Waterborne Infectious Diseases Research Articles

Stability Analysis of a Waterborne Infectious Disease Model with Infectious Saturation Effect on Bacterial Disease Transmission

Stability Analysis of a Waterborne Infectious Disease Model with Infectious Saturation Effect on Bacterial Disease Transmission

Access to drinking water and sewage treatment in Brazil: a challenge for the control of waterborne infectious diseases

Access to drinking water and sewage treatment in Brazil: a challenge for the control of waterborne infectious diseases

Exploring private water wells for fecal sources and evidence of pathogen presence in the context of current testing practices for potability in Ontario

Abstract Private water wells provide drinking water for an estimated 4.1 million households in Canada yet remain understudied in the context of microbial water quality or human health impacts. As there exists little systematic surveillance for enteric infections or outbreaks related to well water sources, consumers may be at risk of waterborne infectious diseases. A standard protocol in Ontario requires 200 mL of water, collected, and submitted by well owners, half of which is used to analyze for Escherichia coli and total coliforms (TCs). The aim of this study was to determine the efficacy of testing small water volumes and to survey for other contaminants in addition to bacterial indicators to inform pathogen prevalence and fecal source in drinking water wells. Samples were assessed for E. coli and TCs, by culture, and genetic markers of Bacteroides spp., Campylobacter spp., Salmonella spp., and Shiga toxin-producing E. coli, using qPCR. The source of fecal contamination varied by the geographic region and may be explained by septic tank density and underlying geology, among other factors. A small number of samples (1.9%) showed the evidence of contamination with enteric pathogens. Lastly, E. coli measured by qPCR, as opposed to culture, correlated more strongly to Bacteroides markers.

Sero-prevalence of viral hepatitis A in a district of Sri Lanka: a community based cross-sectional study

BackgroundHepatitis A Virus (HAV) is one of the most common food and water borne infectious disease prevailing globally. The objective of the study was to determine sero-prevalence of HAV infection in a district of Sri Lanka.MethodsThis was a descriptive cross sectional study conducted on 1403 participants aged 1 year and above selected by multistage stratified (for age group and area of residence) cluster sampling from September 2015 to December, 2016. An interviewer-administered questionnaire was used to collect data and Anti-IgG testing was done to determine sero-positivity. The overall, the age and sex specific sero-prevalence of HAV were calculated with 95% confidence intervals (CI).ResultsOf the 1403 participants 1132 were anti HAV IgG positive. Therefore the overall sero-prevalence of HAV infection was 80.7% (95%CI: 78.64–82.76). There were 283 (20.2%) individuals below the age group of 14 years and below and out of them, 204 had anti HAV IgG, therefore sero-prevalence was 72.1% for that age group. The age group 15 years and aboe comprised of 1120 (79.8%) participants and of them 928 had anti HAV IgG, making sero-prevalence 82.9%. The lowest sero-prevalence (66.9%, n = 232) was observed in the age group of 11–20 years followed by 21–30 age group. From age 31 years onwards, the sero-prevalence exceeded 90%, reaching 100% after 71 years. The urban population showed a sero-prevalence of 83% (n = 195) and 80.2% (n = 937) for the rural sector while females had a sero-prevalence of 82.2% (n = 766) and it was 77.7% (n = 366) for males. Thirty-four (3.0%) participants who had sero-positive results (n = 1132) claimed that they have had HAV in the past.ConclusionsOverall, four fifth of the population was immune to HAV infection in the district of Gampaha.

Bitlis State Hospital 2016 assessment of food and water-borne infectious disease applications

Su ve besin kaynaklı bulaşıcı hastalıklar, gelişmiş ve gelişmekte olan ülkelerde morbidite ve mortaliteye artıran önemli bir halk sağlığı sorunudur. Bu yazıda Bitlis Devlet Hastanesine 2016 yılında başvuran, su ve besin kaynaklı bulaşıcı hastalık tanısı almış olgular değerlendirilmiştir.

Water, sanitation and mortality in Swiss towns in the context of urban renewal in the late nineteenth century

ABSTRACTThe modernisation of water supply and sanitation in Swiss towns at the end of the nineteenth century contributed to a reduction in waterborne infectious diseases such as typhoid fever. We analyse the association between mortality rates and these large-scale urban infrastructure projects in 15 major Swiss towns between 1876 and 1901. During this period, Switzerland experienced a rapid economic development and modernisation as well as rising living standards. We used panel data regression models with fixed effects to estimate the effects of the sanitary reforms. In 1876, the average typhoid fever mortality rate was 87 deaths per 100,000 people. In 1901 it had decreased to 10 deaths. We find that the introduction of modern water supply reduced typhoid fever mortality rates by 22 percent. Finally, we show that the modernisation of this central urban infrastructure was a complex, step-by-step process.

