The Lancet Infectious Diseases
Jun 2014 Volume 14 Number 6 p441 – 532
http://www.thelancet.com/journals/laninf/issue/current

Comment
In for the long haul: 20 years of malaria surveillance
Chris Drakeley, Jo Lines
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The past 20 years have seen many changes in malaria control. In most countries where malaria is endemic, first-line treatment has switched several times as drug resistance has developed, moving from chloroquine through to artemisinin-based combination therapies. In the past decade, thanks to increased funding through the Global Fund to Fight AIDS, Tuberculosis and Malaria, coverage of long-lasting insecticide-treated nets (LLINs) has massively expanded. These efforts have led to a substantial reduction in the incidence of malaria mortality,1 with a cumulative total of about 3•3 million deaths prevented since 2001, according to the 2013 World Malaria Report.

The rise and fall of malaria in a west African rural community, Dielmo, Senegal, from 1990 to 2012: a 22 year longitudinal study
Dr Jean-François Trape MD a, Adama Tall MD b, Cheikh Sokhna PhD a, Alioune Badara Ly MD c, Nafissatou Diagne PhD a, Ousmane Ndiath PhD a, Catherine Mazenot PhD a, Vincent Richard MD b, Abdoulaye Badiane BSc b, Fambaye Dieye-Ba BSc a, Joseph Faye BSc b, Gora Ndiaye a, Fatoumata Diene Sarr MD b, Clémentine Roucher PhD a, Charles Bouganali a, Hubert Bassène BSc a, Aissatou Touré-Baldé PhD d, Christian Roussilhon PhD d e, Ronald Perraut PhD d e, Prof André Spiegel MD b, Jean-Louis Sarthou PhD d, Prof Luiz Pereira da Silva e, Odile Mercereau-Puijalon PhD e, Pierre Druilhe MD e, Prof Christophe Rogier MD b f
Summary
Background
A better understanding of the effect of malaria control interventions on vector and parasite populations, acquired immunity, and burden of the disease is needed to guide strategies to eliminate malaria from highly endemic areas. We monitored and analysed the changes in malaria epidemiology in a village community in Senegal, west Africa, over 22 years.
Methods
Between 1990 and 2012, we did a prospective longitudinal study of the inhabitants of Dielmo, Senegal, to identify all episodes of fever and investigate the relation between malaria host, vector, and parasite. Our study included daily medical surveillance with systematic parasite detection in individuals with fever. We measured parasite prevalence four times a year with cross-sectional surveys. We monitored malaria transmission monthly with night collection of mosquitoes. Malaria treatment changed over the years, from quinine (1990—94), to chloroquine (1995—2003), amodiaquine plus sulfadoxine-pyrimethamine (2003—06), and finally artesunate plus amodiaquine (2006—12). Insecticide-treated nets (ITNs) were introduced in 2008.
Findings
We monitored 776 villagers aged 0—101 years for 2 378 150 person-days of follow-up. Entomological inoculation rate ranged from 142•5 infected bites per person per year in 1990 to 482•6 in 2000, and 7•6 in 2012. Parasite prevalence in children declined from 87% in 1990 to 0•3 % in 2012. In adults, it declined from 58% to 0•3%. We recorded 23 546 fever episodes during the study, including 8243 clinical attacks caused by Plasmodium falciparum, 290 by Plasmodium malariae, and 219 by Plasmodium ovale. Three deaths were directly attributable to malaria, and two to severe adverse events of antimalarial drugs. The incidence of malaria attacks ranged from 1•50 attacks per person-year in 1990 to 2•63 in 2000, and to only 0•046 in 2012. The greatest changes were associated with the replacement of chloroquine and the introduction of ITNs.
Interpretation
Malaria control policies combining prompt treatment of clinical attacks and deployment of ITNs can nearly eliminate parasite carriage and greatly reduce the burden of malaria in populations exposed to intense perennial malaria transmission. The choice of drugs seems crucial. Rapid decline of clinical immunity allows rapid detection and treatment of novel infections and thus has a key role in sustaining effectiveness of combining artemisinin-based combination therapy and ITNs despite increasing pyrethroid resistance.
Funding
Pasteur Institutes of Dakar and Paris, Institut de Recherche pour le Développement, and French Ministry of Cooperation.