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BackgroundMass drug administration (MDA) is a powerful tool for malaria control, but the medicines to use, dosing, number of rounds, and potential selection of drug resistance remain open questions.MethodsTwo monthly rounds of artemisinin-piperaquine (AP), each comprising 2 daily doses, were administered across the 7 districts of Grande Comore Island. In 3 districts, low-dose primaquine (PMQLD) was also given on the first day of each monthly round. Plasmodium falciparum malaria rates, mortality, parasitemias, adverse events, and genetic markers of potential drug resistance were evaluated.ResultsAverage population coverages of 80%–82% were achieved with AP in 4 districts (registered population 258 986) and AP + PMQLD in 3 districts (83 696). The effectiveness of MDA was 96.27% (95% confidence interval [CI], 95.27%–97.06%; P < .00001) in the 4 AP districts and 97.46% (95% CI, 94.54%–98.82%; P < .00001) in the 3 AP + PMQLD districts. In comparative statistical modeling, the effectiveness of the 2 monthly rounds on Grande Comore Island was nearly as high as that of 3 monthly rounds of AP or AP + PMQLD in our earlier study on Anjouan Island. Surveys of pre-MDA and post-MDA samples showed no significant changes in PfK13 polymorphism rates, and no PfCRT mutations previously linked to piperaquine resistance in Southeast Asia were identified.ConclusionsMDA with 2 monthly rounds of 2 daily doses of AP was highly effective on Grande Comore Island. The feasibility and lower expense of this 2-month versus 3-month regimen of AP may offer advantages for MDA programs in appropriate settings.

Malaria significantly rebounded in 2018 in the Comoros; this created an urgent need to conduct clinical trials to investigate the effectiveness of artemisinin and its derivatives.An open-label, non-randomised controlled trial of artemisinin-piperaquine (AP) and artemether-lumefantrine (AL) was conducted in Grande Comore island from June 2019 to January 2020. A total of 238 uncomplicated falciparum malaria cases were enrolled and divided 1:1 into two treatments. The primary endpoint was the 42-day adequate clinical and parasitological responses (ACPR). Secondary endpoints were parasitaemia and fever clearance at day 3, gametocytes and tolerability.The 42-day ACPR before and after PCR correction were 91.43% (95% CI 83.93-95.76%) and 98.06% (95% CI 92.48-99.66%) for AP treatment, respectively, and 96.00% (95% CI 88.17-98.14%) and 98.97% (95% CI 93.58-99.95%) for AL treatment, respectively. Complete clearance of the parasitaemia and fever for both groups was detected on day 3. Gametocytes disappeared on day 21 in the AP group and on day 2 in AL group. Specifically, the adverse reactions were mild in both groups.It was found that AP and AL maintained their high efficacy and tolerance in the Comoros. Nonetheless, asymptomatic malaria infections bring new challenges to malaria control.

Background. Genomic data is key in understanding the spread and evolution of SARS-CoV-2 pandemic and informing the design and evaluation of interventions. However, SARS-CoV-2 genomic data remains scarce across Africa, with no reports yet from the Indian Ocean islands. Methods. We genome sequenced six SARS-CoV-2 positive samples from the first major infection wave in the Union of Comoros in January 2021 and undertook detailed phylogenetic analysis. Results. All the recovered six genomes classified within the 501Y.V2 variant of concern (also known as lineage B.1.351) and appeared to be from 2 sub-clusters with the most recent common ancestor dated 30th Oct-2020 (95% Credibility Interval: 06th Sep-2020 to 10th Dec-2020). Comparison of the Comoros genomes with those of 501Y.V2 variant of concern from other countries deposited into the GISAID database revealed their close association with viruses identified in France and Mayotte (part of the Comoros archipelago and a France, Overseas Department). Conclusions. The recovered genomes, albeit few, confirmed local transmission following probably multiple introductions of the SARS-CoV-2 501Y.V2 variant of concern during the Comoros’s first major COVID-19 wave. These findings demonstrate the importance of genomic surveillance and have implications for ongoing control strategies on the islands.

