 0·63, 0·43–0·91; p=0·0134). Artesunate was well tolerated, with no serious drug-related adverse effects.
Artesunate substantially reduces mortality in African children with severe malaria. These data, together with a meta-analysis of all trials comparing artesunate and quinine, strongly suggest that parenteral artesunate should replace quinine as the treatment of choice for severe falciparum malaria worldwide.
The Wellcome Trust.
PMCID: PMC3033534  PMID: 21062666
14.  A Simplified, Low-Cost Method for Polarized Light Microscopy 
Malaria pigment is an intracellular inclusion body that appears in blood and tissue specimens on microscopic examination and can help in establishing the diagnosis of malaria. In simple light microscopy, it can be difficult to discern from cellular background and artifacts. It has long been known that if polarized light microscopy is used, malaria pigment can be much easier to distinguish. However, this technique is rarely used because of the need for a relatively costly polarization microscope. We describe a simple and economical technique to convert any standard light microscope suitable for examination of malaria films into a polarization microscope.
PMCID: PMC2843442  PMID: 19861611
15.  Taking Photographs with a Microscope 
We describe a simple, economical, and highly practical technique for taking digital photographs of specimens visualized through a light microscope. Most models of light microscope and compact digital camera, and even some cameraphones, can be used. The technique is quick to learn and can easily be performed in a resource-poor setting. It can be used to assist with diagnosis in remote areas and can be extremely useful for teaching.
PMCID: PMC2843439  PMID: 18784246
16.  Clinically uncomplicated Plasmodium falciparum malaria with high schizontaemia: A case report 
Malaria Journal  2008;7:57.
The treatment options for acute Plasmodium falciparum malaria are based on the clinician classifying the patient as uncomplicated or severe according to the clinical and parasitological findings. This process is not always straightforward.
Case presentation
An adult male presented to a clinic on the western border of Thailand with a physical examination and P. falciparum trophozoite count (1.2% of infected red blood cells, IRBC) from malaria blood smear, consistent with a diagnosis of uncomplicated P. falciparum infection. However, the physician on duty treated the patient for severe malaria based on the reported P. falciparum schizont count, which was very high (0.3% IRBC), noticeably in relation to the trophozoite count and schizont:trophozoite ratio 0.25:1. On intravenous artesunate, the patient deteriorated clinically in the first 24 hours. The trophozoite count increased from 1.2% IRBC at baseline to 20.5% IRBC 18 hours following the start of treatment. By day three, the patient recovered and was discharged on day seven having completed a seven-day treatment with artesunate and mefloquine.
The malaria blood smear provides only a guide to the overall parasite biomass in the body, due to the ability of P. falciparum to sequester in the microvasculature. In severe malaria, high schizont counts are associated with worse prognosis. In low transmission areas or in non-immune travelers the presence of schizonts in the peripheral circulation is an indication for close patient supervision. In this case, an unusually high schizont count in a clinically uncomplicated patient was indicative of potential deterioration. Prompt treatment with intravenous artesunate is likely to have been responsible for the good clinical outcome in this case.
PMCID: PMC2365953  PMID: 18402713
18.  Estimation of the Total Parasite Biomass in Acute Falciparum Malaria from Plasma PfHRP2 
PLoS Medicine  2005;2(8):e204.
In falciparum malaria sequestration of erythrocytes containing mature forms of Plasmodium falciparum in the microvasculature of vital organs is central to pathology, but quantitation of this hidden sequestered parasite load in vivo has not previously been possible. The peripheral blood parasite count measures only the circulating, relatively non-pathogenic parasite numbers. P. falciparum releases a specific histidine-rich protein (PfHRP2) into plasma. Quantitative measurement of plasma PfHRP2 concentrations may reflect the total parasite biomass in falciparum malaria.
Methods and Findings
We measured plasma concentrations of PfHRP2, using a quantitative antigen-capture enzyme-linked immunosorbent assay, in 337 adult patients with falciparum malaria of varying severity hospitalised on the Thai–Burmese border. Based on in vitro production rates, we constructed a model to link this measure to the total parasite burden in the patient. The estimated geometric mean parasite burden was 7 × 1011 (95% confidence interval [CI] 5.8 × 1011 to 8.5 × 1011) parasites per body, and was over six times higher in severe malaria (geometric mean 1.7 × 1012, 95% CI 1.3 × 1012 to 2.3 × 1012) than in patients hospitalised without signs of severity (geometric mean 2.8 × 1011, 95% CI 2.3 × 1011 to 3.5 × 1011; p < 0.001). Parasite burden was highest in patients who died (geometric mean 3.4 × 1012, 95% CI 1.9 × 1012 to 6.3 × 1012; p = 0.03). The calculated number of sequestered parasites increased with disease severity and was higher in patients with late developmental stages of P. falciparum present on peripheral blood smears. Comparing model and laboratory estimates of the time of sequestration suggested that admission to hospital with uncomplicated malaria often follows schizogony—but in severe malaria is unrelated to stage of parasite development.
Plasma PfHRP2 concentrations may be used to estimate the total body parasite biomass in acute falciparum malaria. Severe malaria results from extensive sequestration of parasitised erythrocytes.
Measuring sequestered parasites using plasma PfHRP2 concentrations may provide a more accurate estimate of total parasite mass and hence severity in falciparum malaria.
PMCID: PMC1188247  PMID: 16104831
19.  Artemether Bioavailability after Oral or Intramuscular Administration in Uncomplicated Falciparum Malaria 
Antimicrobial Agents and Chemotherapy  2003;47(12):3795-3798.
The antimalarial activity of artemether following oral or intramuscular administration in the plasma of 15 adults with acute uncomplicated Plasmodium falciparum malaria was measured by bioassay. The peak concentrations in plasma following oral administration were higher in patients with acute illness (median, 1,905 mmol of dihydroartemisinin [DHA] equivalents per liter; range, 955 to 3,358 mmol of DHA equivalents per liter) than in patients in the convalescent phase (median, 955 mmol of DHA equivalents per liter; range, 576 to 1,363 mmol of DHA equivalents per liter), and clearance (CL/F) was lower in patients in the acute phase (1.11 liters/kg/h; range, 0.21 to 3.08 liters/kg/h) than in patients in the convalescent phase (median, 2.76 liters/kg/h; range, 1.56 to 5.74 liters/kg/h) (P ≤ 0.008). Antimalarial activity in terms of the peak concentration in plasma (Cmax) after oral administration was a median of 16 times higher than that after intramuscular administration. The ratio of the area under the plasma concentration-time curve during the first 24 h (AUC0-24) after oral administration of artemether to the AUC0-24 after intramuscular administration was a median of 3.3 (range, 1 to 11) (P = 0.0001). In the acute phase, the time to Cmax was significantly shorter after oral administration (median, 1 h; range, 0.5 to 3.0 h) than after intramuscular administration (median, 8 h; range, 4 to 24 h) (P = 0.001). Intramuscular artemether is absorbed very slowly in patients with acute malaria.
PMCID: PMC296187  PMID: 14638485

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