Spatial and temporal analysis of Hepatitis A cases in fier district, Albania, 1986–2016

Purpose: To document long term changes in the prevalence of Hepatitis A and its use as an indicator of sanitary standards and public health capacity. Methods & Materials: Registers of infectious disease cases maintained by Public Health authorities in Fier District, Albania for the years 1986 – 2016 inclusive were scanned and digitised as part of national project to quantify the burden of such diseases in the population. In total over 21,000 individual records covering 29 separate diseases were computerized of which Hepatitis A was the most common diagnosis with nearly 9,000 recorded cases over the 31-year period. For each case, demographic and biographic details of the patient, as well as key dates such as onset of symptoms, first visit to doctor or clinic, diagnosis, recovery and reporting to PH authorities were recorded. Spatial and temporal analysis of the data were carried out to identify long term trends and geographical distribution of cases. Results: Overall, there was a significant decrease in the number of cases of Hepatitis A from nearly 1300 per year 1986 to less than 100 cases annually from 2003 onwards. In the 4 years 2010 to 2014, a total of 18 cases were recorded. The following year, however, the number of reported cases rose to 92, of which 50 were recorded in a single commune. This outbreak was the subject of substantial media coverage and a detailed investigation by public health authorities which identified a number of contributing factors. Throughout the time series, outbreaks of Hepatitis A occurred at intervals of roughly 4-6 years, the periodicity possibly reflecting waning levels of immunity in the paediatric population. There was also a progressive reduction in the duration of clinical cases (date of first symptoms to date of recovery) attributed to more effective therapeutic options and better overall standards of health care. Conclusion: Using Hepatitis A as a proxy for water borne infectious diseases, the study demonstrated the effects of improvements in water and sewage infrastructure over three decades on the health of the population of Fier District. Continued sporadic cases and localised outbreaks could be used to identify communities where further investment was needed.

Spatiotemporal Error in Rainfall Data: Consequences for Epidemiologic Analysis of Waterborne Diseases.

The relationship between rainfall, especially extreme rainfall, and increases in waterborne infectious diseases is widely reported in the literature. Most of this research, however, has not formally considered the impact of exposure measurement error contributed by the limited spatiotemporal fidelity of precipitation data. Here, we evaluate bias in effect estimates associated with exposure misclassification due to precipitation data fidelity, using extreme rainfall as an example. We accomplished this via a simulation study, followed by analysis of extreme rainfall and incident diarrheal disease in an epidemiologic study in Ecuador. We found that the limited fidelity typical of spatiotemporal rainfall data sets biases effect estimates towards the null. Use of spatial interpolations of rain-gauge data or satellite data biased estimated health effects due to extreme rainfall (occurrence) and wet conditions (accumulated totals) downwards by 35%-45%. Similar biases were evident in the Ecuadorian case study analysis, where spatial incompatibility between exposed populations and rain gauges resulted in the association between extreme rainfall and diarrheal disease incidence being approximately halved. These findings suggest that investigators should pay greater attention to limitations in using spatially heterogeneous environmental data sets to assign exposures in epidemiologic research.

Molecular detection of Escherichia coli in Wadi Hanifa, Saudi Arabia

Background: The threat of controlling water borne infectious diseases was always a challenge for health authorities because water related diseases are a major cause of morbidity and mortality worldwide. Faecal coliforms such as Esherichia coli (E. coli) are the indicators most commonly analysed to evaluate the level of faecal contamination in water. Objectives: The study aimed in the first part to compare different techniques for the best detection of E. coli from water. The chosen method was applied in the second part on samples from Wadi Hanifa and neighboring wells. Colonies considered as E. coli were subjected to single colony PCR targeting the genes hha (indicator of enteric bacteria) and tuf (indicator of E. coli), in order to determine if there is a correlation between positive results given with both genes, thus the gene hha could be used as an indicator of fecal contamination in water. Material and methods: 3 techniques of water concentration for the detection of E. coli in artificially contaminated tap water with K12 (E. coli) were compared: (i) The European directive ISO 9308-1 (ii) Ultrafiltration method (UF) and (iii) Membrane filtration followed by direct isolation of genomic DNA. The best technique was applied for E. coli detection in 156 samples collected monthly and during one year from Wadi Hanifa and neighboring wells in Riyadh. Presumptive E. coli strains were subjected to single colony PCR targeting the genes hha and tuf. Results: The comparison of the three techniques has shown that the ISO 9308-1 was more reliable, accurate and economic than the other two tested techniques. Ten (10) E. coli strains (6.41%) were found exclusively in the surface water of Wadi Hanifa whereas; no E. coli strain was detected in wells, fortunately. All E. coli strains tested positive for the gene tuf, were found also positive for the gene hha. Conclusion: The ISO 9308-1 was the technique of choice for the detection and enumeration of coliforms and E. coli in water samples. A good correlation was found between the two genes suggesting that the gene hha could be used as indicator of fecal contamination in water samples.

