Molecular markers associated with the increase of chloroquine resistance and disease severity in Plasmodium vivax are needed. The objective of this study was to evaluate the expression levels of pvcrt-o and pvmdr-1 genes in a group of patients presenting CQRPv and patients who developed severe complications triggered exclusively by P. vivax infection. Two different sets of patients were included to this comprehensive study performed in the Brazilian Amazon: 1) patients with clinically characterized chloroquine-resistant P. vivax compared with patients with susceptible parasites from in vivo studies and 2) patients with severe vivax malaria compared with patients without severity. Quantitative real-time PCR was performed to compare the transcript levels of two main transporters genes, P. vivax chloroquine resistance transporter (pvcrt-o) and the P. vivax multidrug resistance transporter (pvmdr-1). Twelve chloroquine resistant cases and other 15 isolates from susceptible cases were included in the first set of patients. For the second set, seven patients with P. vivax-attributed severe and 10 mild manifestations were included. Parasites from patients with chloroquine resistance presented up to 6.1 (95% CI: 3.8–14.3) and 2.4 (95% CI: 0.53–9.1) fold increase in pvcrt-o and pvmdr-1 expression levels, respectively, compared to the susceptible group. Parasites from the severe vivax group had a 2.9 (95% CI: 1.1–8.3) and 4.9 (95% CI: 2.3–18.8) fold increase in pvcrt-o and pvmdr-1 expression levels as compared to the control group with mild disease. These findings suggest that chloroquine resistance and clinical severity in P. vivax infections are strongly associated with increased expression levels of the pvcrt-o and pvmdr-1 genes likely involved in chloroquine resistance.

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SummaryIn the Brazilian Amazon, the artesunate–amodiaquine combination was more effective in preventing Plasmodium vivax recurrence. With a favorable safety profile, this antimalarial treatment proved to be a good first-line alternative. Chloroquine resistance is probably underestimated in the area.

Snakebite envenoming (SBE) is a neglected tropical disease with significant global morbidity and mortality. Even when antivenom is available in low-resource areas, health workers do not receive adequate training to manage SBEs. This study aims to develop and validate a clinical practice guideline (CPG) for SBE management across Brazil. A panel of expert judges with academic and/or technical expertise in SBE management performed content validation. The content validity index (CVI) score was 90% for CPG objectives, 89% for structure and presentation and 92% for relevance and classified the CPG as valid. A semantic validation was performed by analyzing focus group discussions with doctors and nurses from three municipalities of the Brazilian Amazon, after a 5-day meeting during which the CPG was presented. Two central themes emerged: knowledge acquired during the meeting and recommendations for improving the CPG. Based on these results, the CPG was revised into a final version. This study presents the successful development and validation process of a CPG for SBE management, which is targeted to a specific low-resource, high-burden setting. This development and validation process can be adapted to other settings and/or other neglected tropical diseases.