SummaryBackgroundChloroquine remains the mainstay of treatment for Plasmodium vivax malaria despite increasing reports of treatment failure. We did a systematic review and meta-analysis to investigate the effect of chloroquine dose and the addition of primaquine on the risk of recurrent vivax malaria across different settings.MethodsA systematic review done in MEDLINE, Web of Science, Embase, and Cochrane Database of Systematic Reviews identified P vivax clinical trials published between Jan 1, 2000, and March 22, 2017. Principal investigators were invited to share individual patient data, which were pooled using standardised methods. Cox regression analyses with random effects for study site were used to investigate the roles of chloroquine dose and primaquine use on rate of recurrence between day 7 and day 42 (primary outcome). The review protocol is registered in PROSPERO, number CRD42016053310.FindingsOf 134 identified chloroquine studies, 37 studies (from 17 countries) and 5240 patients were included. 2990 patients were treated with chloroquine alone, of whom 1041 (34·8%) received a dose below the target 25 mg/kg. The risk of recurrence was 32·4% (95% CI 29·8–35·1) by day 42. After controlling for confounders, a 5 mg/kg higher chloroquine dose reduced the rate of recurrence overall (adjusted hazard ratio [AHR] 0·82, 95% CI 0·69–0·97; p=0·021) and in children younger than 5 years (0·59, 0·41–0·86; p=0·0058). Adding primaquine reduced the risk of recurrence to 4·9% (95% CI 3·1–7·7) by day 42, which is lower than with chloroquine alone (AHR 0·10, 0·05–0·17; p<0·0001).InterpretationChloroquine is commonly under-dosed in the treatment of vivax malaria. Increasing the recommended dose to 30 mg/kg in children younger than 5 years could reduce substantially the risk of early recurrence when primaquine is not given. Radical cure with primaquine was highly effective in preventing early recurrence and may also improve blood schizontocidal efficacy against chloroquine-resistant P vivax.FundingWellcome Trust, Australian National Health and Medical Research Council, and Bill & Melinda Gates Foundation.

Data on chloroquine (CQ)-resistant Plasmodium vivax in LatinAmerica is limited, even with the current research efforts to sustain an efficient malaria control program in all these countries where P. vivax is endemic and where malaria still is a major public health issue. This study estimated in vivo CQ resistance in patients with uncomplicated P. vivax malaria, with use of CQ and primaquine simultaneously, in the Brazilian Amazon. Of a total of 135 enrolled subjects who accomplished the 28-day follow-up, parasitological failure was observed in 7 (5.2%) patients, in whom plasma CQ and desethylchloroquine (DCQ) concentrations were above 100 ng/dl. Univariate analysis showed that previous exposure to malaria and a higher initial mean parasitemia were associated with resistance but not with age or gender. In the multivariate analysis, only high initial parasitemia remained significant. Hemoglobin levels were similar at the beginning of the follow-up and were not associated with parasitemia. However, at day 3 and day 7, hemoglobin levels were significantly lower in patients presenting CQ resistance. The P. vivax dhfr (pvdhfr), pvmrp1, pvmdr1, and pvdhps gene mutations were not related to resistance in this small sample. P. vivax CQ resistance is already a problem in the Brazilian Amazon, which could be to some extent associated with the simultaneous report of anemia triggered by this parasite, a common complication of the disease in most of the areas of endemicity.

(−)-β-caryophyllene (BCP), a cannabinoid receptor type 2 (CB2)-selective phytocannabinoid, has already been shown in precedent literature to exhibit both anti-inflammatory and analgesic effects in mouse models of inflammatory and neuropathic pain. Herein, we endeavored to investigate the therapeutic potential of BCP on experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS). Furthermore, we sought to demonstrate some of the mechanisms that underlie the modulation BCP exerts on autoimmune activated T cells, the pro-inflammatory scenery of the central nervous system (CNS), and demyelination. Our findings demonstrate that BCP significantly ameliorates both the clinical and pathological parameters of EAE. In addition, data hereby presented indicates that mechanisms underlying BCP immunomodulatory effect seems to be linked to its ability to inhibit microglial cells, CD4+ and CD8+ T lymphocytes, as well as protein expression of pro-inflammatory cytokines. Furthermore, it diminished axonal demyelination and modulated Th1/Treg immune balance through the activation of CB2 receptor. Altogether, our study represents significant implications for clinical research and strongly supports the effectiveness of BCP as a novel molecule to target in the development of effective therapeutic agents for MS.

