M. Abul Faiz

Spread of artemisinin-resistant Plasmodium falciparum in Myanmar: a cross-sectional survey of the K13 molecular marker

Summary Background Emergence of artemisinin resistance in southeast Asia poses a serious threat to the global control of Plasmodium falciparum malaria. Discovery of the K13 marker has transformed approaches to the monitoring of artemisinin resistance, allowing introduction of molecular surveillance in remote areas through analysis of DNA. We aimed to assess the spread of artemisinin-resistant P falciparum in Myanmar by determining the relative prevalence of P falciparum parasites carrying K13-propeller mutations. Methods We did this cross-sectional survey at malaria treatment centres at 55 sites in ten administrative regions in Myanmar, and in relevant border regions in Thailand and Bangladesh, between January, 2013, and September, 2014. K13 sequences from P falciparum infections were obtained mainly by passive case detection. We entered data into two geostatistical models to produce predictive maps of the estimated prevalence of mutations of the K13 propeller region across Myanmar. Findings Overall, 371 (39%) of 940 samples carried a K13-propeller mutation. We recorded 26 different mutations, including nine mutations not described previously in southeast Asia. In seven (70%) of the ten administrative regions of Myanmar, the combined K13-mutation prevalence was more than 20%. Geospatial mapping showed that the overall prevalence of K13 mutations exceeded 10% in much of the east and north of the country. In Homalin, Sagaing Region, 25 km from the Indian border, 21 (47%) of 45 parasite samples carried K13-propeller mutations. Interpretation Artemisinin resistance extends across much of Myanmar. We recorded P falciparum parasites carrying K13-propeller mutations at high prevalence next to the northwestern border with India. Appropriate therapeutic regimens should be tested urgently and implemented comprehensively if spread of artemisinin resistance to other regions is to be avoided. Funding Wellcome Trust–Mahidol University–Oxford Tropical Medicine Research Programme and the Bill & Melinda Gates Foundation.

N-Acetylcysteine as adjunctive treatment in severe malaria: A randomized double blinded placebo controlled clinical trial

Objective:Markers of oxidative stress are reported to be increased in severe malaria. It has been suggested that the antioxidant N-acetylcysteine (NAC) may be beneficial in treatment. We studied the efficacy and safety of parenteral NAC as an adjunct to artesunate treatment of severe falciparum malaria. Design:A randomized, double-blind, placebo-controlled trial on the use of high-dose intravenous NAC as adjunctive treatment to artesunate. Setting:A provincial hospital in Western Thailand and a tertiary referral hospital in Chittagong, Bangladesh. Patients:One hundred eight adult patients with severe falciparum malaria. Interventions:Patients were randomized to receive NAC or placebo as an adjunctive treatment to intravenous artesunate. Measurements and Main Results:A total of 56 patients were treated with NAC and 52 received placebo. NAC had no significant effect on mortality, lactate clearance times (p = 0.74), or coma recovery times (p = 0.46). Parasite clearance time was increased from 30 hours (range, 6–144 hours) to 36 hours (range, 6–120 hours) (p = 0.03), but this could be explained by differences in admission parasitemia. Urinary F2-isoprostane metabolites, measured as a marker of oxidative stress, were increased in severe malaria compared with patients with uncomplicated malaria and healthy volunteers. Admission red cell rigidity correlated with mortality, but did not improve with NAC. Conclusion:Systemic oxidative stress is increased in severe malaria. Treatment with NAC had no effect on outcome in patients with severe falciparum malaria in this setting.

The spectrum of retinopathy in adults with Plasmodium falciparum malaria

Summary A specific retinopathy has been described in African children with cerebral malaria, but in adults this has not been extensively studied. Since the structure and function of the retinal vasculature greatly resembles the cerebral vasculature, study of retinal changes can reveal insights into the pathophysiology of cerebral malaria. A detailed observational study of malarial retinopathy in Bangladeshi adults was performed using high-definition portable retinal photography. Retinopathy was present in 17/27 adults (63%) with severe malaria and 14/20 adults (70%) with cerebral malaria. Moderate or severe retinopathy was more frequent in cerebral malaria (11/20, 55%) than in uncomplicated malaria (3/15, 20%; P = 0.039), bacterial sepsis (0/5, 0%; P = 0.038) or healthy controls (0/18, 0%; P < 0.001). The spectrum of malarial retinopathy was similar to that previously described in African children, but no vessel discolouration was observed. The severity of retinal whitening correlated with admission venous plasma lactate (P = 0.046), suggesting that retinal ischaemia represents systemic ischaemia. In conclusion, retinal changes related to microvascular obstruction were common in adults with severe falciparum malaria and correlated with disease severity and coma, suggesting that a compromised microcirculation has important pathophysiological significance in severe and cerebral malaria. Portable retinal photography has potential as a valuable tool to study malarial retinopathy.

