RESUMEN
Background: Difficulties associated with the assessment of glucose-6-phosphate dehydrogenase deficiency (G6PDd), particularly in remote areas, hinders the safe use of 8-aminoquinolines such as primaquine (PQ) and tafenoquine against Plasmodium vivax malaria due to the risk of haemolysis. Methods: This cross-sectional study was conducted in 41 malaria-endemic municipalities of six states in the Brazilian Amazon, between 2014 and 2018. Male individuals were screened for G6PDd using the qualitative Fluorescent Spot Test using fingerpick-collected whole blood samples. Point and interval estimates of the G6PDd prevalence were calculated for each state. Deficient samples were genotyped for the most prevalent variants in the Amazon. Frequencies of P. vivax malaria recurrences were estimated for G6PDd and non-G6PDd patients. Interpretation: This is one of the largest surveys ever conducted in Latin America, covering the entire malaria endemic area in the Brazilian Amazon. These results indicate that an important proportion of the population is at risk of hemolysis if exposed to PQ and its congener drug tafenoquine. The adoption of G6PDd screening protocols is essential to ensure the safety of individuals treated with those drugs and should also be considered when implementing malaria elimination strategies. Findings: A total of 14,847 individuals were included, of which 5.6% presented G6PDd. The state of Acre had the highest G6PDd prevalence (8.3%), followed by Amapá (5.8%), Pará (5.7%), Rondônia (5.4%), Roraima (4.2%) and Amazonas (4.0%). From 828 genotyped samples, African A+ (6.2%), African A- (39.3%) and wild-type (non-African non-Mediterranean; 54.2%) variants were found. A greater proportion of malaria recurrences was found among G6PD deficient individuals [16.7% vs 4.1%, Risk ratio 3.52 (2.16-5.74) p < 0.01]. Funding: Brazilian Ministry of Health; Fundação de Amparo à Pesquisa do Estado do Amazonas (FAPEAM).