Investigation of potentially pathogenic Vibrionaceae in Saint-Louis city, Senegal.

Introduction: as cholera, due to toxigenic bacteria Vibrio cholera (serogroups O1 and O139), is a major public health threat in Africa, the aim of this work was to investigate potentially pathogenic Vibrionaceae bacteria firstly from human stool samples, and secondly from various environmental water points of Saint-Louis city in Senegal. Methods: a hospital-based study was conducted between 2013 and 2015. Stool samples were taken and cultured from daily incoming patients or hospitalized for acute diarrhea at Saint-Louis´ regional hospital. For environment, a monthly longitudinal sampling from January to October 2016 was carried out at 10 sites in the city. We used total DNA extracted from APW (alkaline peptone water) broth solutions and on suspect bacterial colonies to run PCR Multiplex targeting specific DNA fragments to detect Vibrio genus and specific species. In case of positivity, a simplex PCR was performed to test for cholera toxins Ctx, and V. parahaemolyticus TRH and TDH. Results: for 43 patients screened, bacterial culture was positive in 6% of cases but no strain of V. cholerae or other Vibrio sp. was isolated. PCR on 90 APW solutions were positive for Vibrio sp.(n = 43), V. cholera(n = 27), V. mimicus(n = 16), V. parahaemolyticus(8), V. alginolyticus(n = 4), and V. vulnificus(n = 2). Unlike for those on suspected colonies which were positive for a majority of V. parahaemolyticus (n = 40) and V. cholerae non-O1 / O139 (n = 35). Six strains of V. parahaemolyticus carried TRH gene, 3 of which expressed simultaneously virulence TRH and TDH genes. For physicochemical parameters, all temperatures varied similarly according to a unimodal seasonality, as well as salinity. Conclusion: despite the presence of natural populations of Vibrionaceae, even toxigenic ones, was noted in water environment, along with favorable habitat conditions that could play a role in transmission of Vibriosis in the Saint Louis population, we did not isolate any of them from patients screened at the hospital.

Epidemiological and genetic characterization of multidrug-resistant non-O1 and non-O139 Vibrio cholerae from food in southern China.

This study reports a comprehensive epidemiological and genetic analysis of V. cholerae strains, specifically non-O1/non-O139 serogroups, isolated from animal-derived food samples in Guangdong province from 2015 to 2019. A total of 21 V. cholerae strains were obtained, which exhibited high resistance rates for nalidixic acid (57.14 %, 12/21), ampicillin (33.33 %, 7/21), and ciprofloxacin (19.05 %, 4/21). The quinolone resistance-related gene, qnrVC, was prevalent in 80.95 % (17/21) of the isolates. Additionally, chromosomally mediated quinolone-resistance mutations, including mutations in GyrA at position 83 (S83I) and ParC at position 85 (S85L), were detected in 47.62 % of the isolates. The combination of target mutation and qnrVC genes was shown to mediate resistance or intermediate resistance to ciprofloxacin in V. cholerae. Furthermore, an IncC-type conjugative plasmid carrying thirteen antibiotic resistance genes, including genes conferring resistance to two clinically important antibiotics, cephalosporins and fluoroquinolones, was identified in the shrimp-derived strain Vc516. While none of our food isolates harbored the toxigenic CTX- and TCP-encoding genes, they did possess genes encoding toxins such as HlyA and Autoinducer-2. Notably, some V. cholerae strains from this study exhibited a close genetic relationship with clinical strains, suggesting their potential to cause human infections. Taken together, this study provides a comprehensive view of the epidemiological features and genetic basis of antimicrobial resistance and virulence potential of V. cholerae strains isolated from food in southern China, thereby advancing our understanding of this important pathogen.

Vibrio cholerae and Salmonella Typhi culture-based wastewater or non-sewered sanitation surveillance in a resource-limited region.

