Evidence that seasonal malaria chemoprevention with SPAQ influences blood and pre-erythrocytic stage antibody responses of Plasmodium falciparum infections in Niger.

BACKGROUND: In endemic areas, children develop slowly and naturally anti-Plasmodium antibodies and become semi-immune. Seasonal Malaria Chemoprevention (SMC) with sulfadoxine-pyrimethamine + amodiaquine (SPAQ) is a new strategy to reduce malaria morbidity in West African young children. However, SMC may impact on the natural acquisition of anti-Plasmodium immunity. This paper evaluates the effect of SMC with SPAQ on antibody concentration in young children from Niger. METHODS: This research was conducted in areas benefitting from SMC since 2014 (Zinder district), without SMC (Dosso district), and with 1 year of SMC since 2016 (Gaya district). To assess the relationship between SMC and Plasmodium falciparum IgG antibody responses, the total antibody concentrations against two P. falciparum asexual stage vaccine candidate antigens, circumsporozoite protein (CSP) and glutamate-rich protein R2 (GLURP-R2), in children aged 3 to 59 months across the three areas were compared. Antibody concentrations are quantified using an enzyme-linked immunosorbent assay on the elution extracted from positive and negative malaria Rapid Diagnostic Test cassettes. RESULTS: The analysis concerns two hundred and twenty-nine children aged from 3 to 59 months: 71 in Zinder, 77 in Dosso, and 81 in Gaya. In Zinder (CSP = 17.5 µg/ml and GLURP-R2 = 14.3 µg/ml) median antibody concentration observed are higher than in Gaya (CSP = 7.7 µg/ml and GLURP-R2 = 6.5 µg/ml) and Dosso (CSP = 4.5 µg/ml and GLURP-R2 = 3.6 µg/ml) (p < 0.0001). CONCLUSION: The research reveals some evidences which show that seasonal malaria chemoprevention with SPAQ has an effect on blood stage antibody responses and pre-erythrocytic stage of P. falciparum infections in Niger. Increased antibody titres with increased SMC/SPAQ implementation. This contradicts hypothesis that SMC/SPAQ could reduce immunity to erythrocyte and liver-stage antigens. Further studies are necessary to provide better understanding of the SMC effect on malaria immunity.

Factors associated with COVID-19 in children aged 0 to 15 in Niger, 2020.

On January 30, 2020, the WHO declared COVID-19 a global health emergency. Children were affected in less severe forms. Niger had implemented measures in a context where children were a source of contamination. The aim was to determine the factors associated with COVID-19 in children in Niger from February to August 2020 through an analysis of the national database. We conducted an analytical cross-sectional study including all COVID-19 suspects in the database. We used Excel and Epi Info 7.2.4. software for data extraction and analysis. Frequencies and proportions were calculated, and in a logistic regression, we estimated the ORs of association with their 95% confidence intervals, the factors associated with COVID-19 at the threshold of p<0.05. Of 572 notified cases of suspected COVID-19 in children aged 0-15, 11.36% were positive. The median age of infected children was 10 years [IQR: 5- 13 years]. The male/female sex ratio was 2.1. Children aged 11 to 15 accounted for 49.2%, 61.5% lived in Niamey, 4.6% had comorbidities. The notion of travel was 12.3% and 40% had a notion of contact, 24.4% had a fever, 23.2% had a cough, 18% were hospitalized, and a case-fatality rate of 1.5%. In etiological analysis, the factors associated with COVID-19 were sex ORa=0.51 [0.28-0.93] p=0.028, presence of symptoms ORa=2.29 [1.23-4.25] p=0.008 and notion of contact ORa=0.32 [0.13-0.77] p=0.011. Exposed children were sensitive to COVID-19, and all age groups were affected, with a predominance of males. We recommend barrier measures adapted to young people, and early detection and management of infected children.

