Reduced Cardiac Index Reserve and Hypovolemia in Severe Falciparum Malaria.

BACKGROUND: Impaired microvascular perfusion is central to the development of coma and lactic acidosis in severe falciparum malaria. Refractory hypotension is rare on admission but develops frequently in fatal cases. We assessed cardiac function and volume status in severe falciparum malaria and its prognostic significance. METHODS: Patients with severe (N = 101) or acute uncomplicated falciparum malaria (N = 83) were recruited from 2 hospitals in India and Bangladesh, and healthy participants (N = 44) underwent echocardiography. RESULTS: Patients with severe malaria had 38% shorter left ventricular (LV) filling times and 25% shorter LV ejection times than healthy participants because of tachycardia; however, stroke volume, LV internal diameter in diastole (LVIDd), and LV internal diameter in systole (LVIDs) indices were similar. A low endocardial fraction shortening (eFS) was present in 17% (9 of 52) of severe malaria patients. Adjusting for preload and afterload, eFS was similar in health and severe malaria. Fatal cases had smaller baseline LVIDd and LVIDs indices, more collapsible inferior vena cavae (IVC), and higher heart rates than survivors. The LVIDs and IVC collapsibility were independent predictors for mortality, together with base excess and Glasgow Coma Scale. CONCLUSIONS: Patients with severe malaria have rapid ejection of a normal stroke volume. Fatal cases had features of relative hypovolemia and reduced cardiac index reserve.

Associations Between Restrictive Fluid Management and Renal Function and Tissue Perfusion in Adults With Severe Falciparum Malaria: A Prospective Observational Study.

BACKGROUND: Liberal fluid resuscitation has proved harmful in adults with severe malaria, but the level of restriction has not been defined. METHODS: In a prospective observational study in adults with severe falciparum malaria, restrictive fluid management was provided at the discretion of the treating physician. The relationships between the volume of fluid and changes in renal function or tissue perfusion were evaluated. RESULTS: A total of 154 patients were studied, 41 (26.6%) of whom died. Median total fluid intake during the first 6 and 24 hours from enrollment was 3.3 (interquartile range [IQR], 1.8-5.1) mL/kg per hour and 2.2 (IQR, 1.6-3.2) mL/kg per hour, respectively. Total fluid intake at 6 hours was not correlated with changes in plasma creatinine at 24 hours (n = 116; rs = 0.16; P = .089) or lactate at 6 hours (n = 94; rs = -0.05; P = .660). Development of hypotensive shock or pulmonary edema within 24 hours after enrollment were not related to the volume of fluid administration. CONCLUSIONS: Restrictive fluid management did not worsen kidney function and tissue perfusion in adult patients with severe falciparum malaria. We suggest crystalloid administration of 2-3 mL/kg per hour during the first 24 hours without bolus therapy, unless the patient is hypotensive.

Cell-Free Hemoglobin Is Associated With Increased Vascular Resistance and Reduced Peripheral Perfusion in Severe Malaria.

BACKGROUND: In severe falciparum malaria, unlike sepsis, hypotension on admission is uncommon. We hypothesized that low nitric oxide bioavailability due to the presence of cell-free hemoglobin (CFH) increases vascular tone in severe malaria. METHODS: Patients with severe malaria (n = 119), uncomplicated malaria (n = 91), or suspected bacterial sepsis (n = 56), as well as healthy participants (n = 50), were recruited. The systemic vascular resistance index (SVRI) was estimated from the echocardiographic cardiac index and the mean arterial pressure. RESULTS: SVRI and hematocrit levels were lower and plasma CFH and asymmetric dimethylarginine levels were higher in patients with malaria, compared with healthy participants. In multivariate linear regression models for mean arterial pressure or SVRI in patients with severe malaria, hematocrit and CFH but not asymmetric dimethylarginine were significant predictors. The SVRI was lower in patients with suspected bacterial sepsis than in those with severe malaria, after adjustment for hematocrit and age. Plasma CFH levels correlated positively with the core-peripheral temperature gradient and plasma lactate levels and inversely with the perfusion index. Impaired peripheral perfusion, as reflected by a low perfusion index or a high core-peripheral temperature gradient, predicted mortality in patients with severe malaria. CONCLUSIONS: CFH is associated with mean arterial pressure, SVRI, and peripheral perfusion in patients with severe malaria. This may be mediated through the nitric oxide scavenging potency of CFH, increasing basal vascular tone and impairing tissue perfusion.

