PCR investigation of infections in patients consulting at a healthcare centre over a four-year period during the Grand Magal of Touba.

BACKGROUND: Respiratory and gastrointestinal symptoms and febrile illness are the most common complaints among ill pilgrims attending the Grand Magal of Touba (GMT) in Senegal. METHODS: Patients presenting with respiratory or gastrointestinal symptoms or febrile systemic illnesses were recruited between 2018 and 2021 at a healthcare centre close to Touba. Respiratory, gastrointestinal and blood samples were tested for potential pathogens using qPCR. RESULTS: 538 patients were included. 45.5% of these were female, with a median age of 17 years. Of the 326 samples collected from patients with a cough, 62.8% tested positive for at least one virus, including influenza viruses (33.1%). A high positivity rate of bacterial carriage was observed for Haemophilus influenzae (72.7%), Streptococcus pneumoniae (51.2%) and Moraxella catarrhalis (46.0%). Of the 95 samples collected from patients with diarrhoea, 71.3% were positive, with high rates of bacterial carriage, ranging from 4.2% for Tropheryma whipplei to 45.3% for Entero-pathogenic Escherichia coli. Of the 141 blood samples collected from patients with fever, 31.9% were positive including Plasmodium falciparum (21.3%), Borrelia sp. (5.7%) and dengue virus (5.0%). CONCLUSION: This study provides insight into the aetiology of most common infections at the GMT on which to base therapeutic options.

Evolution of SARS-CoV-2 Strains in Senegal: From a Wild Wuhan Strain to the Omicron Variant

The coronavirus disease 2019 (COVID-19) is a contagious disease caused by a new coronavirus called SARS-CoV-2. The first case was discovered in Wuhan, China, in December 2019, raising concerns about the emergence of a new coronavirus that poses a significant public health risk. The objective of this study, based on data collected and sequenced at the Institut de Recherche en Santé, de Surveillance Epidémiologique et de Formations (IRESSEF), is to characterize the pandemic evolution, establish a relationship between the different strains in each wave, and finally determine the phylodynamic evolution of the pandemic, utilizing microreact simulations. The study shows that SARS-CoV-2 strains have evolved over time and the variability of the virus is characterized by sequencing during each wave, as is its contagiousness (the speed at which it spreads). The pandemic has spread at a rate of 44.34 cases/week during the first wave. Twelve weeks later it has risen to 185.33 cases/week during the second wave. Twenty-three weeks into the pandemic, the numbers have reached 681.77 cases/week during the third wave. During the fourth wave, the rate of infection was found to decrease slightly at 646 cases/week between early December 2021 and mid-January 2022. Data collected during this study also provided us with a geographical distribution of COVID-19, indicating that the epidemic started in Dakar before spreading inland.

Risk factors for symptoms of infection and the acquisition of pathogens among pilgrims at the Grand Magal of Touba, 2017-2021.

BACKGROUND: Respiratory and gastrointestinal symptoms are frequent in pilgrims at the Grand Magal of Touba (GMT). METHODS: Pilgrims were prospectively investigated in 2017-2021 for demographics, chronic conditions, preventive measures, respiratory and gastrointestinal symptoms, and pathogen carriage using PCR assays. RESULTS: 535 pilgrims were included. 54.8% and 13.3% reported respiratory and gastrointestinal symptoms, respectively. 18.4% acquired respiratory viruses, notably rhinovirus (10.1%) and coronaviruses (5.6%) and 39.9% bacteria, notably Haemophilus influenzae (18.9%) and Streptococcus pneumoniae (14.1%). The acquisition of gastrointestinal pathogens was lower, with enteroaggregative Escherichia coli (18.9%) and enteropathogenic Escherichia coli (10.5%) being the most frequent. A decrease was observed in the acquisition rates of pathogens in 2020-2021 GMT. Female pilgrims were more at risk of respiratory and gastrointestinal symptoms. Respiratory symptoms were associated with virus acquisition (aRR: 2.20, 95%CI [1.38-3.50]) and S. pneumoniae acquisition (aRR: 2.76, 95%CI = [1.64-4.62]). Using hand soap was associated with a decrease in the acquisition of rhinovirus (aRR: 0.42, 95%CI [0.22-0.80]) and coronavirus (aRR: 0.42, 95%CI [0.22-0.81]). Using face masks was associated with a decrease in reporting of respiratory symptoms (aRR: 0.54, 95% [0.35-0.86]). CONCLUSION: Hand washing with soap and wearing face masks should be recommended to GMT pilgrims.

