Efficacy of chloroquine and primaquine for the treatment of uncomplicated plasmodium vivax malaria in Cruzeiro do Sul, Brazil

Acre State Health Secretariat. Acre, AC, Brazil.Acre State Health Secretariat. Acre, AC, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Centers for Disease Control and Prevention. Center for Global Health. Division of Parasitic Diseases and Malaria. Malaria Branch. Atlanta, GA, USA / Atlanta Research and Education Foundation. Decatur, GA, USA.Centers for Disease Control and Prevention. Center for Global Health. Division of Parasitic Diseases and Malaria. Malaria Branch. Atlanta, GA, USAAcre State Health Secretariat. Acre, AC, Brazil.Brazilian Ministry of Health. National Malaria Control Program. Brasilia, DF, Brazil.Centers for Disease Control and Prevention. Center for Global Health. Division of Parasitic Diseases and Malaria. Malaria Branch. Atlanta, GA, USAMinistério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Brazilian Ministry of Health. National Malaria Control Program. Brasilia, DF, Brazil.Centers for Disease Control and Prevention. Center for Global Health. Division of Parasitic Diseases and Malaria. Malaria Branch. Atlanta, GA, USA.We evaluated the efficacy of chloroquine and primaquine on uncomplicated Plasmodium vivax malaria in Cruzeiro do Sul, Brazil, in 2014. Patients ≥ 5 years of age with either fever or history of fever, and laboratoryconfirmed P. vivax monoinfection received chloroquine (total dose = 25 mg/kg) and primaquine (total dose = 3.5 mg/kg), and were followed up for 168 days (24 weeks). We used microsatellite genotyping to differentiate recurrent infections caused by heterologous parasites from those caused by homologous ones. No new P. vivax episode occurred by Day 28 among 119 enrolled patients, leading to Day 28, with adequate clinical and parasitological response (ACPR) of 100% (95% confidence interval [CI] = 96.7–100%). Twenty-eight P. vivax episodes occurred by Day 168, with uncorrected ACPR of 69.9% (95% CI = 59.5–79.0%). Fifteen of these episodes were caused by either homologous haplotypes or haplotypes that could not be determined. Excluding the 13 recurrent episodes caused by heterologous parasites, Day 168 microsatellite-corrected ACPR was estimated at 81.2% (95% CI = 71.0–89.1%). Chloroquine and primaquine remain efficacious to treat acute uncomplicated P. vivax infection, but moderate recurrence rates were observed within 24 weeks of follow-up