Abstract
BackgroundIn 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.MethodsEighteen 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.ResultsAt 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).ConclusionsSystematic 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.
Highlights
In malaria-endemic countries, large proportions of infected individuals are asymptomatic, constituting a reservoir of parasites for infection of newly hatched mosquitoes
Even in areas of highly seasonal malaria transmission, studies have shown that a considerable proportion of the population remain positive for parasitaemia throughout the year [1,3]
In addition to constituting a parasite reservoir responsible for malaria transmission, individuals with asymptomatic parasitaemia are at risk of developing anaemia and may progress to symptomatic malaria
Summary
In malaria-endemic countries, large proportions of infected individuals are asymptomatic, constituting a reservoir of parasites for infection of newly hatched mosquitoes. The systematic identification and treatment of asymptomatic carriers could potentially reduce disease transmission by reducing the pool of parasites carried by these individuals This hypothesis is supported by a modelling and simulation analysis that evaluated the impact of community screening campaigns followed by treatment of asymptomatic carriers with artemether-lumefantrine (AL) (CoartemW, Novartis Pharma AG, Basel, Switzerland) [6]. This simulation suggested campaign visits placed in close succession in the period prior to the malaria transmission season should effectively clear asymptomatic infection from communities and significantly reduce the subsequent incidence of disease in those communities [6]. Similar predictions were obtained by Okell et al in their modelling of the impact of two mass treatment strategies [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