BACKGROUND: Mass drug administration (MDA), with or without low-dose primaquine (PMQ(LD)), is being considered for malaria elimination programs. The potential of PMQ(LD) to block malaria transmission by mosquitoes must be balanced against liabilities of its use. METHODS: Artemisinin–piperaquine (AP), with or without PMQ(LD), was administered in 3 monthly rounds across Anjouan Island, Union of Comoros. Plasmodium falciparum malaria rates, mortality, parasitemias, adverse events, and PfK13 Kelch-propeller gene polymorphisms were evaluated. RESULTS: Coverage of 85 to 93% of the Anjouan population was achieved with AP plus PMQ(LD) (AP+PMQ(LD)) in 2 districts (population 97164) and with AP alone in 5 districts (224471). Between the months of April–September in both 2012 and 2013, average monthly malaria hospital rates per 100000 people fell from 310.8 to 2.06 in the AP+PMQ(LD) population (ratio 2.06/310.8 = 0.66%; 95% CI: 0.02%, 3.62%; P = .00007) and from 412.1 to 2.60 in the AP population (ratio 0.63%; 95% CI: 0.11%, 1.93%; P < .00001). Effectiveness of AP+PMQ(LD) was 0.9908 (95% CI: 0.9053, 0.9991), while effectiveness of AP alone was 0.9913 (95% CI: 0.9657, 0.9978). Both regimens were well tolerated, without severe adverse events. Analysis of 52 malaria samples after MDA showed no evidence for selection of PfK13 Kelch-propeller mutations. CONCLUSIONS: Steep reductions of malaria cases were achieved by 3 monthly rounds of either AP+PMQ(LD) or AP alone, suggesting potential for highly successful MDA without PMQ(LD) in epidemiological settings such as those on Anjouan. A major challenge is to sustain and expand the public health benefits of malaria reductions by MDA.

Background Malaria is still one of the serious public health problems in Grande Comore Island, although the number of annual cases has been greatly reduced in recent years. A better understanding of malaria parasite population diversity and transmission dynamics is critical for assessing the effectiveness of malaria control measures. The objective of this study is to investigate temporal changes in genetic diversity of Plasmodium falciparum populations and multiplicity of infection (MOI) in Grande Comore 10 years after introduction of ACT. Methods A total of 232 P. falciparum clinical isolates were collected from the Grande Comore Island during two sampling periods (118 for 2006‒2007 group, and 114 for 2013‒2016 group). Parasite isolates were characterized for genetic diversity and complexity of infection by genotyping polymorphic regions in merozoite surface protein gene 1 (msp-1), msp-2, and msp-3 using nested PCR and DNA sequencing. Results Three msp-1 alleles (K1, MAD20, and RO33), two msp-2 alleles (FC27 and 3D7), and two msp-3 alleles (K1 and 3D7) were detected in parasites of both sampling periods. The RO33 allele of msp-1 (84.8%), 3D7 allele of msp-2 (90.8%), and K1 allele of msp-3 (66.7%) were the predominant allelic types in isolates from 2006–2007 group. In contrast, the RO33 allele of msp-1 (63.4%), FC27 allele of msp-2 (91.1%), and 3D7 allele of msp-3 (53.5%) were the most prevalent among isolates from the 2013–2016 group. Compared with the 2006‒2007 group, polyclonal infection rates of msp-1 (from 76.7 to 29.1%, P