Artemisinin Resistance and Stage Dependency of Parasite Clearance in Falciparum Malaria.

BACKGROUND: Artemisinin resistance in falciparum malaria is associated with kelch13 propeller mutations, reduced ring stage parasite killing, and, consequently, slow parasite clearance. We assessed how parasite age affects parasite clearance in artemisinin resistance. METHODS: Developmental stages of Plasmodium falciparum parasites on blood films performed at hospital admission and their kelch13 genotypes were assessed for 816 patients enrolled in a multinational clinical trial of artemisinin combination therapy. RESULTS: Early changes in parasitemia level (ie, 0-6 hours after admission) were determined mainly by modal stage of asexual parasite development, whereas the subsequent log-linear decline was determined mainly by kelch13 propeller mutations. Older circulating parasites on admission were associated with more-rapid parasite clearance, particularly in kelch13 mutant infections. The geometric mean parasite clearance half-life decreased by 11.6% (95% CI 3.4%-19.1%) in kelch13 wild-type infections and by 30% (95% CI 17.8%-40.4%) in kelch13 mutant infections as the mean age of circulating parasites rose from 3 to 21 hours. CONCLUSION: Following the start of antimalarial treatment, ongoing parasite sequestration and schizogony both affect initial changes in parasitemia. The greater dependency of parasite clearance half-life on parasite age in artemisinin resistant infections is consistent with ring stage resistance and consequent parasite clearance by sequestration. The stage of parasite development should be incorporated in individual assessments of artemisinin resistance.

Identifying the Components of Acidosis in Patients With Severe Plasmodium falciparum Malaria Using Metabolomics.

BACKGROUND: Acidosis in severe Plasmodium falciparum malaria is associated with high mortality, yet the pathogenesis remains incompletely understood. The aim of this study was to determine the nature and source of metabolic acids contributing to acidosis in patients with severe falciparum malaria. METHODS: A prospective observational study was conducted to characterize circulating acids in adults with P. falciparum malaria (n = 107) and healthy controls (n = 45) from Bangladesh using high-resolution liquid chromatography-mass spectrometry metabolomics. Additional in vitro P. falciparum culture studies were performed to determine if parasites release the acids detected in plasma from patients with severe malaria acidosis. RESULTS: We identified previously unmeasured plasma acids strongly associated with acidosis in severe malaria. Metabolomic analysis of P. falciparum parasites in vitro showed no evidence that these acids are released by the parasite during its life cycle. Instead, 10 of the plasma acids could be mapped to a gut microbial origin. Patients with malaria had low L-citrulline levels, a plasma marker indicating reduced gut barrier integrity. Longitudinal data showed the clearance of these newly identified acids was delayed in fatal cases. CONCLUSIONS: These data suggest that a compromise in intestinal barrier function may contribute significantly to the pathogenesis of life-threatening acidosis in severe falciparum malaria. CLINICAL TRIALS REGISTRATION: NCT02451904.

Does reduced oxygen delivery cause lactic acidosis in falciparum malaria? An observational study.

