Efficacy of 3 Regimens of Chloroquine and Primaquine for Treatment of P. Vivax Malaria, Cruzeiro do Sul, Acre, Brazil

We plan to assess the efficacy of 3 different regimens of chloroquine and primaquine for the treatment of P. vivax infections in Cruzeiro do Sul, Acre, Brazil. Patients will be divided in 3 different groups: treatment with regular dose of primaquine (0.5 mg/kg per day for 7 days) with directly observed therapy; regular dose of primaquine without directly observed therapy; and increased total dose of primaquine (0.5 mg/kg per day for14 days) with directly observed therapy. All patients will receive chloroquine (CQ) for three days at a daily dose of approximately 25 mg/Kg in accordance with the Brazilian National Malaria Control guidelines. Clinical and parasitologic parameters will be monitored over a 28-day follow-up period to evaluate drug efficacy and for a total period of 168 days (24 weeks) to evaluate chances of recrudescence, relapse, or reinfection. Results from this drug efficacy study will be used to assist the Brazilian Ministry of Health in assessing their national malaria treatment policy for P. vivax malaria.

Background: The World Health Organization recommends that antimalarial treatment policies be evaluated every few years to check their efficacy. P. vivax malaria is the most common species in Brazil and cases are concentrated in the Amazon Region in Brazil. Objectives: Assess the efficacy of 3 different regimens of chloroquine and primaquine for the treatment of P. vivax infections in Cruzeiro do Sul, Acre, Brazil. Methods: An in vivo drug efficacy study will be conducted in Cruzeiro do Sul, Acre State, Brazil. A total of 257 study participants ≥5 years of age with parasitologically confirmed P. vivax monoinfections will be included. Patients will be divided in 3 different groups: treatment with regular dose of primaquine (0.5 mg/kg per day for 7 days) with directly observed therapy; regular dose of primaquine without directly observed therapy; and increased total dose of primaquine (0.5 mg/kg per day for14 days) with directly observed therapy. All patients will receive chloroquine (CQ) for three days at a daily dose of approximately 25 mg/Kg in accordance with the Brazilian National Malaria Control guidelines. Primaquine will be given for 7 or 14 days under supervision or not, depending on the study group. Clinical and parasitologic parameters will be monitored over a 28-day follow-up period to evaluate drug efficacy and for a total period of 168 days (24 weeks) to evaluate chances of recrudescence, relapse, or reinfection. Blood samples will be taken to measure the CQ levels in blood on Day 7 and day of failure, if occurring in the initial 28 days of follow up. In addition, a blood sample will be collected on filter paper on first day and on day of suspected failure to help differentiate parasite genotypes using techniques based on polymerase chain reaction. Results from this drug efficacy study will be used to assist the Brazilian Ministry of Health in assessing their national malaria treatment policy for P. vivax malaria.