Predicting quality and quantity of water used by urban households based on tap water service

AbstractDespite significant progress in improving access to safe water globally, inadequate access remains a major public health concern in low- and middle-income countries. We collected data on the bacterial quality of stored drinking water and the quantity of water used domestically from 416 households in Uvira, Democratic Republic of the Congo. An indicator of tap water availability was constructed using invoices from 3685 georeferenced piped water connections. We examined how well this indicator predicts the probability that a household’s stored drinking water is contaminated with Escherichia coli, and the total amount of water used at home daily, accounting for distance from alternative surface water sources. Probability of drinking water contamination is predicted with good discrimination overall, and very good discrimination for poorer households. More than 80% of the households are predicted to store contaminated drinking water in areas closest to the rivers and with the worst tap water service, where river water is also the most likely reported source of drinking water. A model including household composition predicts nearly two-thirds of the variability in the reported quantity of water used daily at home. Households located near surface water and with a poor tap water service indicator are more likely to use water directly at the source. Our results provide valuable information that supports an ongoing large-scale investment in water supply infrastructure in Uvira designed to reduce the high burden of cholera and other diarrhoeal diseases. This approach may be useful in other urban settings with limited water supply access.</jats:p

Confirmation of cholera by rapid diagnostic test amongst patients admitted to the cholera treatment centre in Uvira, Democratic Republic of the Congo.

INTRODUCTION: Cholera is endemic in the Eastern provinces of the Democratic Republic of the Congo since 1978, and Uvira in South-Kivu has been reporting suspected cholera cases nearly every week for over a decade. The clinical case definition for suspected cholera is relatively non-specific, and cases are rarely confirmed by laboratory methods, especially in endemic settings. This may lead to over-estimation of cholera cases and limit effective public health responses. METHODS AND RESULTS: Between April 2016 and November 2017, 69% of the 2,059 patients admitted to the Uvira Cholera Treatment Centre (CTC) were tested for cholera with rapid diagnostic tests (RDTs). Of those admitted as suspected cholera cases, only 40% tested positive for cholera, equivalent to an estimated annual incidence of suspected/confirmed cholera in Uvira of 43.8 and 16.3 cases per 10,000 inhabitants respectively. A multivariable logistic regression indicates that boys aged 2 to 4 years, girls aged 5 to 15 years and adult men are respectively 1.9, 2.1 and 1.8 times more likely to test positive than adult women. On the contrary, boys under 2 are 10 times less likely to test positive. The odds of testing positive also increase as weekly admissions to the CTC rise, with up to a 5-fold increase observed during the weeks with the highest numbers of admissions compared to the lowest ones. Other predictors of cholera confirmation include duration of stay at the CTC, clinical outcome of admission, lower weekly rainfall and area of residence in Uvira, with the northern part of town having the highest confirmation rate. CONCLUSION: Cholera is an on-going public health problem in Uvira but the majority of suspected cases admitted to the CTC were found to be negative for cholera after RDT testing. These findings may have important implications for cholera control strategies in favour of interventions that address cholera and other diarrhoeal diseases alike

A quantitative assessment method for Ascaris eggs on hands.

The importance of hands in the transmission of soil transmitted helminths, especially Ascaris and Trichuris infections, is under-researched. This is partly because of the absence of a reliable method to quantify the number of eggs on hands. Therefore, the aim of this study was to develop a method to assess the number of Ascaris eggs on hands and determine the egg recovery rate of the method. Under laboratory conditions, hands were seeded with a known number of Ascaris eggs, air dried and washed in a plastic bag retaining the washing water, in order to determine recovery rates of eggs for four different detergents (cationic [benzethonium chloride 0.1% and cetylpyridinium chloride CPC 0.1%], anionic [7X 1% - quadrafos, glycol ether, and dioctyl sulfoccinate sodium salt] and non-ionic [Tween80 0.1% -polyethylene glycol sorbitan monooleate]) and two egg detection methods (McMaster technique and FLOTAC). A modified concentration McMaster technique showed the highest egg recovery rate from bags. Two of the four diluted detergents (benzethonium chloride 0.1% and 7X 1%) also showed a higher egg recovery rate and were then compared with de-ionized water for recovery of helminth eggs from hands. The highest recovery rate (95.6%) was achieved with a hand rinse performed with 7X 1%. Washing hands with de-ionized water resulted in an egg recovery rate of 82.7%. This washing method performed with a low concentration of detergent offers potential for quantitative investigation of contamination of hands with Ascaris eggs and of their role in human infection. Follow-up studies are needed that validate the hand washing method under field conditions, e.g. including people of different age, lower levels of contamination and various levels of hand cleanliness

Prevalence and diversity of enteric pathogens among cholera treatment centre patients with acute diarrhea in Uvira, Democratic Republic of Congo.