BACKGROUND: In resource-limited regions, relying on individual clinical results to monitor community diseases is sometimes not possible. Establishing wastewater and non-sewered sanitation surveillance systems can offer opportunities to improve community health. OBJECTIVE: We provide our experience of establishing a wastewater and non-sewered sanitation surveillance laboratory in Malawi, a resource-limited region, for Vibrio cholerae and Salmonella serotype Typhi. METHODS: Three locations (inclusive of 8 discrete sample collection sites in total) in the Blantyre District were studied for nine weeks, from September 6 to November 1, 2022. Grab samples were collected weekly. We piloted locally available culture-based medical diagnostic methods for V. cholerae and S. Typhi in wastewater, followed by confirmation analysis of the isolates using reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Bacterial counts ranged from up to 106 colony-forming units/mL for V. cholerae and up to 107 colony-forming units/mL for S. Typhi. RT-PCR of the isolates showed that the available culture-based medical diagnostic methods were successful in detecting V. cholerae but were less accurate for S. Typhi in wastewater. IMPACT STATEMENT: This experience serves as a catalyst for the development and validation of alternative wastewater surveillance analytical methods that are not dependent solely on RT-PCR. In this field trial conducted in Africa, new data-driven approaches were developed to promote early-level wastewater research and expand analysis options in resource-limited settings. Although culture-based methods are labor-intensive and have some limitations, we suggest initially leveraging the overlap with the locally available medical testing capacity for V. cholerae, whereas S. Typhi with RT-PCR may still be required. Wastewater analysis may be acceptable for V. cholerae and S. Typhi, which have a high degree of clinical case underreporting, fecal shedding, short incubation periods, and clear outbreak trends, predominantly in low- and middle-income countries.

Pufferfish (Tetraodon cutcutia) Sampled from a Freshwater River Serves as an Intermediate Reservoir of a Sucrose Nonfermenting Variant of Vibrio cholerae PS-4.

We describe the genomic characteristics of Vibrio cholerae strain PS-4 that is unable to ferment sucrose on a thiosulfate citrate bile salt sucrose (TCBS) agar medium. This bacterium was isolated from the skin mucus of a freshwater pufferfish. The genome of strain PS-4 was sequenced to understand the sucrose nonfermenting phenotype. The gene encoding the sucrose-specific phosphotransferase system IIB (sucR) was absent, resulting in the defective sucrose fermenting phenotype. In contrast, genes encoding the glucose-specific transport system IIB (ptsG) and fructose-specific transport system IIB (fruA) showed acid production while growing with respective sugars. The overall genome relatedness indices (OGRI), such as in silico DNA-DNA hybridization (isDDH), average nucleotide identity (ANI), and average amino acid identity (AAI), were above the threshold value, that is, 70% and 95 to 96%, respectively. Phylogenomic analysis based on genome-wide core genes and the nonrecombinant core genes showed that strain PS-4 clustered with Vibrio cholerae ATCC 14035T. Further, genes encoding cholera toxin (ctx), zonula occludens toxin (zot), accessory cholera enterotoxin (ace), toxin-coregulated pilus (tcp), and lipopolysaccharide biosynthesis (rfb) were absent. PS-4 showed hemolytic activity and reacted strongly to the R antibody. Therefore, the Vibrio cholerae from the pufferfish adds a new ecological niche of this bacterium. IMPORTANCE Vibrio cholerae is native of aquatic environments. In general, V. cholerae ferments sucrose on thiosulfate citrate bile salt sucrose (TCBS) agar and produces yellow colonies. V. cholerae strain PS-4 described in this study is a sucrose nonfermenting variant associated with pufferfish skin and does not produce yellow colonies on TCBS agar. Genes encoding sucrose-specific phosphotransferase system IIB (sucR) were absent. The observed phenotype in the distinct metabolic pathway indicates niche-specific adaptive evolution for this bacterium. Our study suggests that the nonfermenting phenotype of V. cholerae strains on TCBS agar may not always be considered for species delineation.

Vibrio cholerae was found in cultured bullfrog.

