Infectious Diseases in a Changing Climate

This JAMA Insights in the Climate Change and Health series discusses the importance of clinicians having awareness of changes in the geographic range, seasonality, and intensity of transmission of infectious diseases to help them diagnose, treat, and prevent these diseases.

Climate change and its impact on infectious diseases in Asia

ABSTRACT

Climate change, particularly increasing temperature, changes in rainfall, extreme weather events and changes in vector ecology, impacts the transmission of many climate-sensitive infectious diseases. Asia is the world's most populous, rapidly evolving and diverse continent, and it is already experiencing the effects of climate change. Climate change intersects with population, sociodemographic and geographical factors, amplifying the public health impact of infectious diseases and potentially widening existing disparities. In this narrative review, we outline the evidence of the impact of climate change on infectious diseases of importance in Asia, including vector-borne diseases, food- and water-borne diseases, antimicrobial resistance and other infectious diseases. We also highlight the imperative need for strategic intersectoral collaboration at the national and global levels and for the health sector to implement adaptation and mitigation measures, including responsibility for its own greenhouse gas emissions.

Microbial Waterborne Diseases in India: Status, Interventions, and Future Perspectives

Water plays a vital role as a natural resource since life is unsustainable without it. If water is polluted or contaminated, it results in several health issues among people. Millions of people are infected with waterborne diseases globally, and India is no exception. In the present review, we have analyzed the outbreaks of waterborne diseases that occurred in several Indian states between 2014 and 2020, identified the key infections, and provided insights into the performance of sanitation improvement programs. We noted that acute diarrheal disease (ADD), typhoid, cholera, hepatitis, and shigellosis are common waterborne diseases in India. These diseases have caused about 11,728 deaths between 2014 and 2018 out of which 10,738 deaths occurred only after 2017. The outbreaks of these diseases have been rising because of a lack of adequate sanitation, poor hygiene, and the absence of proper disposal systems. Despite various efforts by the government such as awareness campaigns, guidance on diet for infected individuals, and sanitation improvement programs, the situation is still grim. Disease hotspots and risk factors must be identified, water, sanitation, and hygiene (WASH) services must be improved, and ongoing policies must be effectively implemented to improve the situation. The efforts must be customized to the local environment. In addition, the possible effects of climate change must be projected, and strategies must be accordingly optimized.

Estimating Waterborne Infectious Disease Burden by Exposure Route, United States, 2014

More than 7.15 million cases of domestically acquired infectious waterborne illnesses occurred in the United States in 2014, causing 120,000 hospitalizations and 6,600 deaths. We estimated disease incidence for 17 pathogens according to recreational, drinking, and nonrecreational nondrinking (NRND) water exposure routes by using previously published estimates. In 2014, a total of 5.61 million (95% credible interval [CrI] 2.97-9.00 million) illnesses were linked to recreational water, 1.13 million (95% CrI 255,000-3.54 million) to drinking water, and 407,000 (95% CrI 72,800-1.29 million) to NRND water. Recreational water exposure was responsible for 36%, drinking water for 40%, and NRND water for 24% of hospitalizations from waterborne illnesses. Most direct costs were associated with pathogens found in biofilms. Estimating disease burden by water exposure route helps direct prevention activities. For each exposure route, water management programs are needed to control biofilm-associated pathogen growth; public health programs are needed to prevent biofilm-associated diseases.

Waterborne diseases and ethnic-related disparities: A 10 years nationwide mortality and burden of disease analysis from Ecuador

Background

Despite worldwide progress in terms of clean water supply, sanitation, and hygiene knowledge, some middle and most of low-income countries are still experiencing many diseases transmitted using unsafe water and the lack of sanitation.

Methods

To understand the impact of all waterborne diseases (WBD) registered in Ecuador. We performed a population-based analysis of all cases and deaths due to WBD in Ecuador based on the national public databases of hospital discharges as a proxy of incidence, in-hospital mortality, and countrywide general mortality rates from 2011 to 2020.

Results

In Ecuador, mestizos (mixed European and Indigenous American ancestry) had the greatest morbidity rate (141/100,000), followed by indigenous (63/100,000) and self-determined white patients (21/100,000). However, in terms of mortality, indigenous population have the greatest risk and rates, having a 790% additional mortality rate (2.6/100,000) than the reference group (self-determined white populations) at 0.29/100,000. The burden of disease analysis demonstrated that indigenous had the highest burden of disease caused by WBD with 964 YLL per every 100,000 people while mestizos have 360 YYL per 100,000 and self-determined white Ecuadorians have 109 YYL per 100,000.

Conclusions

In Ecuador, waterborne diseases (WBD) are still a major public health problem. We found that indigenous population had higher probability of getting sick and die due to WBD than the rest of the ethnic groups in Ecuador. We also found that younger children and the elderly are more likely to be admitted to the hospital due to a WBD. These epidemiological trends are probably associated with the lower life expectancy found among Indigenous than among the rest of the ethnic groups, who die at least, 39 years earlier than the self-determined white populations, 28 years earlier than Afro-Ecuadorians and 12 years earlier than the mestizos.