[First detection of Rift Valley Fever Virus among Culex pipiens in Tahoua, Niger]. / Détection du virus de la fièvre de la vallée du Rift chez Culex pipiens à Tahoua au Niger.

Background: The Rift Valley Fever (RVF) is an arbovirus disease responsible of regular epizootics and epidemics in sub-Saharan Africa and Arabian Peninsula. In 2016, Niger experienced its first outbreak of RVF in Tahoua region, which resulted in high consequences in animal and human health. The aim of this study was to investigate on the RVFV circulation among potential vectors of the disease. Methods: This was a cross-sectional survey carried out in Tahoua and Agadez regions in August 2021. Adult mosquitoes were collected by using the morning spray in human dwellings and the CDC light trap methods. After morphological identification, viral RNA was extracted. The RNA was extracted by using QIAamp Viral RNA Mini Kit (Qiagen). The RVFV detection was performed by using the qRT-PCR method. Results: A total of 2487 insects (1978 mosquitoes, 509 sandflies and 251 biting midges) were identified and divided into three families (Culicidae, Psychodidae and Ceratopogonidae). The Culicidae family composed of the Culex genus being the most abundant with a predominance of Cx.pipiens (31.88%; n = 793) followed by Mansonia sp (21.51%; n = 535), Anophelesgambiae s.l. (8.44%; n = 210), An. pharoensis (0.72%; n = 18), An. rufipes (0.48%; n = 12), Cx. quinquefasciatus (6.39%; n = 159), the Psychodidae with sandflies (20.46%; n = 509), and the Ceratopogonidae with Culicoides genus (10.09%; n = 251). The qRT-PCR carried out on a sample of mosquitoes (N = 96) highlighted that one individual of Cx.pipiens was found positive to RVFV. This specimen was from Tassara locality (Tahoua) and collected by CDC Light Trap method. Conclusion: This study reveals for the first time the circulation of RVFV among Cx.pipiens in Niger and highlights the possible vectorial role of this vector in the disease transmission. Further investigations should be carried out to identify the biological and ecological determinants that support the maintenance of the virus in this area in order to guide control interventions.

A Fatal Case of COVID-19 in an Infant with Severe Acute Malnutrition Admitted to a Paediatric Ward in Niger.

While there have been very few fatal cases, SARS-CoV-2 has been reported in paediatric patients. This study aims to describe a fatal case of COVID-19 in a child with severe acute malnutrition. The eight-month-old child presented with fever, diarrhoea, and difficulty in breathing. The mother of the child had fever and shortness of breath four weeks before she died. Physical examination revealed lethargy, dehydration, and severe weight loss with a weight of 5 kg at a height of 78 cm tall. The weight-for-height index was less than three Z-scores, which corresponds to severe acute malnutrition. The pulmonary examination revealed moderate respiratory distress, and the chest X-ray presented features suggestive of pneumonia in the right lung area. In the context of the COVID-19 outbreak in Niger and the circumstances of the mother's death, a nasal swab was taken for laboratory confirmation. Treatment provided to the child included intranasal oxygen, antibiotics, and a dietary program with therapeutic milk. The child died 48 hours after his admission. The history of contact with a SARS-CoV-2 suspect or positive patient should lead to screening for infection by using RT-PCR. It is important to investigate malnutrition as a potential risk factor for severe SARS-CoV-2 infection and resultant mortality.

Polymorphism of PfATPase in Niger: detection of three new point mutations.