Bullfrog is one of the most important economic aquatic animals in China that is widely cultured in southern China and is a key breed recommended as an industry of poverty alleviation in China. During recent years, a fatal bacterial disease has often been found in cultured bullfrogs. The clinical manifestations of the diseased bullfrogs were severe intestinal inflammation and an anal prolapse. A bacterial pathogen was isolated from the diseased bullfrog intestines. The bacterium was identified as Vibrio cholerae using morphological, biochemical and 16S rRNA phylogenetic analysis. In this study, V. cholerae was isolated and identified in diseased bullfrogs for the first time, providing a basis for the diagnosis and control of the disease. Therefore, attention should be paid to the modes of transmission of V. cholerae from bullfrog and formulate reasonable safety measures.

The enigma of Pacini's Vibrio cholerae discovery.

During the 1854 cholera outbreak in Florence, Italy, Filippo Pacini documented that the cause of the infection was a bacterium. This conclusion was also independently reached by John Snow during the 1854 cholera outbreak in London. By using an epidemiological method, Snow found that the infection spread through a polluted water network. Snow identified a water pump as the source of the disease. After removing the infected handle of this pump, the cases of cholera rapidly began to decrease. A microscopic examination of the water showed organic impurities but no bacteria. This discovery was ignored during Snow's lifetime. In contrast, through microscopy during the autopsies of cholera victims, Pacini observed that the disruption of their intestinal mucosa was closely associated with millions of the bacteria that he called Vibrio cholerae. Via histological techniques, Pacini detected that intestinal mucosa reabsorption dysfunction was the cause of debilitating diarrhoea, vomiting, severe dehydration and death. Nevertheless, his discovery of Vibrio cholerae was ignored during Pacini's lifetime. A survey of Pacini's autographic manuscripts suggests that Pacini and Snow may have shared mutual knowledge within their respective seminal papers. This survey also facilitates, for the first time, the creation of maps that illustrate the worldwide distribution of Pacini's cholera papers from 1854 to 1881. The consistent neglect of Pacini's discovery remains a true enigma.

Ultrasensitive pathogen detection with a rolling circle amplification-empowered multiplex electrochemical DNA sensor.

We report a highly sensitive and selective multiplex assay by empowering an electrochemical DNA sensor with isothermal rolling circle amplification. The assay could simultaneously detect and discriminate three common entero-pathogens in a single reaction, with femtomolar sensitivity. It is useful for field- or resource-limited settings.

High-throughput low-cost nl-qPCR for enteropathogen detection: A proof-of-concept among hospitalized patients in Bangladesh.

BACKGROUND: Diarrheal disease is a leading cause of morbidity and mortality globally, especially in low- and middle-income countries. High-throughput and low-cost approaches to identify etiologic agents are needed to guide public health mitigation. Nanoliter-qPCR (nl-qPCR) is an attractive alternative to more expensive methods yet is nascent in application and without a proof-of-concept among hospitalized patients. METHODS: A census-based study was conducted among diarrheal patients admitted at two government hospitals in rural Bangladesh during a diarrheal outbreak period. DNA was extracted from stool samples and assayed by nl-qPCR for common bacterial, protozoan, and helminth enteropathogens as the primary outcome. RESULTS: A total of 961 patients were enrolled; stool samples were collected from 827 patients. Enteropathogens were detected in 69% of patient samples; More than one enteropathogen was detected in 32%. Enteropathogens most commonly detected were enteroaggregative Escherichia coli (26.0%), Shiga toxin-producing E.coli (18.3%), enterotoxigenic E. coli (15.5% heat stable toxin positive, 2.2% heat labile toxin positive), Shigella spp. (14.8%), and Vibrio cholerae (9.0%). Geospatial analysis revealed that the median number of pathogens per patient and the proportion of cases presenting with severe dehydration were greatest amongst patients residing closest to the study hospitals." CONCLUSIONS: This study demonstrates a proof-of-concept for nl-qPCR as a high-throughput low-cost method for enteropathogen detection among hospitalized patients.