Heterogeneity of the Omicron variant in Senegal.

•Omicron variant continues to progress in Senegal with the appearance of new contaminations.•IRESSEF detected the first positive case of the Omicron variant on Friday, December 3, 2021.•Since this date, the number of Omicron variant infections has increased over the weeks.•Molecular surveillance of the Omicron variant allowed us to identify a strong variation of this variant in our country.

Dynamics of Variants of Concern (VOC) of SARS-CoV-2 during the Different Waves of COVID-19 in Senegal

Background: In Senegal, the incidence of SARS-CoV-2 evolved with four successive epidemic waves. The first wave started in March 2020 with low virus variability, whilst the second outbreak, which started in December 2020, was dominated by the Alpha variant. The third wave took place in June 2021, and the fourth at the end of November 2021. Our interest was to investigate the involvement of variants of concern during these four waves and to track the viral diversity of SARS-CoV-2. Methodology: During the four waves of the pandemic, 276,876 nasopharyngeal swabs were analyzed at the Institut de Recherche en Santé, de Surveillance Epidémiologique et de Formation (IRESSEF). Of these, 22,558 samples tested positive for SARS-CoV-2 by RT-PCR. Then, the virus genomes were sequenced in 817 positive samples using the ARTIC Network of Oxford Nanopore Technologies (ONT). In addition, 10% of the negative samples in RT-PCR new variants were also targeted for the detection of new and previously undescribed variants. Results: Our data have overall shown that the Senegalese strains are very similar to each other or closely related to other strains, such as Gambia, France etc. During the first wave, the most common clade found was 19A (67.5%) and a majority of the samples were of the B.1 (50%) lineage. We noted more diversity during the second wave where clade 20A (38.4%) was more frequent, followed by clade 20B (31.52%) and 20I (9.74%). At the level of lineages, we identified variants of concern as B.1.1.7 (9.74%) and B.1.617.2 (0.86%). In the third wave, we observed at the clade level with mainly 21A (32.63%) and 21J (16.84%). During the fourth wave at the end of November 2021, we mainly identified clade 21K Omicron variant 21K (B.1.1.529 and BA.1) (80.47%) and Delta variant (21A, 21J, and 21I) (AY.103, AY.122, AY.122.1, AY.26, AY.34, AY.36, AY.4, AY.48, AY.57, AY.61, and AY.87) (14.06%). Impact: SARS-CoV-2 diversity may affect the virus's properties, such as how it spreads, disease severity, or the performance of vaccines, tools, or other public health and social measures. Therefore, such tracking of SARS-CoV-2 variants is not only of public interest, but also highlights the role some African institutes such as IRESSEF with surveillance capabilities through the real-time sequencing of SARS-CoV-2 genomes in the local context. Conclusion: In Senegal, the SARS-CoV-2 pandemic has disrupted the organization of the health system. IRESSEF contributed to put in place strategies to respond effectively to the expectations of medical authorities by providing them with data on the strains circulating in Senegal at each moment of the epidemic.

COVID-19-related attitudes, risk perceptions, preventive behaviours and economic impact in sub-Saharan African countries: implementing a longitudinal phone-based survey protocol in rural Senegalese households.

