METHODS: In a systematic study of the presentation and course of patients with acute P. knowlesi infection, clinical and laboratory data were collected from previously untreated, nonpregnant adults admitted to the hospital with polymerase chain reaction-confirmed acute malaria at Kapit Hospital (Sarawak, Malaysia) from July 2006 through February 2008.
RESULTS: Of 152 patients recruited, 107 (70%) had P. knowlesi infection, 24 (16%) had Plasmodium falciparum infection, and 21 (14%) had Plasmodium vivax. Patients with P. knowlesi infection presented with a nonspecific febrile illness, had a baseline median parasitemia value at hospital admission of 1387 parasites/microL (interquartile range, 6-222,570 parasites/microL), and all were thrombocytopenic at hospital admission or on the following day. Most (93.5%) of the patients with P. knowlesi infection had uncomplicated malaria that responded to chloroquine and primaquine treatment. Based on World Health Organization criteria for falciparum malaria, 7 patients with P. knowlesi infection (6.5%) had severe infections at hospital admission. The most frequent complication was respiratory distress, which was present at hospital admission in 4 patients and developed after admission in an additional 3 patients. P. knowlesi parasitemia at hospital admission was an independent determinant of respiratory distress, as were serum creatinine level, serum bilirubin, and platelet count at admission (p < .002 for each). Two patients with knowlesi malaria died, representing a case fatality rate of 1.8% (95% confidence interval, 0.2%-6.6%).
CONCLUSIONS: Knowlesi malaria causes a wide spectrum of disease. Most cases are uncomplicated and respond promptly to treatment, but approximately 1 in 10 patients develop potentially fatal complications.
AIM OF THE STUDY: The aim of the current study is to evaluate the traditionally used medicinal plants for in vitro anti-malarial activity against human malaria parasite Plasmodium falciparum and profiling secondary metabolite using spectroscopic and chromatographic methods. Chemical profiling of active secondary metabolites in the extracts was undertaken using LC-MS.
MATERIALS AND METHODS: Based on the ethno-botanical data V. negundo L. was selected for in vitro anti-malarial activity against P. falciparum chloroquine-sensitive (3D7) and multidrug resistant (K1) strains using SYBR Green-I based fluorescence assay. Cytotoxicity of extracts was evaluated in VERO cell line using the MTT assay. Haemolysis assay was performed using human red blood cells. Secondary metabolites profiling was undertaken using chromatographic and spectroscopic analysis. Liquid chromatography analysis was performed using a C18, 150 X 2.1, 2.6 μm column with gradient mobile phase Solvent A: 95% (H2O: ACN), Solvent B: Acetonitrile, Solvent C: Methanol, Solvent D: 5 mM NH4 in 95:5 (H2O: ACN) at a constant flow rate of 0.250 ml/min. The LC-MS spectra were acquired in both positive and negative ion modes with electrospray ionization (ESI) source.
RESULTS: The anti-malarial active extract of V. negundo L. leaf exhibited potent anti-malarial activity with IC50 values of 7.21 μg/ml and 7.43 μg/ml against 3D7 and K1 strains, respectively with no evidence of significant cytotoxicity against mammalian cell line (VERO) and no toxicity as observed in haemolysis assay. The HPLC-LC-MS analysis of the extract led to identification of 73 compounds. We report for the first time the presence of Sabinene hydrate acetate, 5-Hydroxyoxindole, 2(3,4-dimethoxyphenyl)-6, 7-dimethoxychromen-4-one, Cyclotetracosa-1, 13-diene and 5, 7-Dimethoxyflavanone in the anti-malarial active extract of V. negundo L. leaf. Agnuside, Behenic acid and Globulol are some of the novel compounds with no reports of anti-malarial activity so far and require further evaluation in pure form for the development of potent anti-malarial compounds.
CONCLUSIONS: The result report and scientifically validate the traditional use of V. negundo L. for the treatment of malaria providing new avenues for anti-malarial drug development. Several novel and unknown compounds were identified that need to be further characterized for anti-malarial potential.
METHODS: We did this open-label, randomised controlled trial at three district hospitals in Sabah, Malaysia. Patients aged 1 year or older with uncomplicated P knowlesi malaria were randomly assigned, via computer-generated block randomisation (block sizes of 20), to receive oral artesunate-mefloquine (target dose 12 mg/kg artesunate and 25 mg/kg mefloquine) or chloroquine (target dose 25 mg/kg). Research nursing staff were aware of group allocation, but allocation was concealed from the microscopists responsible for determination of the primary endpoint, and study participants were not aware of drug allocation. The primary endpoint was parasite clearance at 24 h. Analysis was by modified intention to treat. This study is registered with ClinicalTrials.gov, number NCT01708876.
FINDINGS: Between Oct 16, 2012, and Dec 13, 2014, we randomly assigned 252 patients to receive either artesunate-mefloquine (n=127) or chloroquine (n=125); 226 (90%) patients comprised the modified intention-to-treat population. 24 h after treatment, we recorded parasite clearance in 97 (84% [95% CI 76-91]) of 115 patients in the artesunate-mefloquine group versus 61 (55% [45-64]) of 111 patients in the chloroquine group (difference in proportion 29% [95% CI 18·0-40·8]; p<0·0001). Parasite clearance was faster in patients given artesunate-mefloquine than in those given chloroquine (18·0 h [range 6·0-48·0] vs 24·0 h [6·0-60·0]; p<0·0001), with faster clearance of ring stages in the artesunate-mefloquine group (mean time to 50% clearance of baseline parasites 8·6 h [95% CI 7·9-9·4] vs 13·8 h [12·1-15·4]; p<0·0001). Risk of anaemia within 28 days was lower in patients in the artesunate-mefloquine group (71 [62%; 95% CI 52·2-70·6]) than in those in the chloroquine group (83 [75%; 65·6-82·5]; p=0·035). Gametocytaemia as detected by PCR for pks25 was present in 44 (86%) of 51 patients in the artesunate-mefloquine group and 41 (84%) of 49 patients in the chloroquine group at baseline, and in three (6%) of 49 patients and two (4%) of 48 patients, respectively, at day 7. Fever clearance was faster in the artesunate-mefloquine group (mean 11·5 h [95% CI 8·3-14·6]) than in the chloroquine group (14·8 h [11·7-17·8]; p=0·034). Bed occupancy was 2426 days per 1000 patients in the artesunate-mefloquine group versus 2828 days per 1000 patients in the chloroquine group (incidence rate ratio 0·858 [95% CI 0·812-0·906]; p<0·0001). One (<1%) patient in the artesunate-mefloquine group had a serious neuropsychiatric event regarded as probably related to study drug.
INTERPRETATION: Artesunate-mefloquine is highly efficacious for treatment of uncomplicated P knowlesi malaria. The rapid therapeutic response of the drug offers significant advantages compared with chloroquine monotherapy and supports a unified treatment policy for artemisinin-based combination therapy for all Plasmodium species in co-endemic areas.
FUNDING: Malaysian Ministry of Health, Australian National Health and Medical Research Council, and Asia Pacific Malaria Elimination Network.