A randomized controlled trial on the efficacy of alternative treatment regimens for uncomplicated falciparum malaria in a multidrug-resistant falciparum area of Bangladesh--narrowing the options for the National Malaria Control Programme?

We performed an open, randomized chemotherapy trial comparing the recommended first-, second- and third-line drug regimens, as well as mefloquine, for uncomplicated falciparum malaria in Bangladesh in 1996-97. The regimens were chloroquine for 3 days (CQ, Group I), quinine sulphate for 3 days followed by single-dose sulfadoxine-pyrimethamine (Q3 + SP, Group II), quinine for 7 days (Q7, Group III), and mefloquine 20 mg/kg single dose (MEF, Group IV). Subjects were symptomatic patients, aged > or = 12 years, with parasite density 500-250,000/mm3 and no history of taking antimalarials during the previous week. Drug administration was supervised and subjects were followed clinically and with blood slides in the hospital for 8 days, then as outpatients on days 14, 21 and 28. A total of 413 subjects (149, 145, 49 and 70 in Groups I-IV, respectively) completed the study. Early treatment failures (persistent or worsening clinical manifestations by day 3 confirmed with parasitological examinations) occurred only in the chloroquine group. RII and RIII parasitological failures occurred in 56%, 12%, 8% and 14% in Group I-IV, respectively. There were significantly more clinical and parasitological failures with chloroquine than with Q3 + SP, which we now recommend as a better (but far from ideal) choice for first-line therapy. The alternative compounds show parasitogical evidence of Plasmodium falciparum resistance. Further studies are needed to determine the optimum treatment for malaria in Bangladesh.

Randomized Controlled Trial of Levamisole Hydrochloride as Adjunctive Therapy in Severe Falciparum Malaria With High Parasitemia

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.

Timing of Enteral Feeding in Cerebral Malaria in Resource-Poor Settings: A Randomized Trial

Background Early start of enteral feeding is an established treatment strategy in intubated patients in intensive care since it reduces invasive bacterial infections and length of hospital stay. There is equipoise whether early enteral feeding is also beneficial in non-intubated patients with cerebral malaria in resource poor settings. We hypothesized that the risk of aspiration pneumonia might outweigh the potential benefits of earlier recovery and prevention of hypoglycaemia. Method and Findings A randomized trial of early (day of admission) versus late (after 60 hours in adults or 36 hours in children) start of enteral feeding was undertaken in patients with cerebral malaria in Chittagong, Bangladesh from May 2008 to August 2009. The primary outcome measures were incidence of aspiration pneumonia, hypoglycaemia and coma recovery time. The trial was terminated after inclusion of 56 patients because of a high incidence of aspiration pneumonia in the early feeding group (9/27 (33%)), compared to the late feeding group (0/29 (0%)), p = 0.001). One patient in the late feeding group, and none in the early group, had hypoglycaemia during admission. There was no significant difference in overall mortality (9/27 (33%) vs 6/29 (21%), p = 0.370), but mortality was 5/9 (56%) in patients with aspiration pneumonia. Conclusions In conclusion, early start of enteral feeding is detrimental in non-intubated patients with cerebral malaria in many resource-poor settings. Evidence gathered in resource rich settings is not necessarily transferable to resource-poor settings. Trial Registration Controlled-Trials.com ISRCTN57488577

Cost-effectiveness of artesunate for the treatment of severe malaria

Objective  To explore the cost‐effectiveness of artesunate against quinine based principally on the findings of a large multi‐centre trial carried out in Southeast Asia.

Malarial Retinopathy in Bangladeshi Adults

To establish if assessment of malarial retinopathy in adult malaria using ophthalmoscopy by non-ophthalmologists has clinical and prognostic significance, 210 Bangladeshi adults were assessed by both direct and indirect ophthalmoscopy; 20 of 20 healthy subjects and 20 of 20 patients with vivax malaria showed no retinal changes, whereas in patients with falciparum malaria, indirect ophthalmoscopy revealed malarial retinopathy (predominantly retinal hemorrhages) in 18 of 21 (86%) fatal, 31 of 75 (41%) cerebral, 16 of 64 (25%) non-cerebral but severe, and 1 of 31 (3%) uncomplicated cases. Direct ophthalmoscopy missed retinopathy in one of these cases and found fewer retinal hemorrhages (mean difference = 3.09; 95% confidence interval = 1.50–4.68; P < 0.0001). Severity of retinopathy increased with severity of disease (P for trend < 0.0001), and renal failure, acidosis, and moderate/severe retinopathy were independent predictors of mortality by both ophthalmoscopic techniques. Direct ophthalmoscopy by non-ophthalmologists is an important clinical tool to aid diagnosis and prognosis in adults with severe malaria, and indirect ophthalmoscopy by non-ophthalmologists, although more sensitive, provides minimal additional prognostic information.

