Epidemiology of bacterial resistance at the Grand Magal of Touba in Senegal.

BACKGROUND: The Grand Magal of Touba (GMT) associates with risks of infection, but no study on the circulation of resistant bacteria has yet been conducted. MATERIALS AND METHODS: qPCR was performed on rectal samples from GMT pilgrims between 2018 and 2021, before and after their participation in the gathering. Rectal samples from between 2018 and 2020 were also cultured on specific media, and antibiotic susceptibility testing was performed. RESULTS: Forty-one of the 296 (13.8%) pilgrims had at least one gastrointestinal symptom and 91/290 (31.4%) acquired pathogenic bacteria, mostly Escherichia coli. A total of 54.7% of pilgrims reported washing their hands more frequently than usual and 89.2% used soap. One hundred and five (36.2%) acquired at least one resistance gene, notably CTX-M A (21.0%), SHV (16.5%) and TEM (8.2%). The strains isolated by culture were mostly E. coli. These bacteria were found to be sensitive to carbapenems and resistant to amoxicillin and amoxicillin-clavulanic acid. The acquisition of enteroaggregative E. coli was independently associated with CTX-M A and TEM acquisition. CONCLUSION: Pilgrims presented a risk for acquisition of CTX-M A after the GMT. Surveillance of the prevalence of resistant bacteria and the occurrence of associated clinical infections among pilgrims are necessary in the future.

Influenza at the 2021 Grand Magal of Touba and possible spread to rural villages in South Senegal - a genomic epidemiological study.

OBJECTIVES: Influenza is frequent among pilgrims participating in the Grand Magal de Touba (GMT), in Senegal, with a potential to spread to contacts when they return home. METHODS: Ill pilgrims consulting at a health care center in Mbacké city close to Touba during the 2021 GMT, pilgrims returning to Dielmo and Ndiop villages, and patients who did not travel to Touba and consulted at health care centers in these two villages in 2021 were tested for the influenza virus by polymerase chain reaction on nasopharyngeal samples. Next-generation sequencing and comparative and phylogenetic analyses of influenza A virus genomes were performed. RESULTS: A total of 62 of 685 patients tested positive for influenza A virus, including 34 of 53 who were consulted in Mbacké in late September, six of 129 pilgrims who returned home in early October, and 20 of 42 villagers from October 3 to 29. A total of 27 genomes were obtained. Four clusters were observed based on the phylogenetic analyses, suggesting that Mbacké patients and returned pilgrims may have shared closely related viral strains with patients inhabiting the villages who did not participate in the GMT. CONCLUSIONS: Villagers in Ndiop and Dielmo may have been infected with viral strains originating from the GMT and possibly imported by pilgrims who returned from the GMT.

Viral and bacterial microorganisms in Vietnamese children with severe and non-severe pneumonia.

To investigate potential respiratory pathogens in children with community-acquired pneumonia (CAP) and risk factors for severe disease. This prospective study was conducted among 467 children at the Thai Binh Paediatric Hospital, Vietnam between 1 July 2020 and 30 June 2021. Clinical data and laboratory results were collected. Twenty-four respiratory microorganisms were tested from nasopharyngeal swabs using real-time PCR. Logistical regression was used to estimate a factor's adjusted odd ratios of the severity of disease. Mean age of patients = 15.4 ± 13.3 months, 63.0% were male. Over 97% of patients had a positive PCR result. 87% of patients were positive for multiple (up to eight) microorganisms. Rhinovirus (46%), respiratory syncytial virus (RSV) (24%), enterovirus (17%), and parainfluenza viruses-3 (13%) were the most frequent viruses. H. influenzae (61%), S. pneumoniae (45%) and M. catarrhalis (30%) were the most common bacteria. 128 (27%) cases were classified as severe pneumonia. Presence of smokers at home (aOR 2.11, 95% CI 1.27-3.52, P value = 0.004), CRP level ≥ 50 mg/dL (aOR 6.11, 95% CI 3.86-9.68, P value < 0.0001), RSV (aOR 1.78, 95% CI 1.07-2.96, P value = 0.03) and H. influenzae (aOR 1.66, 95% CI 1.03-2.67, P value = 0.04) PCR detection associated with a higher risk of severe pneumonia; ,. Causative agents of pneumonia in children are complex. Children positive with RSV and H. influenzae need to be closely monitored to prevent severe pneumonia.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry traces the geographical source of Biomphalaria pfeifferi and Bulinus forskalii, involved in schistosomiasis transmission.

