Open Access Highly Accessed Research

A controlled, parallel, cluster-randomized trial of community-wide screening and treatment of asymptomatic carriers of Plasmodium falciparum in Burkina Faso

Alfred B Tiono1*, Alphonse Ouédraogo1, Bernhards Ogutu2, Amidou Diarra1, Sam Coulibaly1, Adama Gansané1, Sodiomon B Sirima1, Gregory O’Neil3, Amitava Mukhopadhyay4 and Kamal Hamed5

Author Affiliations

1 Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso

2 Centre for Clinical Research, Kenya Medical Research Institute, Nairobi, Kenya

3 Novartis Pharma AG, Basel, Switzerland

4 Novartis Healthcare Private Limited, Hyderabad, India

5 Novartis Pharmaceuticals Corporation, East Hanover, NJ, USA

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Malaria Journal 2013, 12:79  doi:10.1186/1475-2875-12-79

Published: 27 February 2013

Abstract

Background

In malaria-endemic countries, large proportions of infected individuals are asymptomatic, constituting a reservoir of parasites for infection of newly hatched mosquitoes. This study evaluated the impact of screening and treatment of asymptomatic carriers of Plasmodium falciparum.

Methods

Eighteen villages were randomized (1:1) to study arms and inhabitants participated in four community screening campaigns: three before the rainy season ~1 month apart, and the fourth after the rains at ~12 months. On day 1 of campaigns 1–3, asymptomatic carriers in the intervention arm were identified by rapid diagnostic test and treated with artemether-lumefantrine. Outcomes were symptomatic malaria with parasite density >5,000/μL per person-year in children <5 years and change in haemoglobin between days 1 and 28 of campaign 1.

Results

At 12 months, the number of symptomatic malaria episodes with a parasite density >5,000/μL per person-year in children <5 years was not significantly different between arms (1.69 vs 1.60, p = 0.3482). Mean haemoglobin change in asymptomatic carriers during campaign 1 was greater in the intervention vs control arm (+0.53 g/dL vs -0.21 g/dL, p <0.0001). ANCOVA demonstrated that mean asymptomatic carriage at the cluster level was lower in the intervention vs control arm at day 1 of campaigns 2 (5.0% vs 34.9%, p <0.0001) and 3 (3.5% vs 31.5%, p <0.0001), but showed only a small difference at day 1 of campaign 4 (34.6% vs 37.6%, p = 0.2982). Mean gametocyte carriage was lower in the intervention vs control arm at day 1 of campaigns 2 and 3 (0.7% vs 5.4%, p <0.0001; 0.5% vs 5.8%, p <0.0001), but was similar at day 1 of campaign 4 (4.9% vs 5.1%, p = 0.7208).

Conclusions

Systematic screening and treatment of asymptomatic carriers at the community level did not reduce clinical malaria incidence in the subsequent transmission season, indicating greater levels of parasite clearance are required to achieve a sustained impact in this setting.

Keywords:
Malaria; Plasmodium falciparum; Asymptomatic carriers; Mass screening; Transmission; Artemether-lumefantrine