BACKGROUND: Plasmodium falciparum resistance to drugs remains a major public health issue in Niger. The therapeutic failure index for chloroquine and sulphadoxine-pyrimethamine are, respectively 20% and 21.9%. In December 2005, the National Malaria Control Programme promoted the use of artemisinin combination therapy (ACT) as first-line treatment of the uncomplicated malaria cases. Recently, studies have shown a relationship between the SERCA PfATPase6 gene and artemisinin efficacy, and pointed it out as a potential molecular marker for resistance. The goal of this work was to describe the baseline polymorphism of PfATPase6 gene in Niger, at a time when the national implementation of the ACT policy had just begun. MATERIALS AND METHODS: The DNA polymorphism of the PfATPase6 gene of 87 P. falciparum samples from Niger was analysed by sequencing. The links between the mutation occurrence and environment and human host factors were tested by bivariate analysis. RESULTS: The P. falciparum PfATPase6 gene presented polymorphisms at codons 537, 561, 569, 630, 639, 716 levels. All the mutations found were rare, except the PfATPaseN569K found in 17.2% of samples. No associated factor has been observed. CONCLUSION: The P. falciparum PfATPase gene is polymorphic at the 569 codon. As ACT is getting more and more used, the PfATPase6 gene polymorphism needs to be monitored in association with phenotypic - in vivo and/or in vitro - drug efficacy tests.

Field-based evidence of fast and global increase of Plasmodium falciparum drug-resistance by DNA-microarrays and PCR/RFLP in Niger.

BACKGROUND: Over the last years, significant progress has been made in the comprehension of the molecular mechanism of malaria resistance to drugs. Together with in vivo tests, the molecular monitoring is now part of the survey strategy of the Plasmodium sensitivity. Currently, DNA-microarray analysis allows the simultaneous study of many single nucleotide polymorphisms (SNP) of Plasmodium isolates. In December 2005, the International Federation of the Red Cross distributed two million three hundred thousand long-lasting insecticide nets to pregnant women and mothers of under five years children in the whole Niger. Then, Niger adopted artemisinin-based combination therapy as first-line treatment. METHODS: Thirty four SNPs of pfcrt, pfdhfr, pfdhps, pfmdr and pfATPase were analysed by DNA-microarray and PCR/RFLP in two villages - Zindarou and Banizoumbou - with different durations of malaria transmission. The main objective of the study was to measure the dynamics of Plasmodium falciparum resistant strains and associated factors. RESULTS: This study shows a global and clear increase of the drug-resistance associated molecular markers frequencies during a relatively short-time period of four years. Markers associated with resistance to chloroquine and sulphonamids were more frequently found in the short transmission zone than in the long transmission one. The pfcrt76T mutation is significantly more present at Banizoumbou than Zindarou (38.3% vs 25.2%, p = 0.013). This work allowed the screening of several field strains for five SNPs of PfATPase6 gene. The pfATPase6S769N, candidate mutation of resistance to artemisinin was not found. However the pfATPsaeA623E mutation was found in 4.7% of samples. CONCLUSION: A significant increase of several SNPs frequencies was highlighted over a four-year period. The polymorphism of five PfATPase6 gene SNPs was described. The global, large and fast increase of the molecular resistance is discussed in the context of current changes of health policy and malaria control in Niger.

Field-based evidence for the linkage of pfcrt and pfdhfr drug-resistant malaria genotypes and clinical profiles of severe malaria in Niger.

Drug resistance has been shown to increase malaria mortality and morbidity in both community- and hospital-based studies. We investigated the association between two Plasmodium falciparum drug resistance-related molecular markers and clinical profiles of severe malaria in children hospitalised in Niger. PCR-RFLP analysis showed that the codon 108 mutation of the pfdhfr gene was positively linked to severe malarial anaemia. These findings are consistent with persistent parasite infection leading to unbalanced anaemia in young children. No significant relationship was found between the molecular markers and hypoglycaemia or hyperparasitaemia. Conversely, the pfcrt T76 mutation was found to be negatively associated with cerebral malaria and neurological symptoms, such as convulsions and coma. These results have implications for the strain-specific virulence hypothesis and for parasite fitness and evolution. Our findings are discussed in regard to the local malaria transmission level.

[Comparison of the therapeutic efficiency and of the tolerance of the artemether-lumefantrine and artesunate-amodiaquine combination in Niger]. / Comparaison de l'efficacite therapeutique et de la tolerance des combinaisons artemether-lumefantrine et artesunate-amodiaquine au Niger.

