Cholera outbreak caused by drinking unprotected well water contaminated with faeces from an open storm water drainage: Kampala City, Uganda, January 2019

Pathways of exposure to Vibrio Cholerae in an urban informal settlement in Nairobi, Kenya

Cholera is a diarrhoeal disease caused by Vibrio cholerae (V. cholerae) bacterium, with strains belonging to serogroups 01 and 0139 causing a huge proportion of the disease. V. cholerae can contaminate drinking water sources and food through poor sanitation and hygiene. This study aimed to identify environmental routes of exposure to V. cholerae within Mukuru informal settlement in Nairobi. We collected nine types of environmental samples (drinking water, flood water, open drains, surface water, shaved ice, raw produce, street food, soil, and public latrine swabs) over 12 months. All samples were analysed for V. cholerae by culture and qPCR, then qPCR-positive samples were quantified using a V. cholerae DNA standard. Data about the frequency of contact with the environment was collected using behavioural surveys. Of the 803 samples collected, 28.5% were positive for V. cholerae by qPCR. However, none were positive for V. cholerae by culture. V. cholerae genes were detected in majority of the environmental water samples (79.3%), including open drains, flood water, and surface water, but were only detected in small proportions of other sample types. Vibrio-positive environmental water samples had higher mean V. cholerae concentrations [2490-3469 genome copies (gc) per millilitre (mL)] compared to drinking water samples (25.6 gc/mL). Combined with the behavioural data, exposure assessment showed that contact with surface water had the highest contribution to the total V. cholerae exposure among children while ingestion of municipal drinking water and street food and contact with surface water made substantial contributions to the total V. cholerae exposure for adults. Detection of V. cholerae in street food and drinking water indicates possible risk of exposure to toxigenic V. cholerae in this community. Exposure to V. cholerae through multiple pathways highlights the need to improve water and sanitation infrastructure, strengthen food hygiene practices, and roll out cholera vaccination.

Modelling techniques in cholera epidemiology: A systematic and critical review

Diverse modelling techniques in cholera epidemiology have been developed and used to (1) study its transmission dynamics, (2) predict and manage cholera outbreaks, and (3) assess the impact of various control and mitigation measures. In this study, we carry out a critical and systematic review of various approaches used for modelling the dynamics of cholera. Also, we discuss the strengths and weaknesses of each modelling approach. A systematic search of articles was conducted in Google Scholar, PubMed, Science Direct, and Taylor & Francis. Eligible studies were those concerned with the dynamics of cholera excluding studies focused on models for cholera transmission in animals, socio-economic factors, and genetic & molecular related studies. A total of 476 peer-reviewed articles met the inclusion criteria, with about 40% (32%) of the studies carried out in Asia (Africa). About 52%, 21%, and 9%, of the studies, were based on compartmental (e.g., SIRB), statistical (time series and regression), and spatial (spatiotemporal clustering) models, respectively, while the rest of the analysed studies used other modelling approaches such as network, machine learning and artificial intelligence, Bayesian, and agent-based approaches. Cholera modelling studies that incorporate vector/housefly transmission of the pathogen are scarce and a small portion of researchers (3.99%) considers the estimation of key epidemiological parameters. Vaccination only platform was utilized as a control measure in more than half (58%) of the studies. Research productivity in cholera epidemiological modelling studies have increased in recent years, but authors used diverse range of models. Future models should consider incorporating vector/housefly transmission of the pathogen and on the estimation of key epidemiological parameters for the transmission of cholera dynamics.

Vibrio cholerae O1 and Escherichia coli O157:H7 from drinking water and wastewater in Addis Ababa, Ethiopia

BACKGROUND

In Addis Ababa, Ethiopia, open ditches along innner roads in residential areas serve to convey domestic wastewater and rainwater away from residences. Contamination of drinking water by wastewater through faulty distribution lines could expose households to waterborne illnesses. This prompted the study to assess the microbiological safety of wastewater and drinking water in Addis Ababa, identify the pathogens therein, and determine their antibiotic resistance patterns.