BACKGROUND: Cholera remains a major global health challenge. Uvira, in the Democratic Republic of the Congo (DRC), has had endemic cholera since the 1970's and has been implicated as a possible point of origin for national outbreaks. A previous study among this population, reported a case confirmation rate of 40% by rapid diagnostic test (RDT) among patients at the Uvira Cholera Treatment Centre (CTC). This study considers the prevalence and diversity of 15 enteric pathogens in suspected cholera cases seeking treatment at the Uvira CTC. METHODS: We used the Luminex xTAG® multiplex PCR to test for 15 enteric pathogens, including toxigenic strains of V. cholerae in rectal swabs preserved on Whatman FTA Elute cards. Results were interpreted on MAGPIX® and analyzed on the xTAG® Data Analysis Software. Prevalence of enteric pathogens were calculated and pathogen diversity was modelled with a Poisson regression. RESULTS: Among 269 enrolled CTC patients, PCR detected the presence of toxigenic Vibrio cholerae in 38% (103/269) of the patients, which were considered to be cholera cases. These strains were detected as the sole pathogen in 36% (37/103) of these cases. Almost half (45%) of all study participants carried multiple enteric pathogens (two or more). Enterotoxigenic Escherichia coli (36%) and Cryptosporidium (28%) were the other most common pathogens identified amongst all participants. No pathogen was detected in 16.4% of study participants. Mean number of pathogens was highest amongst boys and girls aged 1-15 years and lowest in women aged 16-81 years. Ninety-three percent of toxigenic V. cholerae strains detected by PCR were found in patients having tested positive for V. cholerae O1 by RDT. CONCLUSIONS: Our study supports previous results from DRC and other cholera endemic areas in sub-Sahara Africa with less than half of CTC admissions positive for cholera by PCR. More research is required to determine the causes of severe acute diarrhea in these low-resource, endemic areas to optimize treatment measures. TRIAL REGISTRATION: This study is part of the impact evaluation study entitled: "Impact Evaluation of Urban Water Supply Improvements on Cholera and Other Diarrheal Diseases in Uvira, Democratic Republic of Congo" registered on 10 October 2016 at clinicaltrials.gov Identification number: NCT02928341

Assessing the impact of drinking water and sanitation on diarrhoeal disease in low- and middle-income settings: Systematic review and meta-regression

Objective: To assess the impact of inadequate water and sanitation on diarrhoeal disease in low- and middle-income settings. Methods: The search strategy used Cochrane Library, MEDLINE & PubMed, Global Health, Embase and BIOSIS supplemented by screening of reference lists from previously published systematic reviews, to identify studies reporting on interventions examining the effect of drinking water and sanitation improvements in low- and middle-income settings published between 1970 and May 2013. Studies including randomised controlled trials, quasi-randomised trials with control group, observational studies using matching techniques and observational studies with a control group where the intervention was well defined were eligible. Risk of bias was assessed using a modified Ottawa-Newcastle scale. Study results were combined using meta-analysis and meta-regression to derive overall and intervention-specific risk estimates. Results: Of 6819 records identified for drinking water, 61 studies met the inclusion criteria, and of 12 515 records identified for sanitation, 11 studies were included. Overall, improvements in drinking water and sanitation were associated with decreased risks of diarrhoea. Specific improvements, such as the use of water filters, provision of high-quality piped water and sewer connections, were associated with greater reductions in diarrhoea compared with other interventions. Conclusions: The results show that inadequate water and sanitation are associated with considerable risks of diarrhoeal disease and that there are notable differences in illness reduction according to the type of improved water and sanitation implemented

Transmission of helminth eggs through hands in a high-risk community.