BACKGROUND: Freshwater snails of the genera Bulinus spp., Biomphalaria spp., and Oncomelania spp. are the main intermediate hosts of human and animal schistosomiasis. Identification of these snails has long been based on morphological and/or genomic criteria, which have their limitations. These limitations include a lack of precision for the morphological tool and cost and time for the DNA-based approach. Recently, Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI-TOF) mass spectrometry, a new tool used which is routinely in clinical microbiology, has emerged in the field of malacology for the identification of freshwater snails. This study aimed to evaluate the ability of MALDI-TOF MS to identify Biomphalaria pfeifferi and Bulinus forskalii snail populations according to their geographical origin. METHODS: This study was conducted on 101 Bi. pfeifferi and 81 Bu. forskalii snails collected in three distinct geographical areas of Senegal (the North-East, South-East and central part of the country), and supplemented with wild and laboratory strains. Specimens which had previously been morphologically described were identified by MALDI-TOF MS [identification log score values (LSV) ≥ 1.7], after an initial blind test using the pre-existing database. After DNA-based identification, new reference spectra of Bi. pfeifferi (n = 10) and Bu. forskalii (n = 5) from the geographical areas were added to the MALDI-TOF spectral database. The final blind test against this updated database was performed to assess identification at the geographic source level. RESULTS: MALDI-TOF MS correctly identified 92.1% of 101 Bi. pfeifferi snails and 98.8% of 81 Bu. forskalii snails. At the final blind test, 88% of 166 specimens were correctly identified according to both their species and sampling site, with LSVs ranging from 1.74 to 2.70. The geographical source was adequately identified in 90.1% of 91 Bi. pfeifferi and 85.3% of 75 Bu. forskalii samples. CONCLUSIONS: Our findings demonstrate that MALDI-TOF MS can identify and differentiate snail populations according to geographical origin. It outperforms the current DNA-based approaches in discriminating laboratory from wild strains. This inexpensive high-throughput approach is likely to further revolutionise epidemiological studies in areas which are endemic for schistosomiasis.

Influence of Microbiota on Clinical Expressions of Respiratory Viral Infections.

Respiratory infections, mainly due to viruses, are among the leading causes of worldwide morbidity and mortality. We investigated the prevalence of viruses and bacteria in a cross-sectional survey conducted in Dielmo, a village in rural Senegal with a population of 481 inhabitants. Nasopharyngeal sampling was performed in 50 symptomatic subjects and 101 asymptomatic subjects. Symptomatic subjects were defined as individuals presenting with clinical signs of respiratory infection, whereas asymptomatic subjects were recruited in the same households. The identification of pathogens was performed by polymerase chain reaction for 18 respiratory viruses and eight respiratory bacteria. The prevalence results for respiratory viruses detected in each study group demonstrated that 83.6% of symptomatic samples were positive for at least one respiratory virus, and 21.8% were detected in asymptomatic samples. Influenza A (P = 0.0001), metapneumovirus (P = 0.04), and enterovirus (P = 0.001) were significantly more prevalent in symptomatic patients. Overall, 82.0% of symptomatic subjects and 26.9% of asymptomatic subjects were positive for at least one respiratory bacterium. The most frequent pathogenic bacteria detected were Moraxella catarrhalis (56%) and Streptococcus pneumoniae (48.0%) among symptomatic individuals, whereas in asymptomatic subjects Corynebacterium propinquum was more prevalent (18%). A principal component analysis showed that parainfluenzas 2 and 4 were associated with asymptomatic subjects, whereas influenza A was associated with the presence of symptoms. Considering these results, a large epidemiological surveillance of the circulation of these respiratory pathogens in the general population should be conducted to provide a better understanding of their carriage and to potentially prevent epidemics.

Molecular diagnosis of urogenital schistosomiasis in pre-school children, school-aged children and women of reproductive age at community level in central Senegal.