A method for correcting underestimation of enteric pathogen genome quantities in environmental samples.

Exposure to enteric pathogens in the environment poses a serious risk for infection and disease. The accurate detection and quantification of enteric pathogens in environmental samples is critical for understanding pathogen transport and fate and developing risk assessment models. In this study, we successfully applied TaqMan real-time PCR assays to quantitatively detect five human-specific pathogens (Shigella/EIEC, Salmonella Typhi, Vibrio cholera, Norovirus, and Giardia) in samples from open drains, canals, floodwater, septic tanks, and anaerobic baffled reactors (ABR) collected in Mirpur, Dhaka, Bangladesh from April to October 2019. Overall, the grab and sediment samples showed low inhibition but the ultrafiltration samples collected from open drain had significantly higher (P = 0.0049) degree of PCR inhibition (median Ct = 31.06) compared to the extraction controls (Ct = 28.54). We developed a two-step method to adjust underestimation of pathogen quantities due to PCR inhibition and non-optimum PCR efficiency. Compared to other sample types, ultrafiltration samples demonstrated a wide range of concentration increase (1.0%-182.5%) by pathogens after adjusting for PCR inhibition and non-optimum efficiencies. These quantitative qPCR assays are successful in quantifying multiple enteric pathogens in environmental samples, and the adjustment method would be useful for correcting underestimates of pathogen quantities due to partial PCR inhibition and non-optimum efficiency.

Sachet water consumption as a risk factor for cholera in urban settings: Findings from a case control study in Kinshasa, Democratic Republic of the Congo during the 2017-2018 outbreak.

BACKGROUND: Behavioural risk factors for cholera are well established in rural and semi-urban contexts, but not in densely populated mega-cities in Sub-Saharan Africa. In November 2017, a cholera epidemic occurred in Kinshasa, the Democratic Republic of the Congo, where no outbreak had been recorded for nearly a decade. During this outbreak, we investigated context-specific risk factors for cholera in an urban setting among a population that is not frequently exposed to cholera. METHODOLOGY/PRINCIPAL FINDINGS: We recruited 390 participants from three affected health zones of Kinshasa into a 1:1 matched case control study. Cases were identified from cholera treatment centre admission records, while controls were recruited from the vicinity of the cases' place of residence. We used standardized case report forms for the collection of socio-demographic and behavioural risk factors. We used augmented backward elimination in a conditional logistic regression model to identify risk factors. The consumption of sachet water was strongly associated with the risk of being a cholera case (p-value 0.019), which increased with increasing frequency of consumption from rarely (OR 2.2, 95% CI 0.9-5.2) to often (OR 4.0, 95% CI 1.6-9.9) to very often (OR 4.1, 95% CI 1.0-16.7). Overall, more than 80% of all participants reported consumption of this type of drinking water. The risk factors funeral attendance and contact with someone suffering from diarrhoea showed a p-value of 0.09 and 0.08, respectively. No socio-demographic characteristics were associated with the risk of cholera. CONCLUSIONS/SIGNIFICANCE: Drinking water consumption from sachets, which are sold informally on the streets in most Sub-Saharan African cities, are an overlooked route of infection in urban cholera outbreaks. Outbreak response measures need to acknowledge context-specific risk factors to remain a valuable tool in the efforts to achieve national and regional targets to reduce the burden of cholera in Sub-Saharan Africa.

Temporal shifts in antibiotic resistance elements govern phage-pathogen conflicts.