BACKGROUND: Lactic acidosis with an elevated lactate-pyruvate ratio suggesting anoxia is a common feature of severe falciparum malaria. High lactate levels are associated with parasitized erythrocyte sequestration in the microcirculation. To assess if there is an additional contribution to hyperlactataemia from relatively inadequate total oxygen delivery, oxygen consumption and delivery were investigated in patients with malaria. METHODS: Adult Bangladeshi and Indian patients with uncomplicated (N = 50) or severe (N = 46) falciparum malaria or suspected bacterial sepsis (N = 27) and healthy participants as controls (N = 26) were recruited at Chittagong Medical College Hospital, Chittagong, Bangladesh and Ispat General Hospital, Rourkela, India. Oxygen delivery (DO2I) was estimated from pulse oximetry, echocardiographic estimates of cardiac index and haematocrit. Oxygen consumption (VO2I) was estimated by expired gas collection. RESULTS: VO2I was elevated in uncomplicated median (IQR) 185.1 ml/min/m2 (135-215.9) and severe malaria 192 ml/min/m2 (140.7-227.9) relative to healthy persons 107.9 ml/min/m2 (69.9-138.1) (both p < 0.001). Median DO2I was similar in uncomplicated 515 ml/min/m2 (432-612) and severe 487 ml/min/m2 (382-601) malaria and healthy persons 503 ml/min/m2 (447-517) (p = 0.27 and 0.89, respectively). The VO2/DO2 ratio was, therefore, increased by similar amounts in both uncomplicated 0.35 (0.28-0.44) and severe malaria 0.38 (0.29-0.48) relative to healthy participants 0.23 (0.17-0.28) (both p < 0.001). VO2I, DO2I and VO2/DO2 did not correlate with plasma lactate concentrations in severe malaria. CONCLUSIONS: Reduced total oxygen delivery is not a major contributor to lactic acidosis in severe falciparum malaria.

Acetaminophen as a Renoprotective Adjunctive Treatment in Patients With Severe and Moderately Severe Falciparum Malaria: A Randomized, Controlled, Open-Label Trial.

Background: Acute kidney injury independently predicts mortality in falciparum malaria. It is unknown whether acetaminophen's capacity to inhibit plasma hemoglobin-mediated oxidation is renoprotective in severe malaria. Methods: This phase 2, open-label, randomized controlled trial conducted at two hospitals in Bangladesh assessed effects on renal function, safety, pharmacokinetic (PK) properties and pharmacodynamic (PD) effects of acetaminophen. Febrile patients (>12 years) with severe falciparum malaria were randomly assigned to receive acetaminophen (1 g 6-hourly for 72 hours) or no acetaminophen, in addition to intravenous artesunate. Primary outcome was the proportional change in creatinine after 72 hours stratified by median plasma hemoglobin. Results: Between 2012 and 2014, 62 patients were randomly assigned to receive acetaminophen (n = 31) or no acetaminophen (n = 31). Median (interquartile range) reduction in creatinine after 72 hours was 23% (37% to 18%) in patients assigned to acetaminophen, versus 14% (29% to 0%) in patients assigned to no acetaminophen (P = .043). This difference in reduction was 37% (48% to 22%) versus 14% (30% to -71%) in patients with hemoglobin ≥45000 ng/mL (P = .010). The proportion with progressing kidney injury was higher among controls (subdistribution hazard ratio, 3.0; 95% confidence interval, 1.1 to 8.5; P = .034). PK-PD analyses showed that higher exposure to acetaminophen increased the probability of creatinine improvement. No patient fulfilled Hy's law for hepatotoxicity. Conclusions: In this proof-of-principle study, acetaminophen showed renoprotection without evidence of safety concerns in patients with severe falciparum malaria, particularly in those with prominent intravascular hemolysis. Clinical Trials Registration: NCT01641289.

Rickettsial Illnesses as Important Causes of Febrile Illness in Chittagong, Bangladesh.

We conducted a yearlong prospective study of febrile patients admitted to a tertiary referral hospital in Chittagong, Bangladesh, to assess the proportion of patients with rickettsial illnesses and identify the causative pathogens, strain genotypes, and associated seasonality patterns. We diagnosed scrub typhus in 16.8% (70/416) and murine typhus in 5.8% (24/416) of patients; 2 patients had infections attributable to undifferentiated Rickettsia spp. and 2 had DNA sequence-confirmed R. felis infection. Orientia tsutsugamushi genotypes included Karp, Gilliam, Kato, and TA763-like strains, with a prominence of Karp-like strains. Scrub typhus admissions peaked in a biphasic pattern before and after the rainy season, whereas murine typhus more frequently occurred before the rainy season. Death occurred in 4% (18/416) of cases; case-fatality rates were 4% each for scrub typhus (3/70) and murine typhus (1/28). Overall, 23.1% (96/416) of patients had evidence of treatable rickettsial illnesses, providing important evidence toward optimizing empirical treatment strategies.