RESULTS VIBRIO CHOLERAE

O1, mainly Hikojima serotype, was isolated from 23 wastewater and 16 drinking water samples. Similarly, 19 wastewater and 10 drinking water samples yielded Escherichia coli O157:H7. V. cholerae O1 were 100% resistant to the penicillins (Amoxacillin and Ampicillin), and 51-82% were resistant to the cephalosporins. About 44% of the V. cholerae O1 isolates in this study were Extended Spectrum Beta-Lactamase (ESBL) producers. Moreover, 26% were resistant to Meropenem. Peperacillin/Tazobactam was the only effective β-lactam antibiotic against V. cholerae O1. V. cholerae O1 isolates showed 37 different patterns of multiple resistance ranging from a minimum of three to a maximum of ten antimicrobials. Of the E. coli O157:H7 isolates, 71% were ESBL producers. About 96% were resistant to Ampicillin. Amikacin and Gentamicin were very effective against E. coli O157:H7 isolates. The isolates from wastewater and drinking water showed multiple antibiotic resistance against three to eight antibiotic drugs.

CONCLUSIONS

Open ditches for wastewater conveyance along innner roads in residence areas and underground faulty municipal water distribution lines could be possible sources for V. cholerae O1 and E. coli O157:H7 infections to surrounding households and for dissemination of multiple drug resistance in humans and, potentially, the environment.

Modification of 3D-Printed PLA Structures Using Photo-Iniferter Polymerization: Toward On-Demand Antimicrobial Water Filters

Water filtration is an important application to ensure the accessibility of clean drinking water. As requirements and contaminants vary on a local level, adjustable filter devices and their evaluation with contaminants are required. Within this work, modular filter devices are designed featuring an adjustable surface functionalization. For this purpose, 3D-printed structures are created consisting of bio-based poly(lactic acid) (PLA) that are manufactured by extrusion printing. The surface of PLA is activated with amino groups that are used to install xanthates as chain transfer agents. Subsequently, photo-iniferter (PI) polymerization is used to create cationic polymer brushes on the surface of PLA substrates. Multiple surface characterization techniques are employed to prove successful growth of polymer brushes on PLA. After initial optimization studies on flat surfaces, filter devices are printed, functionalized, and used to remove bacteria from contaminated water. Significant reduction of the number of microorganisms is detected after filtration (single filtration or cycling) and contaminating organism can also be removed from freshwater samples by simple incubation with a 3D-printed filter. The herein developed setup for producing functional filter devices and probing their performance in affinity filtration is a useful platform technology, enabling the rapid testing of polymer brushes for such applications.

A multi-functional reagent suitable for 1-step rapid DNA intercalation fluorescence-based screening of total bacteria in drinking water

The prerequisites for rapid screening of total bacteria in drinking water are low detection limit and convenience. Inspired by commercial adenosine 5'-triphosphate (ATP) based total bacterial detection kits, we pursued likewise convenience but with much lower detection limit. Existing intercalation fluorescence-based techniques employ multiple reagents to permeate the cell membrane and intercalate dye into the DNA in discrete sequential steps. A simple multi-functional reagent is proposed to do the same within one step. Surfactants (TritonX and SDS), and intercalating dyes (SYBR green, SYBR gold) were examined for their mutual compatibility and augmented with EDTA. Evaluation was performed with Gram negative Escherichia coli K12 (E. coli K12) and Gram positive Bacillus subtilis (B. subtilis) at serial dilution ratios from 10^-6 to 10^-2. Comparison was made with absorbance (600 nm) measurements and a commercial ATP kit. Using charge integrated photodetection, the proposed 1-step reagent achieved an LOD (1.00 × 10^-6, B. subtilis) that is two orders of magnitude lower than that of ATP kit (LOD = 1.06× 10^-4). This means it could detect minute quantity of total bacteria that is otherwise undetected by the ATP kit.

The antimicrobial resistance profiles of Escherichia coli and Pseudomonas aeruginosa isolated from private groundwater wells in the Republic of Ireland