Bacteriophage predation selects for diverse antiphage systems that frequently cluster on mobilizable defense islands in bacterial genomes. However, molecular insight into the reciprocal dynamics of phage-bacterial adaptations in nature is lacking, particularly in clinical contexts where there is need to inform phage therapy efforts and to understand how phages drive pathogen evolution. Using time-shift experiments, we uncovered fluctuations in Vibrio cholerae's resistance to phages in clinical samples. We mapped phage resistance determinants to SXT integrative and conjugative elements (ICEs), which notoriously also confer antibiotic resistance. We found that SXT ICEs, which are widespread in γ-proteobacteria, invariably encode phage defense systems localized to a single hotspot of genetic exchange. We identified mechanisms that allow phage to counter SXT-mediated defense in clinical samples, and document the selection of a novel phage-encoded defense inhibitor. Phage infection stimulates high-frequency SXT ICE conjugation, leading to the concurrent dissemination of phage and antibiotic resistances.

CVD 103-HgR live, attenuated cholera vaccine strain viability in drinking waters from the US and Europe.

CVD 103-HgR live, attenuated oral cholera vaccine strain is indicated for single dose immunization against Vibrio cholerae, the causative agent for cholera. The vaccine packets containing buffer powder and lyophilized CVD 103-HgR are reconstituted in water and consumed. Studies were performed to explore the viability of CVD 103-HgR in drinking waters from common sources. CVD 103-HgR vaccine was reconstituted in bottled and tap waters from the United States and Europe, and viability was measured via colony forming units assay. Chemical analysis of select water samples was used to identify chemicals that have a negative effect on CVD 103-HgR viability. CVD 103-HgR titers were stable in all bottled waters tested, including purified bottled water, bottled spring water, and sparkling waters. However, tap water from certain cities in the US and Europe affected viability and are not compatible with vaccine. Water chemistry revealed that these tap waters contained copper, likely leached from copper plumbing. These studies give high confidence in the stability of CVD 103-HgR reconstituted in a variety of bottled waters. Waters containing copper, including tap water, should not be used to reconstitute CVD 103-HgR strain oral vaccine due to the common use of copper plumbing.

Duplex On-Site Detection of Vibrio cholerae and Vibrio vulnificus by Recombinase Polymerase Amplification and Three-Segment Lateral Flow Strips.

Vibrio cholerae and Vibrio vulnificus are two most reported foodborne Vibrio pathogens related to seafood. Due to global ocean warming and an increase in seafood consumption worldwide, foodborne illnesses related to infection of these two bacteria are growing, leading to food safety issues and economic consequences. Molecular detection methods targeting species-specific genes are effective tools in the fight against bacterial infections for food safety. In this study, a duplex detection biosensor based on isothermal recombinase polymerase amplification (RPA) and a three-segment lateral flow strip (LFS) has been established. The biosensor used lolB gene of Vibrio cholerae and empV gene of Vibrio vulnificus as the detection markers based on previous reports. A duplex RPA reaction for both targets were constructed, and two chemical labels, FITC and DIG, of the amplification products were carefully tested for effective and accurate visualization on the strip. The biosensor demonstrated good specificity and achieved a sensitivity of 101 copies per reaction or one colony forming unit (CFU)/10 g of spiked food for both bacteria. Validation with clinical samples showed results consistent with that of real-time polymerase chain reaction. The detection process was simple and fast with a 30-min reaction at 37 °C and visualization on the strip within 5 min. With little dependence on laboratory settings, this biosensor was suitable for on-site detection, and the duplex system enabled simultaneous detection of the two important foodborne bacteria. Moreover, the principle can be extended to healthcare and food safety applications for other pathogens.

Decades of cholera in Odisha, India (1993-2015): lessons learned and the ways forward.

