Biology subjects

Ranque, S.

Publications and source records attributed to Ranque, S..

6 recordsLinked to original sources

bioRxiv2026

Optimized MALDI-TOF mass spectrometry enables reliable identification of freshwater snails from schistosomiasis-endemic areas in Mauritania

Freshwater snails act as intermediate hosts for parasites affecting both humans and livestock, including schistosomes. In Mauritania, however, the diversity, distribution, and infection status of these snails remain poorly documented. This study aimed to identify freshwater snail species collected from two schistosomiasis-endemic areas in southern Mauritania, characterize their spatial distribution, and assess their infection rates using molecular tools Malacological surveys were conducted in Kankossa and Oued Rawdha during the 2023 rainy season. A total of 806 snail specimens were collected and preserved in 70% ethanol at 4 {degrees}C prior to analysis. Five species were identified morphologically and confirmed by molecular analysis: Bulinus truncatus, B. forskalii, B. senegalensis, B. umbilicatus, and Melanoides tuberculata. MALDI-TOF MS generated high-quality spectra for 99.0% of specimens and correctly identified 99.9% of analyzable samples after molecular confirmation of discrepant cases. Preservation in ethanol at 4 {degrees}C markedly improved spectral quality compared with previously reported room-temperature storage conditions Distinct ecological distributions were observed according to water body type. B. senegalensis and B. umbilicatus were exclusively collected from temporary ponds, whereas B. truncatus, B. forskalii, and M. tuberculata were found in permanent water bodies. Real-time PCR screening detected Schistosoma haematobium complex DNA in 239/798 (29.9%) specimens, with substantially higher infestation rates in Kankossa than in Oued Rawdha. These findings demonstrate that MALDI-TOF MS is a rapid, accurate, and field-compatible tool for freshwater snail identification, including closely related species that are difficult to distinguish morphologically. This approach could facilitate large-scale epidemiological surveillance and improve monitoring of schistosomiasis transmission dynamics in endemic settings.

molecular biology↗

bioRxiv2026

Quantitative polymerase chain reaction from malaria rapid diagnostic tests to detect Borrelia crocidurae in febrile patients in Mali

Tick-borne relapsing fever (TBRF) is caused by Borrelia species transmitted to humans by soft ticks of the genus Ornithodoros. Very little is currently known about the morbidity of this disease in Mali, despite the risk of human co-infection with malaria. The lack of appropriate diagnostic services or technical expertise to differentiate suspected malaria from other causes of febrile illness of unknown origin means that this tick-borne disease remains neglected and under-diagnosed in febrile patients in Mali. Our study investigated the detection of Borrelia crocidurae DNA in febrile patients in Mali from malaria rapid diagnostic tests (RDTs). MethodsBetween June and December 2021, negative and positive malaria RDTs were collected from 41 sites in the nine regions of Mali. Both qPCR and standard PCR were used to detect the presence of B. crocidurae DNA. ResultsOf the 1496 malaria RDTs tested, B. crocidurae DNA was detected in 9 malaria-negative RDTs. All of these were collected in the region of Kayes, where the prevalence rate was 6% (9/150) of the negative malaria RDTs. ConclusionsThis study demonstrates that tick-borne relapsed fever is an under-diagnosed condition in febrile patients in Mali.

molecular biology↗

bioRxiv2025

Morphological and MALDI-TOF MS identification of freshwater snails, including intermediate hosts of schistosomes in Gabon.