The role of the natural environment in the dissemination of antimicrobial resistant bacteria has been increasingly recognised in the literature. However, knowledge surrounding the critical factors and mechanisms mediating their occurrence is still limited, particularly in relatively 'pristine' groundwater environments. In the Republic of Ireland (RoI), a country characterised by high groundwater reliance, household-based (unregulated) wells provide drinking water to 11% of the population. These private wells are generally located in rural areas, where the risk of microbiological contamination is high due to intensive agricultural practices and high reliance on domestic wastewater treatment systems; both of which are also potential sources of antimicrobials and antimicrobial resistant bacteria. Accordingly, the current research sought to elucidate current rates of antimicrobial resistant bacteria and the principal factors associated with their presence in private wells in the RoI. A total of 250 samples (from 132 wells nationwide) were assessed for the presence of faecal (Escherichia coli) and environmental (Pseudomonas aeruginosa) bacteria, with single isolates from each contaminated sample tested phenotypically against 18 and 9 antimicrobials, respectively. Findings show that while 16.7% of E. coli (n = 8/48) were categorically resistant to ≥1 antimicrobial, with a further 79.2% classified as intermediately resistant, no categorical resistance was found among P. aeruginosa isolates (n = 0/6), with just one intermediately resistant isolate detected. Multivariate regression modelling indicates significantly higher odds of resistant E. coli detection in concurrence with elevated cattle density (OR = 1.028, p = 0.032), aligning with findings of highest resistance rates to veterinary antimicrobials (e.g., streptomycin = 14.6%, tetracycline = 12.5%, and ampicillin = 12.5%). Multivariate model results also suggest overland flow culminating in direct wellhead ingress as a primary ingress mechanism for resistant E. coli. Study findings may inform groundwater source protection initiatives and antimicrobial resistance surveillance moving forward.

Knowledge, Attitude, and Practice in a Sample of the Lebanese Population Regarding Cholera

The evaluation of knowledge, attitude, and practices towards an emerging disease is an essential component of public health preventive measures during an outbreak. In October 2022, an outbreak of cholera was reported in Lebanon, which is the first to be reported in the Middle Eastern country for 30 years. This study aimed to explore the level of knowledge as well as attitude and practice of the general public in Lebanon towards cholera. A self-administered structured questionnaire was distributed via an online link to individuals living in Lebanon during October-November 2022. The survey instrument comprised items to assess the sociodemographic data; questions on knowledge about cholera symptoms, transmission, and prevention; as well as attitude and practice questions. Our study involved 553 participants, with a median age of 24 years and a majority of females (72.5%). The results showed that the majority of respondents correctly identified diarrhea as a symptom of cholera and recognized the spread via contaminated water and food. Having a university level education compared with secondary school or less (adjusted odds ratio (aOR) = 2.09), being married compared with single (aOR = 1.67), and working in the medical field compared with unemployed (aOR = 4.19) were significantly associated with higher odds of having good cholera knowledge. Having good knowledge compared with having a poor level of cholera knowledge (aOR = 1.83) and older age (aOR = 1.03) were significantly associated with higher odds of having a good attitude towards cholera. The current study showed an overall high knowledge score on cholera among the Lebanese population. Nevertheless, gaps in cholera knowledge were identified and should be addressed, particularly among workers in the medical field. Thus, we recommend targeted health education to the general population that aims to strengthen the health resilience in the community.

Cholera Outbreaks in India, 2011–2020: A Systematic Review

Fecal contamination of water sources and open defecation have been linked to cholera outbreaks in India. However, a systematic review on the drivers responsible for these outbreaks has yet to be published. Here, we systematically review the published literature on cholera outbreaks in India between 2011 and 2020. We searched studies in English in three databases (MEDLINE, EMBASE, and Web of Science) and the Integrated Disease Surveillance Program that tracks cholera outbreaks throughout India. Two authors independently extracted data and assessed the quality of the included studies. Quantitative data on the modes of transmission reviewed in this study were assessed for any change over time between 2011–2015 and 2016–2020. Our search retrieved 10823 records initially, out of which 81 full-text studies were assessed for eligibility. Among these 81 studies, 20 were eligible for inclusion in this review. There were 565 reported outbreaks between 2011 and 2020 that led to 45,759 cases and 263 deaths. Outbreaks occurred throughout the year; however, they exploded with monsoons (June through September). In Tamil Nadu, a typical peak of cholera outbreaks was observed from December to January. Seventy-two percent (33,089/45,759) of outbreak-related cases were reported in five states, namely Maharashtra, West Bengal, Punjab, Karnataka, and Madhya Pradesh. Analysis of these outbreaks highlighted the main drivers of cholera including contaminated drinking water and food, inadequate sanitation and hygiene (including open defecation), and direct contact between households. The comparison between 2011–2015 and 2016–2020 showed a decreasing trend in the outbreaks that arose due to damaged water pipelines. Many Indians still struggle with open defecation, sanitation, and clean water access. These issues should be addressed critically. In addition, it is essential to interrupt cholera short-cycle transmission (mediated by households, stored drinking water and foodstuffs) during an outbreak. As cholera is associated with deprivation, socio-economic development is the only long-term solution.