Genotypic and phenotypic characterization of G6PD deficiency in Bengali adults with severe and uncomplicated malaria.

BACKGROUND: Control of malaria increasingly involves administration of 8-aminoquinolines, with accompanying risk of haemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Few data on the prevalence and genotypic basis of G6PD deficiency are available from Bangladesh, where malaria remains a major problem in the South (Chittagong Division). The aim of this study was to determine the prevalence of G6PD deficiency, and associated G6PD genotypes, in adults with falciparum malaria in southern Bangladesh. METHODS: G6PD status was assessed via a combination of fluorescent spot testing (FST) and genotyping in 141 Bengali patients admitted with falciparum malaria to two centres in Chittagong Division from 2012 to 2014. In addition, an analysis of genomic data from 1000 Genomes Project was carried out among five healthy Indian subcontinent populations. RESULTS: One male patient with uncomplicated malaria was found to have G6PD deficiency on FST and a genotype associated with deficiency (hemizygous Orissa variant). In addition, there were two female patients heterozygous for deficiency variants (Orissa and Kerala-Kalyan). These three patients had a relatively long duration of symptoms prior to admission compared to G6PD normal cases, possibly suggesting an interaction with parasite multiplication rate. In addition, one of 27 healthy local controls was deficient on FST and hemizygous for the Mahidol variant of G6PD deficiency. Examination of 1000 Genomes Project sequencing data across the Indian subcontinent showed that 19/723 chromosomes (2.63%) carried a variant associated with deficiency. In the Bengali from Bangladesh 1000 Genomes population, three of 130 chromosomes (2.31%) carried deficient alleles; this included single chromosomes carrying the Kerala-Kalyan and Orissa variants. CONCLUSIONS: In line with other recent work, G6PD deficiency is uncommon in Bengalis in Bangladesh. Further studies of particular ethnic groups are needed to evaluate the potential risk of wide deployment of primaquine in malaria control efforts in Bangladesh.

Cell-free hemoglobin mediated oxidative stress is associated with acute kidney injury and renal replacement therapy in severe falciparum malaria: an observational study.

BACKGROUND: Intravascular hemolysis is an intrinsic feature of severe malaria pathophysiology but the pathogenic role of cell-free hemoglobin-mediated oxidative stress in severe malaria associated acute kidney injury (AKI) is unknown. METHODS: As part of a prospective observational study, enrolment plasma cell-free hemoglobin (CFH), lipid peroxidation markers (F2-isoprostanes (F2-IsoPs) and isofurans (IsoFs)), red cell deformability, and serum creatinine were quantified in Bangladeshi patients with severe falciparum malaria (n = 107), uncomplicated malaria (n = 80) and sepsis (n = 28). The relationships between these indices and kidney function and clinical outcomes were examined. RESULTS: AKI was diagnosed at enrolment in 58% (62/107) of consecutive patients with severe malaria, defined by an increase in creatinine ≥1.5 times expected baseline. Severe malaria patients with AKI had significantly higher plasma cell-free hemoglobin (geometric mean CFH: 8.8 µM; 95% CI, 6.2-12.3 µM), F2-isoprostane (56.7 pg/ml; 95% CI, 45.3-71.0 pg/ml) and isofuran (109.2 pg/ml; 95% CI, 85.1-140.1 pg/ml) concentrations on enrolment compared to those without AKI (CFH: 5.1 µM; 95% CI, 4.0-6.6 µM; P = 0.018; F2-IsoPs: 27.8 pg/ml; 95% CI, 23.7-32.7 pg/ml; P < 0.001; IsoFs: 41.7 pg/ml; 95% CI, 30.2-57.6 pg/ml; P < 0.001). Cell-free hemoglobin correlated with markers of hemolysis, parasite burden (P. falciparum histidine rich protein 2 (PfHRP2)), and F2-IsoPs. Plasma F2-IsoPs and IsoFs inversely correlated with pH, positively correlated with creatinine, PfHRP2 and fractional excretion of sodium, and were higher in patients later requiring hemodialysis. Plasma F2-IsoP concentrations also inversely correlated with red cell deformability and were higher in fatal cases. Mixed effects modeling including an interaction term for CFH and time showed that F2-IsoPs, IsoFs, PfHRP2, CFH, and red cell rigidity were independently associated with increasing creatinine over 72 h. Multivariable logistic regression showed that admission F2-IsoPs, IsoFs and red cell deformability were associated with the need for subsequent hemodialysis. CONCLUSIONS: Cell-free hemoglobin and lipid peroxidation are associated with acute kidney injury and disease severity in falciparum malaria, suggesting a pathophysiological role in renal tubular injury. Evaluation of adjunctive therapies targeting cell-free hemoglobin-mediated oxidative stress is warranted.