Malaria is a major public health problem in Niger. The Global Fund to fight AIDS, Tuberculosis, and Malaria launched, in 2011, an initiative entitled "Affordable Medicines Facility - Malaria" or AMFm which aims to make artemisinin-based combination therapies (ACT) more available, more accessible and to eliminate the development of artemisinin resistance. It is in this context that we have conducted a randomized comparative double open-arm study of the efficacy and safety of artemether-lumefantrine (AL) and artesunate-amodiaquine (AM) in Gaya.The objective of the study is to evaluate and then to compare the efficiency and tolerance to these two combinations. The study was modeled with the WHO 2003, 28 days protocol.370 febrile patients were examined. 159 patients were included, where 79 (49.4%) were put in the AL arm and 81 (50.6%) were placed in the AM arm. The adequate clinical and parasitological response was 94.8% and 97.1% respectively for AL and AM. There was no statistical significant difference in efficiency between the two therapies (P=0.4). This difference in adverse effects was not statistically significant (P=0.18). Artemether-lumefantrine and artesunate-amodiaquine are two combinations with comparable efficacies and safety.

Le paludisme est un problème majeur de santé publique au Niger. Le Fonds Mondial de la lutte contre le sida, la tuberculose et le paludisme a lancé en 2011 une initiative appelée « Affordable Medecines Facility - Malaria" ou AMFm qui vise à rendre les combinaisons thérapeutiques à base d'artémisinine (CTA) plus disponibles, plus accessibles et de lutter contre la résistance à l'artémisinine. C'est dans ce contexte que nous avons mené une étude comparative, randomisée, à deux bras ouverts de l'efficacité thérapeutique des associations artémether-luméfantrine (AL) et artésunate-amodiaquine (AM) au niveau du site sentinelle de Gaya.L'objectif de l'étude est d'évaluer puis de comparer l'efficacité et la tolérance de ces deux CTA. La méthode utilisée est le protocole OMS/2003 avec le suivi de 28 jours.370 patients fébriles ont été examinés. 159 patients ont été inclus dont 79 (49.4%) pour le bras AL et 80 (50.3%) pour le bras AM. La réponse clinique et parasitologique adéquate est respectivement de 94.8% pour AL et 97.1% AM. Il n'y a pas de différence statistiquement significative d'efficacité entre les deux molécules (P=0.4). Il n'y a pas aussi de différence statistiquement significative d'effet secondaire entre les deux molécules (P=0.18). AL et AM sont d'efficacité et de tolérance comparables.

Epidemiological, clinical and biological features of malaria among children in Niamey, Niger.

BACKGROUND: Malaria takes a heavy toll in Niger, one of the world's poorest countries. Previous evaluations conducted in the context of the strategy for the Integrated Management of Childhood Illness, showed that 84% of severe malaria cases and 64 % of ordinary cases are not correctly managed. The aim of this survey was to describe epidemiological, clinical and biological features of malaria among <5 year-old children in the paediatric department of the National Hospital of Niamey, Niger's main referral hospital. METHODS: The study was performed in 2003 during the rainy season from July 25th to October 25th. Microscopic diagnosis of malaria, complete blood cell counts and measurement of glycaemia were performed in compliance with the routine procedure of the laboratory. Epidemiological data was collected through interviews with mothers. RESULTS: 256 children aged 3-60 months were included in the study. Anthropometrics and epidemiological data were typical of a very underprivileged population: 58% of the children were suffering from malnutrition and all were from poor families. Diagnosis of malaria was confirmed by microscopy in 52% of the cases. Clinical symptoms upon admission were non-specific, but there was a significant combination between a positive thick blood smear and neurological symptoms, and between a positive thick blood smear and splenomegaly. Thrombopaenia was also statistically more frequent among confirmed cases of malaria. The prevalence of severe malaria was 86%, including cases of severe anaemia among < 2 year-old children and neurological forms after 2 years of age. Overall mortality was 20% among confirmed cases and 21% among severe cases. CONCLUSIONS: The study confirmed that malaria was a major burden for the National Hospital of Niamey. Children hospitalized for malaria had an underprivileged background. Two distinctive features were the prevalence of severe malaria and a high mortality rate. Medical and non-medical underlying factors which may explain such a situation are discussed.

