Control of malaria in the Comoro Islands over the past century

International audienceBACKGROUND:The Comoros are an archipelago located in the Indian Ocean between the eastern coasts of Africa and north of Madagascar. Malaria transmission appeared late in the 19th century due to the intensification of human migration. The story of malaria transmission for the past century is depicted to provide useful lessons for the future. Currently, malaria transmission occurs differently on each island; thus, control strategies must be adapted for each particular island. Tentative malaria control in Comoros has a long history of success and failure. This study reviews the data available as a basis for recommendations for the future.RESULTS:There has been much effort to reach a pre-eradication state in Anjouan and Moheli, but only control steps have been taken in the Great Comoro. To date, the primary strategy used is mass treatment of the population using artemisinin-based combination therapy (ACT), which is similar to the strategy deployed during the 1950s in other countries. ACT appears efficient in two of the three islands; however, the sustainability of the strategy is unknown. This sustainability is compromised by (i) the huge level of uncontrolled exchange between the Comoro Islands and their neighbours, increasing the risk of introducing ACT-resistant strains, (ii) the use of large quantities of pesticides for agriculture usually associated with the resistance of mosquitoes, and (iii) the cost of the actions themselves.CONCLUSIONS:In view of the history of malaria in this area, the first recommendation is to enhance the training of health workers and the population. The second step is to establish a national strategy to assess malaria and related factors, which is currently lacking. A survey to assess the drug sensitivity of the parasites is particularly important in a context of low transmission associated with mass treatment of the population. The last point should be to secure financial support, which is not obvious in a context of pre-elimination. The Comoro Islands are thus a living laboratory to experiments with strategies for elimination, but the future is complex

Malaria and environment : Search for specific landscape indicators of its distribution in the village of Grande Comore

International audienceMalaria has long been endemic in the Union of Comoros. Grande Comore has experienced the highest rates of malaria among the Comorian islands for 90 years. Between 2010 and 2016, more than 82% of reported malaria cases were reported to the Grande Comore. Maintaining a high incidence rate of malaria on the island of Grande Comore, unlike the remaining islands, intrigues malaria control leaders in the Union of the Comoros. This study aims at describing the spatial patterns of the epidemiology of malaria and at identifying environmental indicators through a geographical approach in Grande Comore. Monthly cases, as reported by the ?Programme National de lutte Contre le paludisme? (PNLP) in 2016, were geo-referenced in the island of Grande Comore, at two different scales: by health district and villages. Using SPOT 5 satellite images of Grande Comore, we described and classified the land use by an Object-Based Image Analysis (OBIA) method. We used this classification to calculate landscape metrics within 1km, 1.5km and 2km radius of each village (percentage of surface area covered by each land use class, the patch and edge densities). We realized statistical and spatial analyses to show the relationships between malaria and environmental information. We applied the Global Moran's I and the Anselin Local Moran's I to test spatial correlation of malaria incidence between villages. In 2016, 1,372 malaria cases were recorded in 116 villages. The average incidence of all the villages was 301 cases per 100,000 inhabitants. We observed significant and positive correlation between malaria incidence with grassland (RR=0.03,

Towards the elimination of malaria in the Union of Comoros: geographical insight on control actions and maintenance factors

International audienceIntroduction: Malaria has long been endemic in the Union of Comoros. Since 2007, the Comorian government has been conducting a national strategy for eradicating malaria by 2016. Between 2010 and 2014, the number of malaria cases has radically fallen by more than 90%. This study aims at describing the spatial patterns of the epidemiology of malaria and at identifying risk factors through a geographical approach. Method: Monthly cases, as reported by the “Programme National de lutte Contre le paludisme” (PNLP) from 2010 to 2014, were geo-referenced in the three islands (i.e. Grande Comore, Moheli and Anjouan) at two different scales: by sanitary district and by health center. In Grande Comore, malaria cases confirmed by microscopic exam during the active control from 2012 to 2014 were geo-localized at the village scale. Data on environmental factors, including meteorology and land use (analyzed by remote sensing of SPOT 5 satellite images) but also information on malaria control actions were integrated into a spatial database. We realized statistical and spatial analyses to show the relationships between this dataset and malaria information.Results: The mapping of malaria incidence reveals spatial and temporal variations between and within islands. In the 7 districts of Anjouan and in 2 of the 3 districts of Moheli, the incidence is less than 1 case per 100,000 inhabitants in 2014. In contrast, the incidence remains higher in every health district of Grande Comore with more than 4 cases per 100,000 inhabitants in 2014. This is consistent with the reduction of prevalence of Plasmodium falciparum that decreased from 24% in 2012 to 2 in 2014 in Grande Comore. Also, Long before the two other islands, Moheli has benefited from a campaign of indoor insecticide spraying and a population mass treatment by Artequick and Primaquine between 2007 and 2009. In addition, we highlight spatial relationships between malaria incidences and environmental factors in Grande Comore.Conclusion: This study clarifies the impact of control actions on malaria epidemiology and the environmental factors that contributed to its maintenance

Changing Patterns of Malaria in Grande Comore after a Drastic Decline: Importance of Fine-Scale Spatial Analysis to Inform Future Control Actions