BACKGROUND: Urogenital schistosomiasis is a major public health concern in sub-Saharan Africa. In Senegal, the disease is endemic in all regions of the country. Recently, WHO strongly recommended including pre-school children and women of reproductive age during a mass drug administration campaign. It is important to describe the burden of the disease in these group at risk using innovative diagnostic tools. This study aimed to assess the use of real-time PCR in the detection of schistosomiasis cases at the community level in a seasonal transmission area. METHODS: A cross-sectional survey was carried out in Niakhar located in the centre of Senegal. Pre-schoolchildren, school-aged children and female adolescents and adults were invited to participate in the study in April 2018. Urine samples were collected and examined using Hemastix reagent strips, filtration technique and real-time PCR. Schistosoma haematobium was detected, identified by targeting the Dra1 gene. The prevalence of urogenital schistosomiasis was determined for each group and the performance of the real-time PCR was compared with the conventional techniques. RESULTS: A total of 428 participants were enrolled in this study including 87 (20.4%) pre-school children (1-5 years), 262 (61.3%) school-aged children between (5-14 years), 17 (3.9%) adolescents (15-17 years) and 62 (14.4%) female adults. The comparison of the diagnostic techniques has shown that the prevalence of urogenital schistosomiasis is higher using molecular technique (34.6%) compared to microscopy (20.3%). The percentage rate of haematuria using Hemastix was 23.1%. School-aged children between 5 and 14 years old were the most affected with 29.0% and 43.1% under microscopy and RT-PCR, respectively. In female participants, microscopic prevalence decreases with age, from 21.4% in school-aged children to 17.6% in adolescents and 9.7% in adults. There was good correlation between the number of eggs per 10 ml and the cycle threshold range. CONCLUSION: These results show the importance of using molecular tools in the surveillance of schistosomiasis particularly in pre-school children and women of reproductive age.

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.

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.

Epidemiological Investigations of Infectious Diseases among Mobile Populations at the University Hospital Institute Mediterranean Infection in Marseille, France.

We review the most recent work conducted by our group on the circulation of infectious agents in mobile populations, including pilgrims participating in the Hajj (Mecca, Saudi Arabia) and the Grand Magal of Touba (Senegal) pilgrimages, homeless people, and medical students participating in an elective abroad. Using a similar epidemiological study design with standardized questionnaires and molecular assays allows comparison of different populations of travelers. The main infectious pathogens and antibiotic resistance genes linked to travel were identified in certain specific populations of travelers, as well as in a group of homeless migrant people in Marseille. The role of several risk factors has also been demonstrated, allowing identifying individuals at increased risk of disease or pathogen carriage on which to base targeted preventive measures. Such results, together with those obtained through international surveillance networks allow better description of the epidemiology of travel-associated infectious diseases.

Bulinus senegalensis and Bulinus umbilicatus Snail Infestations by the Schistosoma haematobium Group in Niakhar, Senegal.

Thorough knowledge of the dynamics of Bulinus spp. infestation could help to control the spread of schistosomiasis. This study describes the spatio-temporal dynamics of B. senegalensis and B. umbilicatus infestation by the Schistosoma haematobium group of blood flukes in Niakhar, Senegal. Molecular identification of the S. haematobium group was performed by real-time PCR, targeting the Dra 1 gene in 810 samples of Bulinus spp. collected during the schistosomiasis transmission season in 2013. In addition to Dra 1 PCR, a rapid diagnostic-PCR was performed on a sub-group of 43 snails to discriminate S. haematobium, S. bovis, and S. mattheei. Out of 810 snails, 236 (29.1%) were positive for Dra 1 based on the PCR, including 96.2% and 3.8% of B. senegalensis and B. umbilicatus, respectively. Among the sub-group, 16 samples were confirmed to be S. haematobium while one was identified as a mixture of S. haematobium and S. bovis. Snails infestations were detected in all villages sampled and infestation rates ranged from 15.38% to 42.11%. The prevalence of infestation was higher in the north (33.47%) compared to the south (25.74%). Snail populations infestations appear early in the rainy season, with a peak in the middle of the season, and then a decline towards the end of the rainy season. Molecular techniques showed, for the first time, the presence of S. bovis in the Bulinus spp. population of Niakhar. The heterogeneity of snail infestations at the village level must be taken into account in mass treatment strategies. Further studies should help to improve the characterizations of the schistosome population.

Respiratory infections among pilgrims at the Grand Magal of Touba: A comparative cohort controlled survey.

