Efficacy in the treatment of malaria by Plasmodium vivax in Oiapoque, Brazil, on the border with French Guiana: the importance of control over external factors

Abstract

BackgroundPlasmodium vivax malaria is an important public health issue in the Amazon region, and it accounts for approximately 84 % of cases of the disease. Migration across the border between Brazil and French Guiana contributes to the maintenance of the disease. The aim of this study was to evaluate the therapeutic and parasitological responses of patients with P. vivax malaria treated with chloroquine and primaquine in the socio-environmental context of cross-border interactions between Brazil and French Guiana. The factors controlled were diagnostic agreement, adherence, adjustment of primaquine doses for patient weight, and quality of the drugs used. MethodsA prospective study was conducted in 2011 with 103 individuals aged 10–60 years with a positive diagnosis of P. vivax treated with chloroquine (10 mg base/kg on the first day, followed by 7.5 mg/kg on the second and third days) and primaquine for 7 days, who were followed for 28 days. The primaquine doses were adjusted for the patients’ weight. A number of factors were determined: epidemiological characteristics, origin of patients, signs and symptoms, initial parasitaemia and parasitaemia clearance time, blood concentrations of chloroquine and primaquine, quality of anti-malarial drugs and diagnostic agreement.ResultsNinety-five patients were followed for 28 days. There was a 100 % agreement in microscopic diagnosis between field laboratory and reference centre. The adhesion to the treatment was 100 %. Of these patients, 32.6 % received a weight-adjusted dose of primaquine. The chloroquine and primaquine tablets were consistent with the optimal quality limits for human consumption. The investigated patients achieved optimal blood exposure to anti-malarial drugs. The parasitological and therapeutic response was adequate in 99.0 % of cases.ConclusionsIn the municipality of Oiapoque, the therapeutic regime used for the treatment of P. vivax malaria using chloroquine combined with primaquine remains effective, when external factors are controlled, such as the quality of anti-malarial drugs, the adhesion to the treatment prescribed, the correct diagnostic and the adjustment of primaquine dose for patient body weight.

Safety, efficacy and pharmacokinetic evaluations of a new coated chloroquine tablet in a single-arm open-label non-comparative trial in Brazil: a step towards a user-friendly malaria vivax treatment

“…The efficacy results reported here are comparable to other recent publications in Brazil [ 30 ]. Although the efficacy was adequate at 28 days, as recommended by the WHO [ 23 ], this follow-up period may not provide the best sensitivity for evaluating vivax relapse in the clinical trial in Brazil.…”

Pharmacotherapy follow-up: Role in active malaria surveillance in a travel medicine centre outside the transmission area in Brazil

“…Therapeutic monitoring studies on artemisinin derivatives for P. falciparum treatment in Africa demonstrated therapeutic success higher than 95% . Similar high treatment success was reported in therapeutic efficacy studies for vivax malaria with chloroquine and primaquine in the African continent and in Brazil . Despite differences in study design, therapeutic success rates were similar in this and previous studies, underscoring the importance of pharmacotherapy follow‐up of patients with malaria.…”

Levels of primaquine and carboxyprimaquine in patients with malaria vivax from the Brazilian Amazon basin

“…The sample size was based on previous studies of efficacy conducted in this endemic setting, which has reported a failure rate of about 2% to the standard treatment of malaria vivax , with a confidence level of 95% and precision of 5%. Thus, a minimum sample of 30 patients was required for the study 2 , 7 , 15 , 16 .…”