Background Plasmodium falciparum malaria is a significant public health problem in Comoros, and artemisinin combination therapy (ACT) remains the first choice for treating acute uncomplicated P. falciparum. The emergence and spread of artemisinin-resistant P. falciparum in Southeast Asia, associated with mutations in K13-propeller gene, poses a potential threat to ACT efficacy. Detection of mutations in the P. falciparum K13-propeller gene may provide the first-hand information on changes in parasite susceptibility to artemisinin. The objective of this study is to determinate the prevalence of mutant K13-propeller gene among the P. falciparum isolates collected from Grande Comore Island, Union of Comoros, where ACT has been in use since 2004. Methods A total of 207 P. falciparum clinical isolates were collected from the island during March 2006 and October 2007 (n = 118) and March 2013 and December 2014 (n = 89). All isolates were analysed for single nucleotide polymorphisms (SNPs) and haplotypes in the K13-propeller gene using nested PCR and DNA sequencing. Results Only three 2006–2007 samples carried SNPs in the K13-propeller gene, one having a synonymous (G538G) and the other having two non-synonymous (S477Y and D584E) substitutions leading to two mutated haplotypes (2.2 %, 2/95). Three synonymous mutations (R471R, Y500Y, and G538G) (5.9 %, 5/85) and 7 non-synonymous substitutions (21.2 %, 18/85) with nine mutated haplotypes (18.8 %, 16/85) were found in isolates from 2013 to 2014. However, none of the polymorphisms associated with artemisinin-resistance in Southeast Asia was detected from any of the parasites examined. Conclusion This study showed increased K13-propeller gene diversity among P. falciparum populations on the Island over the course of 8 years (2006–2014). Nevertheless, none of the polymorphisms known to be associated with artemisinin resistance in Asia was detected in the parasite populations examined. Our data suggest that P. falciparum populations in Grande Comore are still effectively susceptible to artemisinin. Our results provide insights into P. falciparum populations regarding mutations in the gene associated with artemisinin resistance and will be useful for developing and updating anti-malarial guidance in Comoros.

Background In Comoros, the widespread of chloroquine (CQ)-resistant Plasmodium falciparum populations was a major obstacle to malaria control, which led to the official withdrawal of CQ in 2004. Continuous monitoring of CQ-resistant markers of the P. falciparum CQ resistant transporter (pfcrt) and the P. falciparum multiple drug resistance 1 (pfmdr-1) is necessary inder to obtain first-hand information on CQ susceptibility of parasite populations in the field. The objective of this study is to assess the prevalence and evolution of CQ-resistance in the P. falciparum populations on the Comoros’ Grande Comore island after withdrawal of CQ. Methods A total of 207 P. falciparum clinical isolates were collected from the island, including 118 samples from 2006 to 2007 and 89 samples from 2013 to 2014. Nucleotide substitutions in the pfcrt and pfmdr-1 genes linked to CQ response in parasite isolates were assessed using nested PCR and DNA sequencing. Results From the pfcrt gene segment sequenced, we detected C72S, M74I, N75E, and K76T substitutions in the parasite isolates collected from both 2006–2007 to 2013–2014 periods. Significant decline of pfcrt resistant alleles at C72S (42.6 to 6.9 %), M74I (39.1 to 14.9 %), N75E (63.5 to 18.3 %), and K76T (72.2 to 19.5 %) from 2006–2007 to 2013–2014 were observed, and the frequency of pfcrt wild type allele was significantly increased from 19.1 % in 2006–2007 to 75.8 % in 2013–2014. Sequence analysis of pfmdr-1 also detected point mutations at codons N86Y, Y184F, and D1246Y, but not S1034C and N1042D, in the isolates collected from both examined periods. An increasing trend in the prevalence of the pfmdr-1 wild type allele (NYD, 4.3 % in 2006–2007; and 28.7 % in 2013–2014), and a decreasing trend for pfmdr-1 N86Y mutation (87.0 % in 2006–2007; and 40.2 % in 2013–2014) were observed in our samples. Conclusions The present data indicate that the prevalence and patterns of mutant pfcrt and pfmdr-1 dramatically decreased in the Grande Comore isolates from 2006 to 2014, suggesting that the CQ-sensitive P. falciparum strains have returned after the withdrawal of CQ. The data also suggests that the parasites with wild type pfcrt/pfdmr-1 genes may have growth and/or transmission advantages over the mutant parasites. The information obtained from this study will be useful for developing and updating anti-malarial treatment policy in Grande Comore island.