Seasonality and shift in age-specific malaria prevalence and incidence in Binko and Carrière villages close to the lake in Selingué, Mali

BACKGROUND: Malaria transmission in Mali is seasonal and peaks at the end of the rainy season in October. This study assessed the seasonal variations in the epidemiology of malaria among children under 10 years of age living in two villages in Selingué: Carrière, located along the Sankarani River but distant from the hydroelectric dam, and Binko, near irrigated rice fields, close to the dam. The aim of this study was to provide baseline data, seasonal pattern and age distribution of malaria incidence in two sites situated close to a lake in Selingué. METHODS: Geographically, Selingué area is located in the basin of Sakanrani and belongs to the district of Yanfolila in the third administrative region of Mali, Sikasso. Two cross-sectional surveys were conducted in October 2010 (end of transmission season) and in July 2011 (beginning of transmission season) to determine the point prevalence of asymptomatic parasitaemia, and anaemia among the children. Cumulative incidence of malaria per month was determined in a cohort of 549 children through active and passive case detection from November 2010 through October 2011. The number of clinical episodes per year was determined among the children in the cohort. Logistic regression was used to determine risk factors for malaria. RESULTS: The prevalence of malaria parasitaemia varied significantly between villages with a strong seasonality in Carrière (52.0–18.9 % in October 2010 and July 2011, respectively) compared with Binko (29.8–23.8 % in October 2010 and July 2011, respectively). Children 6–9 years old were at least twice more likely to carry parasites than children up to 5 years old. For malaria incidence, 64.8–71.9 % of all children experienced at least one episode of clinical malaria in Binko and Carrière, respectively. The peak incidence was observed between August and October (end of the rainy season), but the incidence remained high until December. Surprisingly, the risk of clinical malaria was two- to nine-fold higher among children 5–9 years old compared to younger children. CONCLUSIONS: A shift in the peak of clinical episodes from children under 5–9 years of age calls for expanding control interventions, such as seasonal malaria chemoprophylaxis targeting the peak transmission months

Perspectives of people in Mali toward genetically-modified mosquitoes for malaria control

Background: Genetically-modified (GM) mosquitoes have been proposed as part of an integrated vector control strategy for malaria control. Public acceptance is essential prior to field trials, particularly since mosquitoes are a vector of human disease and genetically modified organisms (GMOs) face strong scepticism in developed and developing nations. Despite this, in sub-Saharan Africa, where the GM mosquito effort is primarily directed, very little data is available on perspectives to GMOs. Here, results are presented of a qualitative survey of public attitudes to GM mosquitoes for malaria control in rural and urban areas of Mali, West Africa between the months of October 2008 and June 2009. Methods: The sample consisted of 80 individuals - 30 living in rural communities, 30 living in urban suburbs of Bamako, and 20 Western-trained and traditional health professionals working in Bamako and Bandiagara. Questions were asked about the cause of malaria, heredity and selective breeding. This led to questions about genetic alterations, and acceptable conditions for a release of pest-resistant GM corn and malaria-refractory GM mosquitoes. Finally, participants were asked about the decision-making process in their community. Interviews were transcribed and responses were categorized according to general themes. Results: Most participants cited mosquitoes as one of several causes of malaria. The concept of the gene was not widely understood; however selective breeding was understood, allowing limited communication of the concept of genetic modification. Participants were open to a release of pest-resistant GM corn, often wanting to conduct a trial themselves. The concept of a trial was reapplied to GM mosquitoes, although less frequently. Participants wanted to see evidence that GM mosquitoes can reduce malaria prevalence without negative consequences for human health and the environment. For several participants, a mosquito control programme was preferred; however a transgenic release that satisfied certain requirements was usually acceptable. Conclusions: Although there were some dissenters, the majority of participants were pragmatic towards a release of GM mosquitoes. An array of social and cultural issues associated with malaria, mosquitoes and genetic engineering became apparent. If these can be successfully addressed, then social acceptance among the populations surveyed seems promising

Mean wing length (mm) in females (dark bars) and males (light bars) from the 4 Genetic/Environmental treatments in the 2011 assortative mating experiment.

<p>For each gender, levels labelled with different letters differed significantly in pairwise statistical comparisons (Tukey test). Error bars are 95% confidence intervals.</p

Mean female and male body size, survival and insemination rate in relation to Genetic/Environmental treatment in the within-form mating experiment (1^st experiment).

<p>The insemination rate of females of each treatment exposed to Field/Field Mopti males.</p><p>Here the insemination rate of Field/Field Mopti females exposed to males of each treatment group.</p><p>Values in brackets are 95% confidence intervals and sample sizes are indicated in italics.</p

Mean female and male body size, survival and insemination rate in relation to Genetic/Environmental treatment in the assortative mating experiment (2^nd experiment).

<p>The insemination rate of females of each treatment exposed to Field/Field Mopti males.</p><p>Here the insemination rate of Field/Field Mopti females exposed to males of each treatment group.</p><p>Values in brackets are 95% confidence intervals and sample sizes are indicated in italics.</p

Percentages (dark columns and left axis) and Log Odds estimates (light columns and right axis) of survival and mating rates in males and females from 4 combinations of genetic/environmental backgrounds after 2 nights under semi-field conditions in the 2010–2011 within-form mating experiment.

<p>A–B: Survival of treatment females and males; C–D: Mating rate of treatment females and males. For each gender, levels labelled with different letters differed significantly in pairwise statistical comparisons (Tukey test). Error bars represent 95% confidence intervals.</p

Nominal logistic regressions of the effects of Year, Genetic/Environmental treatment, and Enclosure on female and male survival in within-form mating experiment (1^st experiment).

<p>Square brackets indicate effect nesting.</p><p>Sample sizes were 900 females and 900 males.</p