INTRODUCTION: Rural areas are considered safe havens against the increased spread of COVID-19 and associated restrictive measures, especially in contexts where public authorities are not in a position to systematically and substantially ease COVID-19-induced economic shocks. In the current sub-Saharan Africa context, still marked by uncertainty surrounding the spread of COVID-19, we present the protocol of an ongoing longitudinal study aimed at investigating COVID-19-related attitudes, risks perceptions, preventive behaviours and economic impact in rural areas in Senegal. METHODS AND ANALYSIS: A prospective randomised longitudinal study of 600 households located in three semiurban villages and nine randomly selected rural villages in the Niakhar area (located 135 km East of Dakar). Three ad hoc phone surveys are administered to 600 heads of households, their housewives in charge of managing the household and a relative living temporarily in the household, respectively. In addition to sharing identical sets of questions on several topics (risks perceptions, attitudes to curfew, attitudes to vaccines, beliefs about COVID-19 infection), the three separate survey questionnaires also include other topics (economic impact, local preventive strategies) whose related questions differ between questionnaires. As analysing evolutions is the study's primary focus, data on all the topics covered will be collected in three waves unless the spread of COVID-19 by mid-2021 justifies extending data collection. The present article presents the study protocol and details about the implementation of the first wave of data collection which started in July 2020. The decision to wait before presenting the protocol was based on the unprecedented context the COVID-19 pandemic. ETHICS AND DISSEMINATION: The survey's protocol was approved by the Senegalese National Ethical Committee for Research in Health (131/MSAS/CNERS/Sec) and received authorisation from both the Senegalese Ministry of Health (619/MSAS/DPRS/DR) and the French Commission on Information Technology and Liberties (CNIL 2220771).

Implementation of an in-house real-time reverse transcription-PCR assay for the rapid detection of the SARS-CoV-2 Marseille-4 variant.

INTRODUCTION: The SARS-CoV-2 pandemic has been associated with the occurrence since summer 2020 of several viral variants that overlapped or succeeded each other in time. Those of current concern harbor mutations within the spike receptor binding domain (RBD) that may be associated with viral escape to immune responses. In our geographical area a viral variant we named Marseille-4 harbors a S477 N substitution in this RBD. MATERIALS AND METHODS: We aimed to implement an in-house one-step real-time reverse transcription-PCR (qPCR) assay with a hydrolysis probe that specifically detects the SARS-CoV-2 Marseille-4 variant. RESULTS: All 6 cDNA samples from Marseille-4 variant strains identified in our institute by genome next-generation sequencing (NGS) tested positive using our Marseille-4 specific qPCR, whereas all 32 cDNA samples from other variants tested negative. In addition, 39/42 (93 %) respiratory samples identified by NGS as containing a Marseille-4 variant strain and 0/26 samples identified as containing non-Marseille-4 variant strains were positive. Finally, 2018/3960 (51%) patients SARS-CoV-2-diagnosed in our institute, 10/277 (3.6 %) respiratory samples collected in Algeria, and none of 207 respiratory samples collected in Senegal, Morocco, or Lebanon tested positive using our Marseille-4 specific qPCR. DISCUSSION: Our in-house qPCR system was found reliable to detect specifically the Marseille-4 variant and allowed estimating it is involved in about half of our SARS-CoV-2 diagnoses since December 2020. Such approach allows the real-time surveillance of SARS-CoV-2 variants, which is warranted to monitor and assess their epidemiological and clinical characterics based on comprehensive sets of data.

The Grand Magal of Touba was spared by the COVID-19 pandemic.

In the context of the coronavirus disease-2019 (COVID-19) pandemic, all mass gathering (MG) events have been cancelled. The Grand Magal took place on October 6, 2020, in Touba, Senegal, which was the only MG event organized in 2020. This Muslim pilgrimage gathers about four million Muslim Mourides from Senegal and beyond. No significant increase in COVID-19 cases was therefore observed at the national level in the weeks following the Grand Magal. This successful strategy is an invitation to better promote community commitments by public authorities in their various strategies.

Establishing Medical Coverage and Epidemiological Surveillance during the Grand Magal of Touba in Senegal: A Public Health Need.

The Grand Magal is a religious pilgrimage that takes place in Senegal. An estimated 4-5 million individuals yearly gather in the holy city of Touba. Pilgrims comes from the whole Senegal and surrounding countries and from countries outside of Africa where Mouride Senegalese emigrated. It is the largest Mass Gathering (MG) event of the Mouride community and the largest Muslim religious MG in West Africa. The context of the Grand Magal MG is unique given its location in a tropical developing country and its international component which may favour the globalization of local endemic diseases and warrants investment in modern methods for public health surveillance and planning of the event.