Efficacy and Safety of Artesunate + Amodiaquine With SLD of Primaquine for Treatment of Falciparum Malaria in Zanzibar

Overview

The general objective of this study is to assess the therapeutic efficacy and safety of artesunate + amodiaquine combined with a single low dose of primaquine (0.25 mg/kg) for the treatment of uncomplicated P. falciparum malaria patients in Zanzibar. The specific objectives are: * To determine the clinical and parasitological efficacy of artesunate + amodiaquine and primaquine in the treatment of uncomplicated Plasmodium falciparum infection. * To differentiate recurrent infections during follow-up, i.e. recrudescence from new infections, by polymerase chain reaction (PCR). * To evaluate the incidence of adverse events, particularly with regards to potential hematological adverse events of primaquine. * To determine the polymorphism of molecular markers associated with artesunate + amodiaquine tolerance/resistance. * To formulate recommendations, which will enable the Zanzibar Ministry of Health to make informed decisions about whether the current national antimalarial treatment guidelines should be updated or not. * To determine efficacy rate of the first line treatment compared to the first efficacy trial thirteen years ago.

The aim of this study is to provide policymakers with updated efficacy and safety data of artesunate + amodiaquine in combination with a single low dose of primaquine (0.25 mg/kg) and data on genetic markers of tolerance/resistance to artemisinin based combination therapies (ACTs), proposed as an early warning system for development and spread of antimalarial drug resistance, in Zanzibar. The study protocol is based on the new WHO guidelines for surveillance of antimalarial drug efficacy (WHO 2014). This surveillance study was designed as a one-arm prospective evaluation of the clinical and parasitological responses to directly observed treatment for uncomplicated malaria. Participants were recruited from febrile patients, i.e. documented axillary temperature ≥37.5 °C or history of fever during the past 48 hours, of 3 months and older, presenting at primary health care facilities in Zanzibar, with microscopy confirmed uncomplicated P. falciparum infection. Enrolled patients received directly observed treatment with artesunate + amodiaquine once daily for 3 consecutive days according to the national malaria treatment guidelines. A single low dose of primaquine (0.25 mg/kg) was administered together with the first artesunate + amodiaquine dose. Clinical and parasitological as well as safety parameters were monitored over a 28-day follow-up period. The follow-up consisted of a fixed schedule of check-up visits and corresponding clinical and laboratory examinations. On the basis of the results of these assessments, the patients were classified as having therapeutic failure (early or late) or an adequate response. Blood samples from patients experiencing therapeutic failure during the follow-up period were used to estimate the efficacy of the study drugs based on PCR analysis to distinguish between recrudescence (treatment failures) and reinfection (new infections). A standard physical examination was performed at baseline (day 0 before drug administration) and on days 1, 2, 3, 7, 14, 21, and 28 ,or any other day if the patient returned spontaneously and parasitological reassessment was required. This examination included measuring axillary temperature, with a thermometer that has a precision of 0.1 °C, as well as conducting a thick film for asexual and gametocyte counts and species identification. Haemoglobin was assessed systematically on all participants on days 0, 3, 7, 14 and 28 using Hemocue, and at any time in case of clinical suspicion of anaemia, i.e. pallor, according to standard case management of malaria in Zanzibar. In order to differentiate a recrudescence (treatment failure/same parasite strain) from a newly acquired infection (reinfection/different parasite strain) among recurrent parasitemias found during follow-up, a genotype analysis was to be conducted. This analysis was based on the extensive diversity in the following P. falciparum genes: the merozoite surface protein 1 (msp1) and 2 (msp2), and the glutamine-rich protein (glurp) (WHO 2008). The genotypic profiles of pre- and post-parasite strains were to be compared in a stepwise manner to distinguish recrudescence from reinfection. In order to minimize discomfort to the patient due to repeated finger pricks, two to three drops of blood will be collected on a 3MM (Whatman) filter paper during screening or enrollment and each time blood smears are required according to the protocol from day 7. The results of this study will be used to assist the Zanzibar Ministry of Health in assessing the current national treatment guidelines for uncomplicated P. falciparum malaria.