Cholera is one of the major public health problems in the state of Odisha, India since centuries. The current paper is a comprehensive report on epidemiology of cholera in Odisha, which was documented from 1993. PubMed and Web of Knowledge were searched for publications reporting cholera in Odisha during the period 1993-2015. The search was performed using the keywords 'Odisha' and/or 'Orissa' and 'Cholera'. In addition, manual search was undertaken to find out relevant papers. During the study period, a total of 37 cholera outbreaks were reported with an average of >1.5 cholera outbreaks per year and case fatality ratio was 0.3%. Vibrio cholerae O1 Ogawa serotype was the major causative agent in most of the cholera cases. The recent studies demonstrated the prevalence of V. cholerae O1, El Tor variants carrying ctxB1, ctxB7 and Haitian variant tcpA allele associated with polymyxin B sensitivity and these variants are replacing the proto type El Tor. The first report of variant ctxB7 in Odisha during super-cyclone 1999 predicted its emergence and subsequent spread causing cholera outbreaks. The prevalence of multidrug-resistant V. cholerae at different time periods created alarming situation. The efficacy trial of oral cholera vaccine (OCV, Shanchol) in a public health set-up in Odisha has shown encouraging results which should be deployed for community level vaccination among the vulnerable population. This paper has taken an effort to disseminate the valuable information of epidemiology of cholera that will influence the policy-makers and epidemiologists for constant surveillance in other parts of Odisha, India and around the globe.

Resistencia antimicrobiana y factores de virulencia en aislados de Vibrio cholerae O1. Cuba, 2012-2015 / Antimicrobial resistance and virulence factors in Vibrio cholerae O1 isolates. Cuba, 2012-2015

Introducción: El cólera es una infección intestinal aguda causada por cepas toxigénicas de Vibrio choleare. La rápida diseminación y emergencia de la multirresistencia que caracteriza a este patógeno, podría interferir en el éxito de la terapia antimicrobiana, por lo que constituye una prioridad monitorear los cambios en los patrones de susceptibilidad, como parte trascendental de la política de control de la resistencia antimicrobiana. Objetivo: Determinar el comportamiento de la resistencia antimicrobiana frente a los antimicrobianos de interés empleados en el tratamiento, la presencia de factores de virulencia enzimáticos y si existe relación entre ambos. Métodos: Se realizó un estudio descriptivo de corte transversal durante julio de 2012 a diciembre de 2015. Se estudiaron 500 aislamientos pertenecientes al cepario del Laboratorio Nacional de Referencia de Enfermedades Diarreicas Agudas del Instituto de Medicina Tropical Pedro Kourí, procedentes de brotes de enfermedades diarreicas agudas de la red nacional de laboratorios de Microbiología de Cuba. Se aplicaron métodos convencionales fenotípicos para determinar el comportamiento de la resistencia antimicrobiana, la presencia de factores enzimáticos y la relación de estos con la resistencia antimicrobiana. Resultados: Los mayores porcentajes de sensibilidad se obtuvieron frente a azitromicina (98 por ciento), doxiciclina (96 por ciento) y ciprofloxacina (93 por ciento) y de resistencia frente a ampicilina (100 por ciento) y trimetoprim-sulfametoxazol (99,4 por ciento). Se encontraron 44 aislados (8,8 por ciento) multirresistente. Todos los aislamientos poseían al menos dos enzimas extracelulares como factores de virulencia, las más frecuentes: gelatinasa (96 por ciento) y lecitinasa (95 por ciento). Conclusiones: Se evidencia una relación directa y proporcional entre la presencia de los factores de virulencia y resistencia antimicrobiana, sinergismo que surgiere mayor patogenicidad de los aislados estudiados procedentes de brotes epidémicos(AU)