Low Prevalence of Pfcrt Resistance Alleles among Patients with Uncomplicated Falciparum Malaria in Niger Six Years after Chloroquine Withdrawal.

Chloroquine (CQ) resistance is widespread in Africa, but few data are available for Niger. Pfcrt haplotypes (aa 56-118) and ex vivo responses to CQ and amodiaquine were characterized for 26 isolates collected in South Niger from children under 15 years of age suffering from uncomplicated falciparum malaria, six years after the introduction of artemisinin-based combinations and the withdrawal of CQ. The wild-type Pfcrt haplotype CVMNK was found in 22 of the 26 isolates, with CVIET sequences observed in only three of the samples. We also describe for the first time a new CVINT haplotype. The ex vivo responses were better for CVMNK than for CVIET parasites. Pfcrt sequence data were compared with those obtained for 26 additional parasitized blood samples collected in Gabon, from an area of CQ resistance used as a control. Our findings suggest that there has been a significant decline in CQ-resistant genotypes since the previous estimates for Niger were obtained. No such decline in molecular resistance to CQ was observed in the subset of samples collected in similar conditions from Gabon. These results have important implications for public health and support the policy implemented in Niger since 2005, which aims to increase the efficacy and availability of antimalarial drugs whilst controlling the spread of resistance.

Controlling schistosomiasis: significant decrease of anaemia prevalence one year after a single dose of praziquantel in Nigerian schoolchildren.

BACKGROUND: In the framework of the monitoring and evaluation of the Nigerian schistosomiasis and soil-transmitted helminth control programme, a follow-up of children took place in eight sentinel sites. The objective of the study was to assess the evolution of Schistosoma haematobium infection and anaemia in schoolchildren after a single administration of praziquantel (PZQ) and albendazole. METHODS/PRINCIPAL FINDINGS: Pre-treatment examination and follow-up at one year post-treatment of schoolchildren aged 7, 8, and 11 years, including interview, urine examination, ultrasound examination of the urinary tract, and measurement of haemoglobin. Before treatment, the overall prevalence of S. heamatobium infection was 75.4% of the 1,642 enrolled children, and 21.8% of children excreted more than 50 eggs/10 ml urine. Prevalence increased with age. The overall prevalence of anaemia (haemoglobin <11.5 g/dl) was 61.6%, decreasing significantly with increasing age. The mean haemoglobinemia was 11 g/dl. In bivariate analysis, anaemia was significantly more frequent in children infected with S. haematobium, although it was not correlated to the intensity of infection. Anaemia was also associated with micro-haematuria and to kidney distensions. In a sub-sample of 636 children tested for P. falciparum infection, anaemia was significantly more frequent in malaria-infected children. In multivariate analysis, significant predictors of anaemia were P. falciparum infection, kidney distension, and the village. One year after a single-dose praziquantel treatment (administered using the WHO PZQ dose pole) co-administered with albendazole (400 mg single dose) for de-worming, the prevalence of S. haematobium infection was 38%, while the prevalence of anaemia fell to 50.4%. The mean haemoglobinemia showed a statistically significant increase of 0.39 g/dl to reach 11.4 g/dl. Anaemia was no longer associated with S. haematobium or to P. falciparum infections, or to haematuria or ultrasound abnormalities of the urinary tract. CONCLUSIONS: The high prevalence of anaemia in Nigerian children is clearly a result of many factors and not of schistosomiasis alone. Nevertheless, treatment of schistosomiasis and de-worming were followed by a partial, but significant, reduction of anaemia in schoolchildren, not explainable by any other obvious intervention.