How Did Data Visualization Identify and Improve Response to an Enteric Fever Outbreak in Syria?

Background: Population displacement and damage to infrastructure in Syria has contributed to an increase in water borne infectious diseases including enteric fever. The collection, presentation and analysis of data collected in real time is therefore vital for early identification of outbreaks. EWARN and EWARS are used in Syria for the reporting of communicable diseases however this is not always available to facilities in real time. As such, the prompt availability of diagnostics and treatment may be lacking. This is vital for enteric fever where morbidity and mortality without appropriate treatment is high. Objective: In this study, we examine the utility of a data visualization tool to track cases of enteric fever in three facilities supported by the Syrian American Medical Society (SAMS). Methods: All cases of enteric fever between March 2017 and July 2017 were tracked in near real time and presented using data visualization software, namely Tableau. Tableau is a visualization software generally used within the business sector, but its ability to visually express data has far reaching potential in the realm of public health. Sites in Daraa, Quneitra and Rural Damascus were included. Close communication with data personnel in SAMS country offices and health workers working in the facilities was maintained. Results: In March 2017, there were 21 cases of enteric fever across the three governorates and in July 2017, this had increased to 784 cases. Close liaison with the teams on the ground identified that facilities were seeing a significant increase in cases and that there was a shortage of appropriate antibiotics to treat patients. It was also apparent that there was a shortage of microbiology facilities which could isolate the causative organisms (Salmonella typhi or paratyphi) and therefore limited ability to identify the susceptibility of the organisms resulting in empiric therapy where available. Using data visualization in real time can allow for preparedness and responsiveness to outbreaks of communicable diseases during the conflict. Conclusions: Visualization should be integrated into online and offline data collection tools in order to create an early warning system on each device used in the field.

On the intrinsic dynamics of bacteria in waterborne infections

The intrinsic dynamics of bacteria often play an important role in the transmission and spread of waterborne infectious diseases. In this paper, we construct mathematical models for waterborne infections and analyze two types of nontrivial bacterial dynamics: logistic growth, and growth with Allee effects. For the model with logistic growth, we find that regular threshold dynamics take place, and the basic reproduction number can be used to characterize disease extinction and persistence. In contrast, the model with Allee effects exhibits much more complex dynamics, including the existence of multiple endemic equilibria and the presence of backward bifurcation and forward hysteresis.

Heterogeneous treatment effects of safe water on infectious disease: Do meteorological factors matter?

Mortality from waterborne infectious diseases remains a serious issue globally. Investigating the efficient laying plan of waterworks to mitigate the risk factors for such diseases has been an important research avenue for industrializing countries. While a growing body of the literature has revealed the mitigating effects of water-purification facilities on diseases, the heterogeneous treatment effects of clean water have been understudied. The present study thus focuses on the treatment effect heterogeneity of piped water with respect to the external meteorological environment of cities in industrializing Japan. To estimate the varying effects, we implement fixed-effects semivarying coefficient models to deal with the unobservable confounding factors, using a nationwide city-level panel dataset between 1922 and 1940. We find evidence that the magnitude of safe water on the reduction in the typhoid death rate is larger in cities with a higher temperature, which is consistent with recent epidemiological evidence. These findings underscore the importance of the variations in the external meteorological conditions of the municipalities that install water-purification facilities in developing countries.

Exploring links between water quality and E. coli O157:H7 survival potential in well waters from a rural area of southern Changchun City, China.

Waterborne infectious disease outbreak associated with well water contamination is a worldwide public health issue, especially for rural areas in developing countries. In the current study, we characterized 20 well water samples collected from a rural area of southern Changchun city, China, and investigated the survival potential of Escherichia coli O157:H7 in those water samples. The results showed that nitrate and ammonia concentrations in some well water samples exceed the corresponding China drinking water standards, indicating potential contamination by local agricultural farms. Our results also revealed that the average survival time (ttd) of E. coli O157:H7 in all well water samples was 30.09 days, with shortest and longest ttd being 17.95 and 58.10 days, respectively. The ttds were significantly correlated with pH and the ratio of total nitrogen to total phosphorus. In addition, it was found that the shape parameter (p) and first decimal reduction parameter (δ) were negatively (P < 0.05) and positively (P < 0.05) correlated to ttd, respectively. Our study showed that E. coli O157:H7 could survive up to two months in well water, suggesting that this pathogen could constitute a great public health risk.