Introduction: Cholera is an acute intestinal infection caused by toxigenic strains of Vibrio choleare. The rapid dissemination and emergence of the multiresistance that characterizes this pathogen could interfere with the success of antimicrobial therapy, so it is a priority to monitor changes in susceptibility patterns, as a transcendental part of the resistance control policy antimicrobial. Objective: To determine the behavior of antimicrobial resistance against the antimicrobials of interest used in the treatment, the presence of enzymatic virulence factors and whether there is a relationship between them. Methods: A descriptive cross-sectional study was conducted during July 2012 to December 2015. Where 500 isolates belonging to the cepary of the National Reference Laboratory for Acute Diarrheal Diseases of the Institute of Tropical Medicine Pedro Kourí, from outbreaks of EDA of the national network of Microbiology laboratories in Cuba. Conventional phenotypic methods were applied to determine the behavior of antimicrobial resistance, the presence of enzymatic factors and their relationship with antimicrobial resistance. Results: The highest percentages of sensitivity were obtained against azithromycin (98 percent), doxycycline (96 percent) and ciprofloxacin (93 percent) and resistance to ampicillin (100 percent) and trimethoprim-sulfamethoxazole (99.4 percent). 44 isolated (8.8 percent) multi-resistant were found. All isolates had at least two extracellular enzymes as virulence factors, the most frequent: gelatinase (96 percent) and lecithinase (95 percent). Conclusions: There is a direct and proportional relationship between the presence of virulence factors and antimicrobial resistance, synergism that arises greater pathogenicity of the isolates studied from epidemic outbreaks(AU)

First report of Vibrio cholerae O9, novel st520, isolated from a child with bacteraemia-associated sepsis.

Vibrios have been identified to cause extra-intestinal complications apart from the occasional cholera-like diarrhoeal outbreaks. The non-O1/O139 Vibrio cholerae strains are ubiquitous in environmental water bodies and hence pose a threat to people even without obvious risk factors. We describe a case of sepsis in a child with spinal dysraphism caused by a V. cholerae O9 strain belonging to a novel sequence type (ST520). The present case highlights the need of considering V. cholerae non-O1/O139 as one of the pathogens while dealing with sepsis cases, and also, the study expounds the importance of proper characterisation of the pathogen for an effective treatment.

A prolonged cholera outbreak caused by drinking contaminated stream water, Kyangwali refugee settlement, Hoima District, Western Uganda: 2018.

BACKGROUND: On 23 February 2018, the Uganda Ministry of Health (MOH) declared a cholera outbreak affecting more than 60 persons in Kyangwali Refugee Settlement, Hoima District, bordering the Democratic Republic of Congo (DRC). We investigated to determine the outbreak scope and risk factors for transmission, and recommend evidence-based control measures. METHODS: We defined a suspected case as sudden onset of watery diarrhoea in any person aged ≥ 2 years in Hoima District, 1 February-9 May 2018. A confirmed case was a suspected case with Vibrio cholerae cultured from a stool sample. We found cases by active community search and record reviews at Cholera Treatment Centres. We calculated case-fatality rates (CFR) and attack rates (AR) by sub-county and nationality. In a case-control study, we compared exposure factors among case- and control-households. We estimated the association between the exposures and outcome using Mantel-Haenszel method. We conducted an environmental assessment in the refugee settlement, including testing samples of stream water, tank water, and spring water for presence of fecal coliforms. We tested suspected cholera cases using cholera rapid diagnostic test (RDT) kits followed by culture for confirmation. RESULTS: We identified 2122 case-patients and 44 deaths (CFR = 2.1%). Case-patients originating from Demographic Republic of Congo were the most affected (AR = 15/1000). The overall attack rate in Hoima District was 3.2/1000, with Kyangwali sub-county being the most affected (AR = 13/1000). The outbreak lasted 4 months, which was a multiple point-source. Environmental assessment showed that a stream separating two villages in Kyangwali Refugee Settlement was a site of open defecation for refugees. Among three water sources tested, only stream water was feacally-contaminated, yielding > 100 CFU/100 ml. Of 130 stool samples tested, 124 (95%) yielded V. cholerae by culture. Stream water was most strongly associated with illness (odds ratio [OR] = 14.2, 95% CI: 1.5-133), although tank water also appeared to be independently associated with illness (OR = 11.6, 95% CI: 1.4-94). Persons who drank tank and stream water had a 17-fold higher odds of illness compared with persons who drank from other sources (OR = 17.3, 95% CI: 2.2-137). CONCLUSIONS: Our investigation demonstrated that this was a prolonged cholera outbreak that affected four sub-counties and two divisions in Hoima District, and was associated with drinking of contaminated stream water. In addition, tank water also appears to be unsafe. We recommended boiling drinking water, increasing latrine coverage, and provision of safe water by the District and entire High Commission for refugees.