The clinical implications of thrombocytopenia in adults with severe falciparum malaria: a retrospective analysis.

BACKGROUND: Thrombocytopenia is a common finding in adults with severe falciparum malaria, but its clinical and prognostic utility is incompletely defined. METHODS: Clinical and laboratory data from 647 adults with severe falciparum malaria were analysed retrospectively to determine the relationship between a patient's platelet count on admission to hospital and their subsequent clinical course. RESULTS: On admission, 614 patients (94.9%) were thrombocytopenic (platelet count <150 × 10(9)/L) and 328 (50.7%) had a platelet count <50 × 10(9)/L. The admission platelet count was inversely correlated with parasite biomass (estimated from plasma PfHRP2 concentrations, rs = -0.28, P = 0.003), the degree of microvascular sequestration (measured with orthogonal polarizing spectral imaging, rs = -0.31, P = 0.001) and disease severity (the number of World Health Organization severity criteria satisfied by the patient, rs = -0.21, P <0.001). Platelet counts were lower on admission in the patients who died (median: 30 (interquartile range 22 to 52) × 10(9)/L versus 50 (34 to 78) × 10(9)/L in survivors; P <0.001), but did not predict outcome independently from other established laboratory and clinical prognostic indices. The 39 patients (6%) with profound thrombocytopenia (platelet count <20 × 10(9)/L) were more likely to die (odds ratio: 5.00, 95% confidence interval: 2.56 to 9.75) than patients with higher platelet counts, but these high-risk patients could be identified more rapidly with simple bedside clinical assessment. The admission platelet count did not reliably identify the 50 patients (7.7%) with major bleeding during the study. CONCLUSIONS: Thrombocytopenia is a marker of disease severity in adults with falciparum malaria, but has limited utility in prognostication, triage and management.

Microvascular obstruction and endothelial activation are independently associated with the clinical manifestations of severe falciparum malaria in adults: an observational study.

BACKGROUND: Microvascular obstruction and endothelial dysfunction have both been linked to tissue hypoperfusion in falciparum malaria, but their relative contributions to the disease's pathogenesis and outcome are unknown. METHODS: Microvascular blood flow was quantified in adults with severe falciparum malaria on their admission to hospital; plasma biomarkers of endothelial function were measured simultaneously. The relationship between these indices and the patients' clinical findings and in-hospital course was examined. RESULTS: Microvascular obstruction was observed in 119/142 (84 %) patients; a median (interquartile range (IQR)) of 14.9 % (6.6-34.9 %) of capillaries were obstructed in patients that died versus 8.3 % (1.7-26.6 %) in survivors (P = 0.039). The proportion of obstructed capillaries correlated with the estimated parasite biomass (rs = 0.25, P = 0.004) and with plasma lactate (rs = 0.38, P <0.0001), the strongest predictor of death in the series. Plasma angiopoietin-2 (Ang-2) concentrations were markedly elevated suggesting widespread endothelial activation; the median (IQR) Ang-2 concentration was 21.9 ng/mL (13.4-29.4 ng/mL) in patients that died versus 14.9 ng/mL (9.8-29.3 ng/mL) in survivors (P = 0.035). Ang-2 concentrations correlated with estimated parasite biomass (rs = 0.35, P <0.001) and plasma lactate (rs = 0.37, P <0.0001). Microvascular obstruction and Ang-2 concentrations were not significantly correlated with each other (rs = 0.17, P = 0.06), but were independently associated with plasma lactate (P <0.001 and P = 0.002, respectively). CONCLUSIONS: Microvascular obstruction and systemic endothelial activation are independently associated with plasma lactate, the strongest predictor of death in adults with falciparum malaria. This supports the hypothesis that the two processes make an independent contribution to the pathogenesis and clinical manifestations of the disease.

