Major decline in malaria morbidity and mortality in the Union of Comoros between 2010 and 2014: The effect of a combination of prevention and control measures

Background. Malaria remains a public health challenge in sub-Saharan Africa. In response to this, many countries are working towards achieving the World Health Assembly and Roll Back Malaria Partnership target of a 75% decline in malaria incidence.Objective. To assess trends in malaria morbidity and mortality in the three islands of the Comoros Archipelago from 2010 to 2014.Methods. This was a retrospective study in which all confirmed malaria cases and deaths recorded between 2010 and 2014 were accessed from the national malaria control database. Trends and comparisons in malaria incidence and case fatality rates for all age groups, including under-5 children and pregnant women, were analysed using Microsoft Excel and SPSS version 16.Results. A substantial decline in malaria incidence was observed for each island between 2010 and 2014; from 75.98 cases per 1 000 population in 2010 to 0.14 in 2014 in Moheli, 60.60 to 0.02 in Anjouan and 235.36 to 5.47 in Grand Comoro. Additionally, a general reduction in malaria case fatalities was observed. In Moheli, there were no case fatalities between 2010 and 2014, while there was a decline in the case fatality rate in Anjouan (from 1.20 fatalities per 1 000 cases to 0) and Grand Comoros (0.51 to 0). There were also significant differences (p<0.05) in malaria incidence and case fatalities between the three islands. A similar trend was observed for pregnant women and under-5 children.Conclusions. Our study indicates a significant decline in malaria morbidity and mortality in the islands of Moheli, Anjouan and Grand Comoro from 2010 to 2014. This considerable reduction is attributed to a combination of malaria prevention and control interventions implemented during the study period

Genetic Structure of Plasmodium falciparum and Elimination of Malaria, Comoros Archipelago

Elimination interventions should be implemented simultaneously throughout the entire archipelago

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,

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

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

Distribution of Plasmodium species on the island of Grande Comore on the basis of DNA extracted from rapid diagnostic tests

In the Union of Comoros, interventions for combating malaria have contributed to a spectacular decrease in the prevalence of the disease. We studied the current distribution of Plasmodium species on the island of Grande Comore using nested PCR. The rapid diagnostic tests (RDTs) currently used in the Comoros are able to identify Plasmodium falciparum but no other Plasmodium species. In this study, we tested 211 RDTs (158 positive and 53 negative). Among the 158 positive RDTs, 22 were positive for HRP2, 3 were positive only for pLDH, and 133 were positive for HRP2 and pLDH. DNA was extracted from a proximal part of the nitrocellulose membrane of RDTs. A total of 159 samples were positive by nested PCR. Of those, 156 (98.11%) were positive for P. falciparum, 2 (1.25%) were positive for P. vivaxI, and 1 (0.62%) was positive for P. malariae. None of the samples were positive for P. ovale. Our results show that P. falciparum is still the most dominant species on the island of Grande Comore, but P. vivax and P. malariae are present at a low prevalence

Serologic Evidence of Leptospirosis in Humans, Union of the Comoros, 2011

International audienceTo improve knowledge of Leptospira infection in the southwestern Indian Ocean islands, we conducted a study in the Union of the Comoros to serologically assess the presence or absence of leptospirosis in humans. The Union of the Comoros consists of 3 islands: Grande-Comore, Mohéli, and Anjouan. Together with a fourth, southern island, Mayotte, these islands form the Comoros Archipelago

Genetic diversity of Plasmodium falciparum in Grande Comore Island

BackgroundDespite several control interventions resulting in a considerable decrease in malaria prevalence in the Union of the Comoros, the disease remains a public health problem with high transmission in Grande Comore compared to neighbouring islands. In this country, only a few studies investigating the genetic diversity of Plasmodium falciparum have been performed so far. For this reason, this study aims to examine the genetic diversity of P. falciparum by studying samples collected in Grande Comore in 2012 and 2013, using merozoite surface protein 1 (msp1), merozoite surface protein 2 (msp2) and single nucleotide polymorphism (SNP) genetic markers.MethodsA total of 162 positive rapid diagnostic test (RDT) samples from Grande Comore were used to extract parasite DNA. Allelic families K1, Mad20 and RO33 of the msp1 gene as well as allelic families IC3D7 and FC37 of the msp2 gene were determined by using nested PCR. Additionally, 50 out of 151 samples were genotyped to study 24 SNPs by using high resolution melting (HRM).ResultsTwo allelic families were predominant, the K1 family of msp1 gene (55%) and the FC27 family of msp2 gene (47.4%). Among 50 samples genotyped for 24 SNPs, 42 (84%) yielded interpretable results. Out of these isolates, 36 (85%) were genetically unique and 6 (15%) grouped into two clusters. The genetic diversity of P. falciparum calculated from msp1 and msp2 genes and SNPs was 0.82 and 0.61, respectively.ConclusionIn summary, a large genetic diversity of P. falciparum was observed in Grande Comore. This may favour persistence of malaria and might be one of the reasons for the high malaria transmission compared to neighbouring islands. Further surveillance of P. falciparum isolates, mainly through environmental management and vector control, is warranted until complete elimination is attained