Biology subjects

Sokhna, C.

Publications and source records attributed to Sokhna, C..

5 recordsLinked to original sources

bioRxiv2026

Continental-scale survey of Treponema pallidum in African nonhuman primates: expanding the range to the Mediterranean basin

Background: Treponema pallidum, the causative agent of yaws, bejel, and syphilis, is a significant pathogen affecting both humans and nonhuman primates (NHPs). While its presence is documented in several African NHP species, the continental-scale distribution, ecological drivers, and status in North African populations remain poorly understood. We conducted a large-scale, non-invasive survey to investigate the circulation of T. pallidum across African NHP populations and evaluate geographical and ecological patterns of exposure. Results: A total of 1,696 fecal samples from 11 wild NHP species collected across five African countries were screened for anti-T. pallidum antibodies using an automated chemiluminescent Simple Western assay, and fecal and dipteran samples were analyzed by molecular methods. Widespread seropositivity was observed across all African sites and multiple primate taxa, including great apes and cercopithecids. We provide the first evidence of T. pallidum antibodies in Barbary macaques (Macaca sylvanus) from North Africa, extending the known distribution of the pathogen to the Mediterranean basin. In West Africa, chimpanzees (Pan troglodytes verus) from Senegal and Guinea exhibited particularly high seroprevalence, confirming this region as a major endemic hotspot. In Central Africa, substantial circulation was documented in Cercopithecus wolfi, Cercopithecus ascanius, and western lowland gorillas (Gorilla gorilla gorilla). Arid/savanna biomes showed significantly higher exposure than Mediterranean and tropical rainforest biomes. No T. pallidum DNA was detected in fecal or dipteran samples. Conclusion: Our findings demonstrate widespread circulation of T. pallidum among African NHPs, reveal its presence in North African primate populations for the first time. The observed high seroprevalence, coupled with significant variations across species and geographical regions, suggests the existence of multiple transmission pathways adapted to specific host behaviors and environmental constraints. These results support the existence of a broad multihost sylvatic reservoir and provide new insights into the ecology of T. pallidum, with important implications for wildlife health, One Health surveillance, and yaws eradication efforts.

microbiology↗

bioRxiv2025

Rapid identification of Biomphalaria spp. and diagnosis of Schistosoma mansoni infestation using MALDI-TOF mass spectrometry

This study explores the use of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight mass spectrometry (MALDI-TOF MS) to identify and differentiate Biomphalaria snails infected with the parasite S. mansoni, which causes schistosomiasis. The study was conducted on two snail species, Biomphalaria pfeifferi (collected in the field in Senegal) and Biomphalaria glabrata (a laboratory strain). The snails were infected in the laboratory with S. mansoni miracidia, and their infection was confirmed by cercariae emission tests and quantitative PCR. MALDI-TOF MS was then used to analyse proteins from infected and uninfected snails to identify spectral differences. Based on protein profiles, the results of MALDI-TOF mass spectrometry made it possible to accurately differentiate between S. mansoni-infected snails and uninfected snails. An increase in the number of peaks detected and their intensity was observed for the spectra of S. mansoni-infected snails compared to uninfected snails. The application of principal component analysis to these mass spectrometry profiles confirmed the discrimination between the two groups according to their infection status. In addition, specific discriminating peaks were identified for each snail species, allowing for the distinction of infected from uninfected snails. The present study revealed, for the first time, that MALDI-TOF MS appears to be a rapid, reliable, and specific tool for the diagnosis of schistosomiasis in snails, offering promising prospects for the surveillance and control of this disease in endemic areas. However, further work is needed to establish a MALDI-TOF MS reference spectra database specific to Schistosoma parasites and to standardise sample collection, storage, and preparation in order to apply this technique in the field.

zoology↗

bioRxiv2024

Circulation of Klebsiella pneumoniae strains between the termites, chimpanzees and humans

The emergence and multiplication of multi-resistant microbes is becoming a major concern in medicine and scientific research, requiring an integrated, global approach to prevent their spread and develop new therapeutic solutions. Klebsiella pneumoniae can cause a variety of infections. It has several distinctive features, such as extended-spectrum beta-lactamase (ESBL) production and frequency in hospital-acquired infections, which set it apart from other bacteria as Pseudomonas aeruginosa or staphylococci and make it of particular concern in the clinical setting. In this study, we worked on four strains of multidrug-resistant K. pneumoniae isolated from different patients at Fann Hospital in Dakar, Senegal. Whole genomes were compared them with those of nine K. pneumoniae isolates from chimpanzees (CHZ) and six from termites (T_NSC) from our previous study. The comparison revealed two major genetic groups: three human strains were virtually identical to those found in three chimpanzees and four genomes extracted from termites regularly consumed by chimpanzees were identical to five K. pneumoniae strains from chimpanzees. In silico, we identified the resistance genes and their corresponding families from each isolate, then genotyped them before comparing them with other isolates stored in the Institute Pasteur database. These strains have never been previously identified in Senegal. It has been shown here that multiresistant K. pneumoniae strains circulate between chimpanzees and termites and between chimpanzees and humans. Furthermore, these strains, often associated with nosocomial infections, have been identified and genotyped outside Senegal. Although similar strains have been already identified in tropical countries and in different intensive care units throughout the world, we hypothesize that they may originate from termite-chimpanzee ecosystem.