Severe falciparum malaria treated with artesunate complicated by delayed onset haemolysis and acute kidney injury.

BACKGROUND: Severe falciparum malaria may be complicated by haemolysis after parasite clearance, however the mechanisms remain unclear. Recent reports describe a pattern of delayed onset haemolysis among non-immune travellers with hyperparasitaemia treated with intravenous artesunate, termed post-artesunate delayed haemolysis (PADH). The occurrence and clinical impact of PADH following severe malaria infections in areas of unstable transmission are unknown. CASE: A 45-year-old Bangladeshi male was initially admitted to a local hospital with severe falciparum malaria complicated by hyperparasitaemia and treated with intravenous artesunate. Twenty days from his first presentation he was readmitted with delayed onset haemolytic anaemia and acute kidney injury. Multiple blood transfusions and haemodialysis were required. Renal biopsy revealed acute tubular injury and haem pigment nephropathy. His haemoglobin and renal function recovered to baseline after 62 days from his second admission. DISCUSSION: This case highlights the differential diagnosis of post-malaria delayed onset haemolysis, including the recently described syndrome of post-artemisinin delayed haemolysis. The pathophysiology contributing to acute kidney injury in this patient and the limited treatment options are discussed. CONCLUSIONS: This report describes PADH complicated by acute kidney injury in an adult patient living in a malaria hypoendemic region who subsequently required blood transfusions and haemodialysis. This case emphasizes the importance of routine follow up of haemoglobin and renal function in artesunate-treated patients who have recovered from severe malaria.

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

INTRODUCTION: Severe 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. METHODS: In 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. RESULTS: Patients 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 ß-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). CONCLUSIONS: Newly 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.

Malaria: What's New in the Management of Malaria?

The global burden of malaria remains high, with 216 million cases causing 445,000 deaths in 2016 despite first-line treatment with artemisinin-based combination therapy. Decreasing transmission in Africa shifts the risk for severe malaria to older age groups as premunition wanes. Prompt diagnosis and treatment with intravenous artesunate in addition to appropriate supportive management are critical to reduce deaths from severe malaria. Effective individual management is challenging in settings with limited resources for higher-level care. Adjunctive therapies targeting the underlying pathophysiological pathways have the potential to reduce mortality. Resistance to artemisinin derivatives and their partner drugs threaten malaria management and control.

Amino acid derangements in adults with severe falciparum malaria.

Amino acid derangements are common in severe falciparum malaria and have been associated with endothelial dysfunction (L-arginine), metabolic acidosis (alanine and lactate), and disease severity (phenylalanine and tryptophan metabolites). Whether these amino acid perturbations reflect isolated pathogenic mechanisms or if they are part of overall changes in amino acid metabolism is unclear. To investigate this, we prospectively simultaneously quantified a broad range of plasma free amino acids (PFAA) using HPLC-MRM-Mass spectrometry in relation to presenting symptoms in adults with severe malaria (n = 88), septicaemia (n = 88), uncomplicated malaria (n = 71), and healthy controls (n = 48) from Bangladesh. The total plasma concentration of measured amino acids was significantly reduced in each of the patient groups when compared to normal levels observed in healthy local controls: uncomplicated malaria -54%, severe malaria -23%, and sepsis -32%, (p = <0.001). Inspection of amino acid profiles revealed that in each group the majority of amino acids were below normal levels, except for phenylalanine. Among patients with severe malaria, L-lactate was strongly associated with an increase of the total amino acid concentration, likely because this reflects tissue hypoxia. Our data confirm previously described amino acid abnormalities, likely resulting from overall changes in the concentration of PFAA.

Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh.

Here we estimated the accuracy of the InBios Scrub Typhus Detect™ immunoglobulin M (IgM) ELISA to determine the optimal optical density (OD) cut-off values for the diagnosis of scrub typhus. Patients with undifferentiated febrile illness from Chittagong, Bangladesh, provided samples for reference testing using (i) qPCR using the Orientia spp. 47-kDa htra gene, (ii) IFA ≥1:3200 on admission, (iii) immunofluorescence assay (IFA) ≥1:3200 on admission or 4-fold rise to ≥3200, and (iv) combination of PCR and IFA positivity. For sero-epidemiological purposes (ELISA vs. IFA ≥1:3200 on admission or 4-fold rise to ≥3200), the OD cut-off for admission samples was ≥1.25, resulting in a sensitivity (Sn) of 91.5 (95% confidence interval (95% CI: 96.8⁻82.5) and a specificity (Sp) of 92.4 (95% CI: 95.0⁻89.0), while for convalescent samples the OD cut-off was ≥1.50 with Sn of 66.0 (95% CI: 78.5⁻51.7) and Sp of 96.0 (95% CI: 98.3⁻92.3). Comparisons against comparator reference tests (ELISA vs. all tests including PCR) indicated the most appropriate cut-off OD to be within the range of 0.75⁻1.25. For admission samples, the best Sn/Sp compromise was at 1.25 OD (Sn 91.5%, Sp 92.4%) and for convalescent samples at 0.75 OD (Sn 69.8%, Sp 89.5%). A relatively high (stringent) diagnostic cut-off value provides increased diagnostic accuracy with high sensitivity and specificity in the majority of cases, while lowering the cut-off runs the risk of false positivity. This study underlines the need for regional assessment of new diagnostic tests according to the level of endemicity of the disease given the high levels of residual or cross-reacting antibodies in the general population.

Point-of-care lung ultrasound for the detection of pulmonary manifestations of malaria and sepsis: An observational study.

INTRODUCTION: Patients with severe malaria or sepsis are at risk of developing life-threatening acute respiratory distress syndrome (ARDS). The objective of this study was to evaluate point-of-care lung ultrasound as a novel tool to determine the prevalence and early signs of ARDS in a resource-limited setting among patients with severe malaria or sepsis. MATERIALS AND METHODS: Serial point-of-care lung ultrasound studies were performed on four consecutive days in a planned sub study of an observational cohort of patients with malaria or sepsis in Bangladesh. We quantified aeration patterns across 12 lung regions. ARDS was defined according to the Kigali Modification of the Berlin Definition. RESULTS: Of 102 patients enrolled, 71 had sepsis and 31 had malaria. Normal lung ultrasound findings were observed in 44 patients on enrolment and associated with 7% case fatality. ARDS was detected in 10 patients on enrolment and associated with 90% case fatality. All patients with ARDS had sepsis, 4 had underlying pneumonia. Two patients developing ARDS during hospitalisation already had reduced aeration patterns on enrolment. The SpO2/FiO2 ratio combined with the number of regions with reduced aeration was a strong prognosticator for mortality in patients with sepsis (AUROC 91.5% (95% Confidence Interval: 84.6%-98.4%)). CONCLUSIONS: This study demonstrates the potential usefulness of point-of-care lung ultrasound to detect lung abnormalities in patients with malaria or sepsis in a resource-constrained hospital setting. LUS was highly feasible and allowed to accurately identify patients at risk of death in a resource limited setting.

Disease Severity and Effective Parasite Multiplication Rate in Falciparum Malaria.

Patients presenting with severe falciparum malaria in a Bangladeshi tertiary hospital had higher total parasite burden, estimated by parasitemia and plasma PfHRP2, than uncomplicated malaria patients despite shorter fever duration. This suggests that higher parasite multiplication rates (PMR) contribute to causing the higher biomass found in severe disease. Compared with patients without a history of previous malaria, patients with previous malaria carried a lower parasite biomass with similar fever duration at presentation, suggesting that host immunity reduces the PMR.