A thorough knowledge of intermediate snail hosts and their geographical distribution is essential to understanding the transmission of schistosomiasis and to inform interventions in Gabon. Accurate identification of both snails species and Schistosoma species is therefore essential. The aim of this study was to identify the intermediate hosts of Schistosoma spp. (snails) using MALDI-TOF MS. MethodsSnails were collected from various sites across Gabon and were morphologically identified to species or genus level. Snail species were randomly selected, dissected and subjected to MALDI-TOF MS and molecular analysis. Parasites were detected by cercarial emission, followed by qPCR analysis and sequencing. ResultsA total of 3,722 snails were collected and morphologically identified as Bulinus truncatus (n=1845), Bulinus forskalii (n=381), Gyraulus costulatus (n=680), Bellamya sp. (n=67) and Melania sp. (n=749). Of the 3,722 snails collected, 21.2% (n = 791) were selected for further analysis, including Bu. truncatus (n = 301), Bu. forskalii (n = 158), and Gy. costulatus (n=147). A subset of 65 snails was subjected to molecular identification to confirm morphological classification, using COI, ITS, and 18S gene. BLAST analysis of the resulting sequences showed 97-100% identity with reference sequences of Bu. truncatus, Bu. forskalii, and Gy. costulatus available in GenBank. Analysis of the MS spectra from the 791 snails revealed that 78.2% (n = 618) were of high quality, with signal intensities exceeding 3,000 arbitrary units (a.u.). The MALDI-TOF MS reference database was subsequently updated with 12 high-quality spectra, comprising four representative spectra for each snail species. A blind test of 606 remaining spectra against the database. A blind test of the remaining 606 spectra, using the updated MALDI-TOF MS reference database, demonstrated reliable identification of 100% (Bulinus forskalii, 147/147; Gyraulus costulatus, 158/158) and 96% (Bulinus truncatus, 289/301) of the specimens. These results were consistent with morphological identification, with log score values (LSVs) ranging from 1.7 to 2.8. Principal component analysis (PCA) showed that Bulinus species clustered according to their geographical origin. Overall, 17,66% of the snails analysed were found to be positive for Schistosoma sp. Further analysis, including qPCR and sequencing, revealed that the snails were infected with Schistosoma haematobium. ConclusionWe report the first data on the identification of snails by MALDI-TOF MS in Gabon and show that Bu. truncatus and Bu. forskalii are potential intermediate hosts of S. haematobium. We also show a heterogeneous spatiotemporal distribution of snails in south-eastern Gabon. The role of G. costulatus in the transmission of schistosome remains unclear. Author SummarySchistosomiasis is a disease caused by trematodes of the genus Schistosoma. Freshwater snails of the genera Biomphalaria, Bulinus and Oncomelania release infectious cercariae, which are transmitted to the final host (human or animal). It is the second most widespread parasitic disease after malaria, and among the most important neglected tropical diseases in the world. Snail identification is extremely important for monitoring snail populations and schistosomiasis. Identification has long relied on morphological criteria and molecular biology, both of which have several drawbacks. However, numerous studies have reported the performance of MALDI-TOF MS, a technology that allows species to be identified based on their proteins, as a reliable, rapid and easy-to-use tool in many fields. Recently, it has been described as an effective tool for snail identification and even for tracing the origin of the intermediate hosts of schistosomiasis. The objective of this study was to accurately identify freshwater snails, including the intermediate hosts of schistosomiasis in Gabon.

ecology↗

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↗

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↗

bioRxiv2019

Investigation of skin microbiota reveals Mycobacterium ulcerans-Aspergillus sp. trans-kingdom communication

BackgroundMycobacterium ulcerans secrete a series of non-ribosomal-encoded toxins known as mycolactones that are responsible for causing a disabling ulceration of the skin and subcutaneous tissues named Buruli ulcer. The disease is the sole non-contagion among the three most common mycobacterial diseases in humans. Direct contact with contaminated wetlands is a risk factor for Buruli ulcer, responsible for M. ulcerans skin carriage before transcutaneous inoculation with this opportunistic pathogen. Methodology and principal findingsIn this study, we analysed the bacterial and fungal skin microbiota in individuals exposed to M. ulcerans in Burkina Faso. We showed that M. ulcerans-specific DNA sequences were detected on the unbreached skin of 6/52 (11.5%) asymptomatic farmers living in Sindou versus 0/52 (0%) of those living in the non-endemic region of Tenkodogo. Then, we cultured the skin microbiota of asymptomatic M. ulcerans carriers and negative control individuals, all living in the region of Sindou. A total of 84 different bacterial and fungal species were isolated, 21 from M. ulcerans-negative skin samples, 31 from M. ulcerans-positive samples and 32 from both. More specifically, Actinobacteria, Aspergillus niger and Aspergillus flavus were significantly associated with M. ulcerans skin carriage. We further observed that in vitro, mycolactones induced spore germination of A. flavus, attracting the fungal network. ConclusionThese unprecedented observations suggest that interactions with fungi may modulate the outcome of M. ulcerans skin carriage, opening new venues to the understanding of Buruli ulcer pathology, prophylaxis and treatment of this still neglected tropical infection. Author summaryBuruli ulcer is a chronic infectious disease caused by the environmental opportunistic pathogen Mycobacterium ulcerans which secretes an exotoxin responsible for its pathogenicity. The reservoir and sources of M. ulcerans in the environment remain elusive and its mode of transmission is unclear. To acquire M. ulcerans infection, at least two conditions must be met, viable bacteria and a skin lesion as demonstrated by experimental animal models. In this study, we showed that M. ulcerans specific DNA sequences could be detected on the healthy skin of asymptomatic farmers living in one region of Burkina Faso where Buruli ulcer cases had already been reported, but not in Buruli ulcer-free regions, suggesting skin carriage after contacts with environmental sources. We also investigated the skin microbiota of M. ulcerans carriers and found significant associations of some bacteria and fungi with skin carriage of M. ulcerans. These associations may due to the effect of mycolactones on some fungi species. As we showed previously with Mucor circinelloides and here with Aspergillus flavus.

microbiology↗