BACKGROUND: The role that hands play in the transmission of Ascaris is not well understood. METHODS: A newly developed method to quantify the presence helminth eggs on hands was tested among a group of farmers in Vietnam. High turbidity in hand rinse samples meant that the adopted sugar solution had to be replaced by zinc sulphate as a flotation solution. RESULTS: The survey found 34% (31/90) of study participant hands' were positive for helminth eggs, though concentrations were low and ranged from 0-10 eggs/2 hands. The use of fresh excreta in agriculture was the only variable that showed an association with the concentrations of eggs found on hands. CONCLUSIONS: The results highlight the need to promote handwashing with soap to prevent the transmission of soil-transmitted helminth infections

Accuracy of the Kato-Katz, adhesive tape and FLOTAC techniques for helminth diagnosis among children in Kyrgyzstan.

The purpose of this study was to assess the accuracy of three copro-microscopic techniques for helminth diagnosis: Kato-Katz, adhesive tape and FLOTAC. A total of 163 children from a peri-urban municipality near Bishkek, Kyrgyzstan, participated and submitted multiple stool samples and adhesive tapes. Ninety children supplied at least two stool samples and two adhesive tapes. Three stool samples and three adhesive tapes were available from 71 and 64 children, respectively. From each stool sample, a single Kato-Katz thick smear was prepared and examined quantitatively. Additionally, the first stool sample was subjected to the FLOTAC technique and helminth eggs were counted. Adhesive tapes were checked for the presence of Enterobius vermicularis eggs. Using pooled results as a diagnostic 'gold' standard, the prevalence of Ascaris lumbricoides, E. vermicularis, Hymenolepis nana and Dicrocoelium dendriticum were 54.4%, 13.3%, 11.1% and 11.1%, respectively. Infection intensities were low. When compared to triplicate Kato-Katz, a single FLOTAC was more sensitive for the diagnosis of A. lumbricoides (89.5% versus 39.5%) and D. dendriticum (88.9% versus 33.3%), but less sensitive for H. nana (66.7% versus 88.9%). For E. vermicularis, three adhesive tapes showed much higher sensitivity than a single FLOTAC (92.9% versus 14.3%). FLOTAC yielded significantly higher faecal egg counts than Kato-Katz for A. lumbricoides and D. dendriticum. Overall results suggest that, although FLOTAC represents a promising technique for helminth diagnosis in Kyrgyzstan, the repeated adhesive tape test remains so far the method of choice for diagnosing E. vermicularis

Rapid appraisal of human intestinal helminth infections among schoolchildren in Osh oblast, Kyrgyzstan.

A population-representative lot quality assurance sampling (LQAS) survey was conducted in 2009 to determine the prevalence of intestinal helminth infections among schoolchildren across Osh oblast, Kyrgyzstan. The diagnostic approach consisted of duplicate Kato-Katz thick smears from a single stool sample and an adhesive tape test. A questionnaire was administered to identify risk factors for infections. A total of 1262 schoolchildren aged 6-15 years were recruited; 41% of them harboured at least one of the eight identified helminth species. The two most prevalent helminths were Ascaris lumbricoides (23.1%) and Enterobius vermicularis (19.3%). Lower prevalences were found for Hymenolepis nana (4.4%), Fasciola hepatica (1.9%) and Dicrocoelium dendriticum (1.8%). Washing raw vegetables was a protective factor with regard to A. lumbricoides infection (odds ratio (OR)=0.69, p=0.022); tap water was borderline protective (OR=0.56, p=0.057). Children of the richest families were at a lower risk of E. vermicularis infection than the poorest ones (OR=0.41, p=0.011). Sharing the bed with more than one person was a risk factor for E. vermicularis infection (OR=2.0, p=0.002). The results call for targeted interventions against intestinal helminths in Osh oblast. In a first stage, annual deworming of schoolchildren and other high-risk groups with albendazole or mebendazole should be implemented, and reliable diagnosis and additional anthelminthic drugs should be made available. Subsequently, transmission control including locally-adapted health education, improved water supply and adequate sanitation should become the central features

Dataset for "Confirmation of cholera by rapid diagnostic test amongst patients admitted to the cholera treatment centre in Uvira, Democratic Republic of the Congo"

Anonymised dataset containing details on patients admitted to the Uvira Cholera Treatment Centre (CTC) who were tested for cholera with rapid diagnostic tests (RDTs) between April 2016 and November 2017. Variables include: ID, Admission week, Weekly rain, Sex, Age group, Stay duration, Outcome, Residence area, ResidenceAS, and Confirmatio