Use of surrogate indicators for the evaluation of potential health risks due to poor urban water quality: A Bayesian Network approach.

Urban water pollution poses risks of waterborne infectious diseases. Therefore, in order to improve urban liveability, effective pollution mitigation strategies are required underpinned by predictions generated using water quality models. However, the lack of reliability in current modelling practices detrimentally impacts planning and management decision making. This research study adopted a novel approach in the form of Bayesian Networks to model urban water quality to better investigate the factors that influence risks to human health. The application of Bayesian Networks was found to enhance the integration of quantitative and qualitative spatially distributed data for analysing the influence of environmental and anthropogenic factors using three surrogate indicators of human health risk, namely, turbidity, total nitrogen and fats/oils. Expert knowledge was found to be of critical importance in assessing the interdependent relationships between health risk indicators and influential factors. The spatial variability maps of health risk indicators developed enabled the initial identification of high risk areas in which flooding was found to be the most significant influential factor in relation to human health risk. Surprisingly, population density was found to be less significant in influencing health risk indicators. These high risk areas in turn can be subjected to more in-depth investigations instead of the entire region, saving time and resources. It was evident that decision making in relation to the design of pollution mitigation strategies needs to account for the impact of landscape characteristics on water quality, which can be related to risk to human health.

Immunoprevalence to Six Waterborne Pathogens in Beachgoers at Boquerón Beach, Puerto Rico: Application of a Microsphere-Based Salivary Antibody Multiplex Immunoassay

Waterborne infectious diseases are a major public health concern worldwide. Few methods have been established that are capable of measuring human exposure to multiple waterborne pathogens simultaneously using non-invasive samples such as saliva. Most current methods measure exposure to only one pathogen at a time, require large volumes of individual samples collected using invasive procedures, and are very labor intensive. In this article, we applied a multiplex bead-based immunoassay capable of measuring IgG antibody responses to six waterborne pathogens simultaneously in human saliva to estimate immunoprevalence in beachgoers at Boquerón Beach, Puerto Rico. Further, we present approaches for determining cutoff points to assess immunoprevalence to the pathogens in the assay. For the six pathogens studied, our results show that IgG antibodies against antigens from noroviruses GI.I and GII.4 were more prevalent (60 and 51.6%, respectively) than Helicobacter pylori (21.4%), hepatitis A virus (20.2%), Campylobacter jejuni (8.7%), and Toxoplasma gondii (8%) in the saliva of the study participants. The salivary antibody multiplex immunoassay can be used to examine immunoprevalence of specific pathogens in human populations.

Small-unit water purifiers for remote military outposts: A new application of multicriteria decision analysis

During the U.S. military's first 145 years, waterborne and other infectious diseases caused more casualties than battlefield injuries, underscoring the importance of clean drinking water to military success. Ensuring drinking water safety poses special challenges to the U.S. Army Special Operations Forces, because treatment equipment used in the conventional Army is too heavy and operationally complex to deploy to remote outposts. Due to the lack of purpose-built water purifiers, Special Forces often rely on commercial-off-the-shelf systems, but guidelines on selecting optimal systems for specific deployment contexts are lacking. To fill this gap, this research examines whether multicriteria decision analysis (MCDA) can provide an operational framework for selecting water purifiers for Special Forces. Our objectives are to apply MCDA to help an officer preparing for village stability operations in Afghanistan select a water purifier and to assess whether other Army stakeholders agree with the officer's choice. In addition, because previous research has suggested that alternative MCDA methods can yield different rankings of decision alternatives, we test whether the MCDA method used is as important as who conducts the ranking. Toward these objectives, we use 4 MCDA approaches for eliciting preferences among 4 water purifiers from the deploying officer and 6 other Army stakeholders. The results show that regardless of method, the officer and 5 of the 6 stakeholders identified the same preferred alternative, although rankings for the less preferred water purifiers varied by method (intermethod rank-order correlation = .57). In responses to survey questions, stakeholders indicated that they would support using the results to support decisions about water purifier acquisition (average support = 5.3 on a 0–6 Likert scale with 6 indicating strongest support).