International audienceMalaria has long been endemic in the Union of Comoros reaching an incidence of 15,045 cases for 100,000 inhabitants in 2010 (103,670 cases). Since then, strengthened control actions based on the distribution of Long-Lasting Insecticidal mosquito Nets and mass treatment have reduced malaria to a low level. However, it persists more specifically in Grande Comore, where 82% of cases were diagnosed between 2010 and 2016. This situation remains a challenge for health authorities seeking to eliminate malaria, by targeting transmission sites more precisely. In this context, this study aimed at mapping malaria at the finest scale, in order to describe its spatial distribution and identify possible environmental indicators. The National Malaria Control Program provided the 2016 data, the only year that could be mapped at the level of localities. This mapping revealed spatial autocorrelation between localities, especially in the east of the island with a major cluster around Itsinkoudi (using the Kulldorff’s spatial scan test). Secondary clusters showed that malaria remains present throughout the island in both rural and urban areas. We also analyzed satellite images (SPOT 5) with remote sensing techniques (Object-Based Image Analysis) to look for environmental indicators. Landscape analysis shows that malaria incidence is correlated across the island with low altitudes, and a larger proportion of grasslands or a fewer proportion of forested areas nearby (at less than 1km around villages). More locally in the east, malaria is linked to larger shrub areas. These relationships could be associated with the fact that lower altitude localities are more interconnected, such facilitating malaria transmission. In 2016, malaria persists in Grande Comore, showing new patterns with more cases in the eastern part of the island and the possibility of high incidences during the dry season. Precise mapping of epidemiological data and landscape analysis allow the identification of clusters and active transmission foci. They are important tools for health surveillance in order to optimize control actions on key transmission locations

MALDI-TOF MS identification of Anopheles gambiae Giles blood meal crushed on Whatman filter papers

International audienceBackground: Identification of the source of mosquito blood meals is an important component for disease control and surveillance. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling has emerged as an effective tool for mosquito blood meal identification, using the abdomens of freshly engorged mosquitoes. In the field, mosquito abdomens are crushed on Whatman filter papers to determine the host feeding patterns by identifying the origin of their blood meals. The aim of this study was to test whether crushing engorged mosquito abdomens on Whatman filter papers was compatible with MALDI-TOF MS for mosquito blood meal identification. Both laboratory reared and field collected mosquitoes were tested.Material and methods: Sixty Anopheles gambiae Giles were experimentally engorged on the blood of six distinct vertebrate hosts (human, sheep, rabbit, dog, chicken and rat). The engorged mosquito abdomens were crushed on Whatman filter papers for MALDI-TOF MS analysis. 150 Whatman filter papers, with mosquitoes engorged on cow and goat blood, were preserved. A total of 77 engorged mosquito abdomens collected in the Comoros Islands and crushed on Whatman filter papers were tested with MALDI-TOF MS. Results The MS profiles generated from mosquito engorged abdomens crushed on Whatman filter papers exhibited high reproducibility according to the original host blood. The blood meal host was correctly identified from mosquito abdomens crushed on Whatman filter papers by MALDI-TOF MS. The MS spectra obtained after storage were stable regardless of the room temperature and whether or not they were frozen. The MS profiles were reproducible for up to three months. For the Comoros samples, 70/77 quality MS spectra were obtained and matched with human blood spectra. This was confirmed by molecular tools.Conclusion: The results demonstrated that MALDI-TOF MS could identify mosquito blood meals from Whatman filter papers collected in the field during entomological surveys. The application of MALDI-TOF MS has proved to be rapid and successful, making it a new and efficient tool for mosquito-borne disease surveillance

Application of the Relationship-Based Model to Engagement for Field Trials of Genetically Engineered Malaria Vectors.

The transition of new technologies for public health from laboratory to field is accompanied by a broadening scope of engagement challenges. Recent developments of vector control strategies involving genetically engineered mosquitoes with gene drives to assist in the eradication of malaria have drawn significant attention. Notably, questions have arisen surrounding community and regulatory engagement activities and of the need for examples of models or frameworks that can be applied to guide engagement. A relationship-based model (RBM) provides a framework that places stakeholders and community members at the center of decision-making processes, rather than as recipients of predetermined strategies, methods, and definitions. Successful RBM application in the transformation of healthcare delivery has demonstrated the importance of open dialogue and relationship development in establishing an environment where individuals are actively engaged in decision-making processes regarding their health. Although guidelines and recommendations for engagement for gene drives have recently been described, we argue here that communities and stakeholders should lead the planning, development, and implementation phases of engagement. The RBM provides a new approach to the development of ethical, transparent, and effective engagement strategies for malaria control programs

MALDI-TOF MS spectra from <i>An</i>. <i>gambiae</i> Giles (<i>Ang</i>) abdomen protein extracts engorged on vertebrate host bloods and then crushed on Whatman filter papers (WFPs).

<p>The MS spectra were generated according to two protocols (P1, P2). Intact <i>Ang</i> match the MS profiles from <i>Anopheles gambiae</i> Giles abdomens crushed on WFPs. The blood-free WFP corresponds to the MS profiles of WFPs where no mosquito blood meal was released. The vertebrate host bloods used for <i>Anopheles gambiae</i> Giles bloody Whatman filter papers (bloody WFPs) were human and sheep. All mosquitoes were collected 12 hours after feeding. a.u. arbitrary units; m/z mass-to-charge ratio.</p

Blind tests of the <i>An</i>. <i>gambiae</i> Giles used to set up the protocol optimal for blood meals identification by MALDI TOF from BWFPs.

<p>Blind tests of the <i>An</i>. <i>gambiae</i> Giles used to set up the protocol optimal for blood meals identification by MALDI TOF from BWFPs.</p

<i>An</i>. <i>gambiae</i> Giles abdomen crushing in paper filter Whatman to performed the blind tests according blood meal source.

<p><i>An</i>. <i>gambiae</i> Giles abdomen crushing in paper filter Whatman to performed the blind tests according blood meal source.</p