Laboratory prediction of the requirement for renal replacement in acute falciparum malaria

BackgroundAcute renal failure is a common complication of severe malaria in adults, and without renal replacement therapy (RRT), it carries a poor prognosis. Even when RRT is available, delaying its initiation may increase mortality. Earlier identification of patients who will need RRT may improve outcomes.MethodProspectively collected data from two intervention studies in adults with severe malaria were analysed focusing on laboratory features on presentation and their association with a later requirement for RRT. In particular, laboratory indices of acute tubular necrosis (ATN) and acute kidney injury (AKI) that are used in other settings were examined.ResultsData from 163 patients were available for analysis. Whether or not the patients should have received RRT (a retrospective assessment determined by three independent reviewers) was used as the reference. Forty-three (26.4%) patients met criteria for dialysis, but only 19 (44.2%) were able to receive this intervention due to the limited availability of RRT. Patients with impaired renal function on admission (creatinine clearance < 60 ml/min) (n = 84) had their laboratory indices of ATN/AKI analysed. The plasma creatinine level had the greatest area under the ROC curve (AUC): 0.83 (95% confidence interval 0.74-0.92), significantly better than the AUCs for, urinary sodium level, the urea to creatinine ratio (UCR), the fractional excretion of urea (FeUN) and the urinary neutrophil gelatinase-associated lipocalcin (NGAL) level. The AUC for plasma creatinine was also greater than the AUC for blood urea nitrogen level, the fractional excretion of sodium (FeNa), the renal failure index (RFI), the urinary osmolality, the urine to plasma creatinine ratio (UPCR) and the creatinine clearance, although the difference for these variables did not reach statistical significance.ConclusionsIn adult patients with severe malaria and impaired renal function on admission, none of the evaluated laboratory indices was superior to the plasma creatinine level when used to predict a later requirement for renal replacement therapy.

Host immunity to Plasmodium falciparum and the assessment of emerging artemisinin resistance in a multinational cohort

Significance Slow-clearing artemisinin-resistant malaria parasites are now well established in the Greater Mekong Subregion. This large multinational therapy efficacy study incorporating clinical data, molecular drug-resistance markers, and immune profiling aimed to understand how variations in population levels of naturally acquired malarial immunity affect the slow-clearing phenotype, emergence of artemisinin resistance-associated mutations, and assessment of the geographical spread of artemisinin resistance. We found that slow-clearing mutant parasites occur at higher frequencies in areas where immunity is lowest, patients with higher immunity have faster clearance times, and immunity has the greatest effect on clearance in patients with slow-clearing mutant parasites. Immunity plays an important role in the emergence of resistant parasites and can confound the World Health Organization’s phenotype and genotype definitions of artemisinin resistance. Artemisinin-resistant falciparum malaria, defined by a slow-clearance phenotype and the presence of kelch13 mutants, has emerged in the Greater Mekong Subregion. Naturally acquired immunity to malaria clears parasites independent of antimalarial drugs. We hypothesized that between- and within-population variations in host immunity influence parasite clearance after artemisinin treatment and the interpretation of emerging artemisinin resistance. Antibodies specific to 12 Plasmodium falciparum sporozoite and blood-stage antigens were determined in 959 patients (from 11 sites in Southeast Asia) participating in a multinational cohort study assessing parasite clearance half-life (PCt1/2) after artesunate treatment and kelch13 mutations. Linear mixed-effects modeling of pooled individual patient data assessed the association between antibody responses and PCt1/2. P. falciparum antibodies were lowest in areas where the prevalence of kelch13 mutations and slow PCt1/2 were highest [Spearman ρ = −0.90 (95% confidence interval, −0.97, −0.65), and Spearman ρ = −0.94 (95% confidence interval, −0.98, −0.77), respectively]. P. falciparum antibodies were associated with faster PCt1/2 (mean difference in PCt1/2 according to seropositivity, −0.16 to −0.65 h, depending on antigen); antibodies have a greater effect on the clearance of kelch13 mutant compared with wild-type parasites (mean difference in PCt1/2 according to seropositivity, −0.22 to −0.61 h faster in kelch13 mutants compared with wild-type parasites). Naturally acquired immunity accelerates the clearance of artemisinin-resistant parasites in patients with falciparum malaria and may confound the current working definition of artemisinin resistance. Immunity may also play an important role in the emergence and transmission potential of artemisinin-resistant parasites.