Disparities in death: Inequality in cause-specific infant and child mortality in Stockholm, 1878‒1926

Background: The decline of child mortality during the late 19th century is one of the most significant demographic changes in human history. However, there is evidence suggesting that the substantial reductions in mortality during the era did little to reduce mortality inequality between socioeconomic groups.Objective: The aim of this study is to examine the development of socioeconomic inequalities in cause-specific infant and child mortality during Stockholm’s demographic transition.Methods: Using an individual-level longitudinal population register for Stockholm, Sweden, between 1878 and 1926, I estimate Cox proportional hazards models to study how inequality in cause-specific hazards of dying from six categories of causes varied over time. The categories included are 1) airborne and 2) food and waterborne infectious diseases, 3) other infectious diseases, 4) noninfectious diseases and accidents, 5) perinatal causes, and 6) unspecified causes.Results: The results show that class differentials in nearly all causes of death converged during the demographic transition. The only exception was the airborne infectious disease category, for which the gap between white-collar and unskilled blue-collar workers widened over time.Conclusions: The results demonstrate that, even in a context of falling mortality and a changing epidemiological environment, higher socioeconomic groups were able to maintain a health advantage for their children by reducing their risks of dying from airborne disease to a greater extent than other groups. Potential explanations for these patterns are suggested, as well as suggestions for future research.Contribution: This is the first paper to use individual-level cause-of-death data to study the long-term trends in inequality of cause-specific child mortality during the demographic transition.

Doenças infecciosas e parasitárias por veiculação hídrica e doenças respiratórias em área industrial, Norte do Brasil

Resumo A cidade de Barcarena, no Estado do Pará, é um importante polo industrial que, nos últimos anos, esteve sujeita a registros de incidentes ambientais. Neste estudo, foi apresentado o perfil de morbidade por doenças infecciosas e parasitárias (DIP) de veiculação hídrica e por doenças respiratórias (DR) em indivíduos residentes do município de Barcarena, no período de 2008 a 2012. A pesquisa foi realizada com dados secundários sobre mortalidade e internações, obtidos a partir do Departamento de Informática do Sistema Único de Saúde (DATASUS). O coeficiente médio de mortalidade para as DIP apresentou 0,37 óbito por 1.000 habitantes. A faixa etária mais afetada pelos casos de internações por DIP foi a de 0 a 5 anos, com coeficiente médio de incidência na ordem de 31,8 por 100 mil habitantes. Para as DR, as crianças com faixa etária de 0 a 14 anos foram, aparentemente, as mais expostas, com 62,85%, e os idosos acima de 60 anos, com 15,16% dos casos. As taxas de incidência e de mortalidade por DR ficaram na ordem de 39 por 100 mil habitantes. Os indicadores de saúde estudados nos alertam um risco para à saúde de populações em Barcarena e sugerem estudos quantitativos e qualitativos mais específicos de possíveis contaminações ambientais na região.

DOES WATER DISINFECTANT PLAY A SUPPORTIVE ROLE IN THE SPREAD OF INFECTIOUS DISEASE? A MATHEMATICAL STUDY

The waterborne diseases cause millions of deaths across the globe. It was a preconceived notion since years that ingestion of contaminated water is the only possible way for the spread of waterborne infectious diseases. But some recent studies have shown that waterborne disease can also spread as a result of human to human transmission. The use of disinfectants is a common practice to prevent a waterborne disease. We assume that the inclusion of the disinfectant, although helpful in prevention of disease, caused negative effect on individuals. In this paper, a nonlinear mathematical model has been proposed to analyze the negative effects caused by disinfectant of water on individuals. Our study shows that if the mixing of disinfectant has not been performed in a controlled manner, then it results in an increase in human to human transmission of disease. The equilibrium and stability analysis have been performed to study the nature of the model system. An extensive numerical experiment has been performed to support the analytical findings.

Postdisaster epidemiological assessment of Koshi flood 2008, in Nepal

Introduction: Nepal is vulnerable to geological and hydrological natural disasters with vast epidemiological consequences. Objective: This research is focused on the epidemiology of the aftermath of a major flood in Koshi in the eastern part of Nepal in August 2008. Although, direct flood induced mortality was only two, 39 more mortalities were reported within the four months of the disaster event, mostly amongst those living in the rehabilitation camps. Methods and Materials: Data were collected through questionnaire survey and the secondary data from District Public Health Office (DPHO), Sunsari and well as local health centers. Results: The waterborne infectious diseases and mental disorders were found as the major prominent diseases during the post flood period. The infectious diseases increased by 30% in the first year after the disaster whereas the number of mental disorder patients increased immediately and also within one to three years of period from 29.2% to 62.5% during the post disaster phase. Conclusion: The study has found that the effectiveness of epidemiological interventions would be efficient if it continues up to two years after the flood.