bioinformatics↗

bioRxiv2022

Identification of Bulinus forskalii as a potential intermediate host of Schistosoma haematobium in Senegal

Understanding the transmission of Schistosoma haematobium in the Senegal River Delta requires knowledge of the snails serving as intermediate hosts. Accurate identification of both the snails and the infecting Schistosoma species is therefore essential. Cercarial emission tests and multi-locus (COX1 and ITS) genetic analysis were performed on Bulinus forskalii snails to confirm their susceptibility to S. haematobium infection. A total of 55 B. forskalii, adequately identified by MALDI-TOF mass spectrometry, were assessed. Cercarial shedding and RT-PCR assays detected13 (23.6%) and 17 (31.0%), respectively, B. forskalii snails parasitised by S. haematobium complex fluke. Nucleotide sequence analysis identified 6 (11.0%), using COX1, and 3 (5.5%), using ITS2, S. haematobium, and 3 (5.5%) S. bovis. This result is the first report of infection of B. forskalii by S. haematobium complex parasites.

microbiology↗

bioRxiv2018

FilmArray Respiratory Panel Integrated in a field Point Of Care dispositive for the diagnosis of respiratory tract infections in rural areas in Senegal

The development of molecular syndrome-based kits for the diagnosis of respiratory infections offers rapid and sensitive detection of common respiratory pathogens and will have a significant impact on the care of patients. In this study, we present the results obtained after the introduction of the FilmArray respiratory panel in a field Point of care (POC) for the diagnosis of virus and bacteria responsible of respiratory tract infections in Senegal rural area. From February to August 2017, we collected nasal swabs from febrile patients that presented symptoms of respiratory tract infections in three health posts located in Niakhar. Specimens were tested on site by multiplex Polymerase Chain Reaction (PCR), using the FilmArray respiratory panel(R) that targets 20 pathogens, including 17 virus and 3 bacteria (bioMerieux). Nasal swabs were collected from 113 patients. The median age was 4 years (ranging from 4 months to 60 years) and 51 (45%) were males. The prevalence of respiratory pathogens was 37.5% (12/32) during the dry season and 54.3% (44/81) in the rainy season (p=0.16). The prevalence of respiratory pathogen carriage was higher in children under 5 years of age (38/55, 69.1%). The most prevalent micro-organisms detected were influenza B virus (16/113, 14%), human rhinovirus/enterovirus (10/113, 9%), parainfluenzae virus (9/113, 8%), respiratory syncytial virus (8/113, 7%), adenovirus (5/113, 4%), human metapneumovirus (3/113, 3%), Chlamydia pneumoniae (2/113, 2%) and Coronavirus (2/113, 2%). The study has demonstrated that the integration of the FilmArray respiratory panel into a field POC could significantly improve the management of respiratory tract infections in rural areas.\n\nAuthor summaryRespiratory tract infections are one of the leading causes of death worldwide. Populations in underdeveloped countries are the most affected, especially children under 5 years of age. Among the pathogens responsible for these infections, bacteria and viruses are the most identified. In poor countries, laboratory diagnosis can only be done in urban areas. They are generally based on bacteriological, immunological or molecular biology techniques. The concept of POC is not developed in underdeveloped countries. Its existence would have made it possible to carry out RDTs to confirm the clinicians diagnosis and allow rapid management of the patient. In the current situation, the time required to achieve results is often very long for patients. In this study, we sought to demonstrate the significant contribution of the FilmArray respiratory panel in the management of respiratory tract infections in rural areas. We also wanted to reduce the time it takes to deliver results in order to improve patient care. This dispositif was integrated in a field POC which was implemented in Niakhar since 2015, in order to improve the management of emerging diseases. The FilmArray respiratory panel gave us the opportunity to investigate the causes of respiratory tract infections in this area. For each patient, we systematically target 20 pathogens, including 17 viruses and 3 bacteria, with a single multiplex PCR. One of the main results of this study is that children under 5 years of age are the most affected by respiratory tract infections. Then we noted a lack of consultation among adults that could be explained by the banalization of respiratory problems or a preference for traditional care. The fact that children under 5 years of age are the most affected could also serve as a basis for implementing vaccination programmes directly targeting the most vulnerable age groups. It should be noted that for 51% of patients, the result of the diagnosis was negative. It would appear that some pathogens responsible for respiratory tract infections are not targeted by the multiplex PCR. Thus, it would be necessary to screen these pathogens in order to integrate them into a panel that would cover the most pathogens in circulation in this area.

molecular biology↗