BACKGROUND: The Grand Magal of Touba (GMT) is a large event gathering around 4-5 million participants every year. A pilot study conducted in 2017 among GMT pilgrims showed that 41.8% of participants reported respiratory symptoms, mostly due to rhinovirus (13.0%), coronaviruses (16.0%) and adenovirus (4.6%). METHODS: A PCR-based prospective cohort study was conducted among GMT pilgrims and controls (who did not participate to the event) in two rural villages in South Senegal, in 2019. RESULTS: 93 pilgrims and 84 controls were included in the study. There were no significant differences between pilgrims and controls regarding demographic characteristics and chronic conditions. 60.2% of pilgrims reported respiratory symptoms during their stay in Touba, or soon after their return. By contrast, only 8.3% of controls reported respiratory symptoms after the GMT. The acquisition of rhinovirus, coronaviruses, Streptococcus pneumoniae and Moraxella catarrhalis was 22.6%, 6.5%, 17.2% and 6.8% respectively in pilgrims and was significantly higher than in controls (3.6%, 0%, 4.8% and 1.2% respectively). Respiratory symptoms post-GMT were five times more frequent in S. pneumoniae carriers (aOR = 5.18, 95%CI = [1.98-13.57]). CONCLUSION: This study demonstrates that individuals who participated in the GMT were at higher risk of suffering from respiratory symptoms and that this was linked to the acquisition of S. pneumoniae.

Screening Strategy of Active Pulmonary Tuberculosis in Sheltered Homeless People in Marseille, 2019.

We aimed to assess the reliability of a screening questionnaire for Active Pulmonary Tuberculosis (APTB) in a population of sheltered homeless persons (HP). Participants from two homeless shelters completed a questionnaire specially designed to identify patients at high-risk of APTB (available at www.tb-screen.ch), underwent a Chest X-ray (CXR), and provided sputum samples. Computed Tomography (CT) scanning was subsequently performed on those which had images consistent with APTB. Microscopical examination, real-time polymerase chain reaction (qPCR) and culture testing were applied for Mycobacterium tuberculosis complex detection. Additionally, we retrospectively selected 16 HP hospitalised in our hospital between 2017 and 2019 with biologically confirmed tuberculosis and typical CXR images, and retrospectively documented a screening questionnaire by reviewing their medical files. Overall, the population (n = 383 HP) was predominantly migrants (87%). Forty-seven individuals (11.7%) had positive screening questionnaire scores and four (2.4%) displayed abnormal CXR features consistent with APTB. Three of them three underwent CT scanning that ruled out APTB and one was lost to follow-up. None tested positive through microbiological investigation. Fifteen (of 16, 93.8%) hospitalised patients with biologically confirmed APTB had a positive screening questionnaire score. The sensitivity and specificity of questionnaire for confirmed APTB were 93.8% and 87.7%, respectively. Screening questionnaires can be used as a first assessment tool in people arriving at homeless shelters and to refer those screening positive for a CXR.

Screening of SARS-CoV-2 among homeless people, asylum-seekers and other people living in precarious conditions in Marseille, France, March-April 2020.

BACKGROUND: Surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among sheltered homeless and other vulnerable people might provide the information needed to prevent its spread within accommodation centres. METHODS: Data were obtained from 698 participants in different accommodation centres (411 homeless individuals, 77 asylum-seekers, 58 other people living in precarious conditions and 152 employees working in these accommodation centres) who completed questionnaires and had nasal samples collected between 26 March and 17 April 2020. SARS-CoV-2 carriage was assessed by quantitative PCR. RESULTS: We found a high acceptance rate (78.9%) for testing. Overall, 49 people (7.0%) were positive for SARS-CoV-2, including 37 homeless individuals (of 411, 9.0%) and 12 employees (of 152, 7.9%). SARS-CoV-2 positivity correlated with symptoms, although 51% of patients who tested positive did not report respiratory symptoms or fever. Among homeless people, being young (18-34 years) (odds ratio 3.83, 95% confidence interval 1.47-10.0, p = 0.006) and being housed in one specific shelter (odds ratio 9.13, 95% confidence interval 4.09-20.37, p < 0.001) were independent factors associated with SARS-CoV-2 positivity (rates of 11.4% and 20.6%, respectively). DISCUSSION: Symptom screening alone is insufficient to prevent SARS-CoV-2 transmission in vulnerable sheltered people. Systematic testing should be promoted.

Variations in respiratory pathogen carriage among a homeless population in a shelter for men in Marseille, France, March-July 2020: cross-sectional 1-day surveys.

We aimed to compare respiratory pathogen carriage by PCR during three different time periods in 2020 in sheltered homeless people in Marseille, France. The overall prevalence of respiratory pathogen carriage in late March-early April (69.9%) was significantly higher than in late April (42.3%) and mid-July (45.1%). Bacterial carriage significantly decreased between late March-early April and late April. SARS-CoV-2 was detected only in late March-early April samples (20.6%). Measures aiming at mitigating SARS-CoV-2 transmission were effective and also impacted bacterial carriage. Seasonal variations of bacterial carriage between winter and summer in this population were not marked.

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.