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BackgroundThe relation between therapeutic failure and non-adherence to treatment of malaria has been clearly established. Several measures have been used to estimate adherence to Plasmodium vivax therapy, but few protocols have been validated to ensure reliability of the estimates of adherence. The objective of this study was to validate a five-item-reported-questionnaire derived from original Morisky four-item scale to estimate adherence to P. vivax malaria therapy.MethodsA five-item-reported questionnaire was applied to patients after treatment of P. vivax malaria, considering behaviours regarding to forgetfulness, carelessness as to time of administration, cessation or discontinuation of use and replication of dose. Data were collected in dichotomous and Likert scales. Reliability was assessed by Cronbach’s alpha and by the contribution of each item to total. The concurrent validation was done with pill count and concordance between measures of adherence by coefficient of Kappa. Sensitivity, specificity and accuracy were also determined.ResultsA total of 135 patients were enrolled in the study. Adherence ranged from 63.8 to 72.7% in both psychometric measures and pill count. The responses on the Likert scale showed higher proportion of non-adherence behaviour, greater variance and concordance with pill count, as well as more sensitive to characterize the behaviour of self-medication. The internal consistency of questionnaire was moderate. Significant correlations were seen with items regarding the forgiveness or careless in taking pills in all scales. The agreement between psychometric measures and pill count was considered satisfactory. The non-adherence to malaria therapy in an endemic area of Amazon basin was 33.3%.ConclusionThe five-item-reported questionnaire with responses on Likert scale is a feasible option for reliable estimation of adherence to malaria therapy in endemic areas.

Background Malaria causes a reduction in haemoglobin that is compounded by primaquine, particularly in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. The aim of this study was to determine the relative contributions to red cell loss of malaria and primaquine in patients with uncomplicated Plasmodium vivax . Methods A systematic review identified P. vivax efficacy studies of chloroquine with or without primaquine published between January 2000 and March 2017. Individual patient data were pooled using standardised methodology, and the haematological response versus time was quantified using a multivariable linear mixed effects model with non-linear terms for time. Mean differences in haemoglobin between treatment groups at day of nadir and day 42 were estimated from this model. Results In total, 3421 patients from 29 studies were included: 1692 (49.5%) with normal G6PD status, 1701 (49.7%) with unknown status and 28 (0.8%) deficient or borderline individuals. Of 1975 patients treated with chloroquine alone, the mean haemoglobin fell from 12.22 g/dL [95% CI 11.93, 12.50] on day 0 to a nadir of 11.64 g/dL [11.36, 11.93] on day 2, before rising to 12.88 g/dL [12.60, 13.17] on day 42. In comparison to chloroquine alone, the mean haemoglobin in 1446 patients treated with chloroquine plus primaquine was − 0.13 g/dL [− 0.27, 0.01] lower at day of nadir ( p = 0.072), but 0.49 g/dL [0.28, 0.69] higher by day 42 ( p < 0.001). On day 42, patients with recurrent parasitaemia had a mean haemoglobin concentration − 0.72 g/dL [− 0.90, − 0.54] lower than patients without recurrence ( p < 0.001). Seven days after starting primaquine, G6PD normal patients had a 0.3% (1/389) risk of clinically significant haemolysis (fall in haemoglobin > 25% to < 7 g/dL) and a 1% (4/389) risk of a fall in haemoglobin > 5 g/dL. Conclusions Primaquine has the potential to reduce malaria-related anaemia at day 42 and beyond by preventing recurrent parasitaemia. Its widespread implementation will require accurate diagnosis of G6PD deficiency to reduce the risk of drug-induced haemolysis in vulnerable individuals. Trial registration This trial was registered with PROSPERO: CRD42016053312 . The date of the first registration was 23 December 2016. Electronic supplementary material The online version of this article (10.1186/s12916-019-1386-6) contains supplementary material, which is available to authorized users.

BackgroundThe resistance of Plasmodium vivax to chloroquine has become an obstacle to control strategies based on the use of anti-malarials. The current study investigated the association between P. vivax CQ-resistance in vivo with copy number variation and mutations in the promoter region in pvcrt-o and pvmdr1 genes.MethodsThe study included patients with P. vivax that received supervised treatment with chloroquine and primaquine. Recurrences were actively recorded during this period.ResultsAmong the 60 patients with P. vivax, 25 were CQ-resistant and 35 CQ-susceptible. A frequency of 7.1% of multi-copy pvcrt-o was observed in CQ-susceptible samples and 7.7% in CQ-resistant at D0 (P > 0.05) and 33.3% in CQ-resistant at DR (P < 0.05). For pvmdr1, 10.7% of the CQ-susceptible samples presented multiple copies compared to 11.1% in CQ-resistant at D0 and 0.0% in CQ-resistant at DR (P > 0.05). A deletion of 19 bp was found in 11/23 (47.6%) of the patients with CQ-susceptible P. vivax and 3/10 (23.1%) of the samples with in CQRPv at D0. At day DR, 55.5% of the samples with CQRPv had the 19 bp deletion. For the pvmdr-1 gene, was no variation in the analysed gene compared to the P. vivax reference Sal-1.ConclusionsThis was the first study with 42-day clinical follow-up to evaluate the variation of the number of copies and polymorphisms in the promoter region of the pvcrt-o and pvmdr1 genes in relation to treatment outcomes. Significantly higher frequency of multi-copy pvcrt-o was found in CQRPv samples at DR compared to CQ-susceptible, indicating parasite selection of this genotype after CQ treatment and its association with CQ-resistance in vivo.Electronic supplementary materialThe online version of this article (10.1186/s12936-018-2411-5) contains supplementary material, which is available to authorized users.

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