Genomics of the Argentinian cholera epidemic elucidate the contrasting dynamics of epidemic and endemic Vibrio cholerae.

In order to control and eradicate epidemic cholera, we need to understand how epidemics begin, how they spread, and how they decline and eventually end. This requires extensive sampling of epidemic disease over time, alongside the background of endemic disease that may exist concurrently with the epidemic. The unique circumstances surrounding the Argentinian cholera epidemic of 1992-1998 presented an opportunity to do this. Here, we use 490 Argentinian V. cholerae genome sequences to characterise the variation within, and between, epidemic and endemic V. cholerae. We show that, during the 1992-1998 cholera epidemic, the invariant epidemic clone co-existed alongside highly diverse members of the Vibrio cholerae species in Argentina, and we contrast the clonality of epidemic V. cholerae with the background diversity of local endemic bacteria. Our findings refine and add nuance to our genomic definitions of epidemic and endemic cholera, and are of direct relevance to controlling current and future cholera epidemics.

CO2-leakage-driven diffusiophoresis causes spontaneous accumulation of charged materials in channel flow.

We identify a phenomenon where the onset of channel flow creates an unexpected, charge-dependent accumulation of colloidal particles, which occurs in a common-flow configuration with gas-permeable walls, but in the absence of any installed source of gas. An aqueous suspension of either positively charged (amine-modified polystyrene; a-PS) or negatively charged (polystyrene; PS) particles that flowed into a polydimethylsiloxane (PDMS) channel created charge-dependent accumulation 2 to 4 min after the onset of flow. We unravel the phenomenon with systematic experiments under various conditions and model calculations considering permeability of the channel walls and [Formula: see text]-driven diffusiophoresis. We demonstrate that such spontaneous transport of particles is driven by the gas leakage through permeable walls, which is induced by the pressure difference between the channel and the ambient. Since the liquid pressure is higher, an outward flux of gas forms in the flow. We also observe the phenomenon in a bacterial suspension of Vibrio cholerae, where the fluorescent protein (mKO; monomeric Kusabira Orange) and bacterial cells show charge-dependent separation in a channel flow. Such experimental observations show that diffusiophoresis of charged particles in an aqueous suspension can be achieved by having gas leakage through permeable walls, without any preimposed ion-concentration gradient in the liquid phase. Our findings will help resolve unexpected challenges and biases in on-chip experiments involving particles and gas-permeable walls and help understand similar configurations that naturally exist in physiological systems, such as pulmonary capillaries. We also demonstrate potential applications, such as concentrating and collecting proteins below the isoelectric point.

The seventh pandemic of cholera in Europe revisited by microbial genomics.

In 1970, the seventh pandemic of cholera (7 P) reached both Africa and Europe. Between 1970 and 2011, several European countries reported cholera outbreaks of a few to more than 2,000 cases. We report here a whole-genome analysis of 1,324 7 P V. cholerae El Tor (7 PET) isolates, including 172 from autochthonous sporadic or outbreak cholera cases occurring between 1970 and 2011 in Europe, providing insight into the spatial and temporal spread of this pathogen across Europe. In this work, we show that the 7 PET lineage was introduced at least eight times into two main regions: Eastern and Southern Europe. Greater recurrence of the disease was observed in Eastern Europe, where it persisted until 2011. It was introduced into this region from Southern Asia, often circulating regionally in the countries bordering the Black Sea, and in the Middle East before reaching Eastern Africa on several occasions. In Southern Europe, the disease was mostly seen in individual countries during the 1970s and was imported from North and West Africa, except in 1994, when cholera was imported into Albania and Italy from the Black Sea region. These results shed light on the geographic course of cholera during the seventh pandemic and highlight the role of humans in its global dissemination.