Expected annual probability of infection: A flood-risk approach to waterborne infectious diseases

This study introduces a new approach for the investigation of infections after an accidental ingestion of contaminated floodwater. The concept of Expected Annual Probability of Infection (EAPI) is introduced and implemented in an infection risk-model approach, by combining a Quantitative Microbial Risk Assessment (QMRA) with the four steps in flood risk assessment. Two groups and exposure paths are considered: adults wading in floodwater and small children swimming/playing in floodwater. The study area is located in Ghana, West Africa. Even though Ghana is one of the most urbanized countries in Africa it has significant problems with water resources management and public health. While cholera is classified as endemic in Accra, the natural and human-made characteristics of the capital makes it prone to flooding. The results of the EAPI approach show that on one hand the concentration of pathogens in floodwater, and thus the risk of infection, decreases with the increase of the flood magnitude. On the other hand, larger floods can spread the pathogens further from the point source, threatening populations previously not identified as at risk by small-scale floods. The concept of EAPI is demonstrated for cholera but it can be extended to other waterborne diseases and also different pathways of exposure, requiring minimal adaptations. For future applications, better estimation of EAPI key components and improvement points are discussed and recommendations given for all the assessment steps.

Cryptosporidiosis outbreak in Amazonia, French Guiana, 2018

BACKGROUND

Cryptosporidiosis outbreaks in South America are poorly documented. In March 2018, 51 cases of cryptosporidiosis were reported in Maripasoula, a village located in a remote forest area along the border between Surinam and French Guiana.

METHOD

To identify the origin of the epidemic, we performed epidemiological, microbiological, and environmental investigations. Only the cases involving diarrhoea and Cryptosporidium-positive stool were considered as bona fide, while cases involving diarrhoea and close contact with a confirmed case were classified as "possible".

RESULTS

We identified 16 confirmed cases and 35 possible ones. Confirmed cases comprised nine children (median age of 18 months, range: 6-21), one immunocompromised adult and six soldiers. One child required a hospitalisation for rehydration. All 16 Cryptosporidium stools were PCR positive, and sequencing of the gp60 gene confirmed only one Cryptosporidium hominis subtype IbA10G2. Tap water consumption was the only common risk factor identified. Contamination of the water network with Cryptosporidium parvum subtype IIdA19G2 was found.

CONCLUSION

Water quality is a major public health issue in Amazonian French Guiana, especially for population at risk (children, people with comorbidity, travelers). For them, alternative water supply or treatment should be implemented.

Maternal knowledge, attitude, and practice regarding diarrhoea and waterborne diseases in rural districts of Karbala, Iraq

OBJECTIVES

To assess knowledge, attitude, and practice (KAP), of rural mothers in Karbala, Iraq towards prevention and home management of diarrhoeal diseases among their children, in relation to water sanitation and personal hygiene.

METHODS

A cross-sectional study was conducted during the period from June to October 2016. Two hundred and five mothers of children under 5 years age living in two villages of Alhusainya district of Karbala were interviewed regarding their KAP on diarrhoea and waterborne diseases.

RESULTS

The overall mean score of the participants' KAP (out of 100) was 52.74 ± 9.69 with a range of 27.00- 81.00. The majority of the respondents, (n=159 (77.6%), had low KAP, and the mean score of attitude and practice (AP) was 56.98 ± 13.82 with a range of 12.50 - 93.75. More than half 116(56.6%) had weak AP. There was a significant association between the KAP score with that of AP. The KAP score and AP score were significantly lower in young mothers and those with lower education. One hundred seventeen (57%) participants claimed that television and radio were the main sources of their health information.

CONCLUSIONS

Mothers in rural areas in Karbala, especially the young and those with low education had low KAP and AP towards diarrhoea and waterborne diseases, and that there was a significant association between the two variables. Television and radio, and to a lesser extent the health centres were the main sources of knowledge.

Drinking Water Consumption Patterns among Private Well Users in Ontario: Implications for Exposure Assessment of Waterborne Infection

Understanding the water consumption patterns within a specific population informs development of increasingly accurate, spatially specific exposure and/or risk assessment of waterborne infection. The current study examined the consumption patterns of private well users in Ontario while considering potentially influential underlying sociodemographics, household characteristics, and experiential factors. A province-wide online survey was circulated between May and August 2018 (n = 1,162). Overall, 81.5% of respondents reported daily well water consumption (i.e., tap water). Results indicate a mean daily well water consumption rate of 1,132 mL/day (SD = 649 mL/day) among well water consumers. Gender was significantly associated with well water consumption, with higher consumption rates found among female respondents. The experience of acute gastrointestinal illness (AGI) symptoms or diagnosis in the past 12 months did not impact the volume of water consumed, suggesting that experiencing previous AGI does not decrease consumption volumes, and therefore exposure over time. Significantly higher rates of well water consumption were found among respondents who reported previous testing or ongoing water treatment. Approximately 45.5% of survey respondents who stated that they do not consume well water selected bottled water as their primary household drinking water supply. Bottled water consumption was also not associated with previous AGI experiences. Findings will inform future quantitative microbial risk assessments associated with private well water use by providing spatially and demographically specific estimates of well water consumption.

Trends of potential waterborne diseases at different health facilities in Bamboutos Division, West Region, Cameroon: a retrospective appraisal of routine data from 2013 to 2017

Many Cameroonian cities lack access to potable drinking water where populations rely on alternative water sources of doubtful quality. This study aimed at describing the trends and patterns of waterborne diseases (WBDs) reported in some health facilities in Bamboutos Division between 2013 and 2017 as baseline data towards understanding the profile of WBDs in this area. A retrospective review of clinical data kept on patients who visited the main health facilities in Bamboutos Division from January 2013 to December 2017 was conducted. Overall, 39.1% (n = 8,124) of total patients were positive for at least one WBD. Categories of WBDs were dysenteries (18.6%), gastroenteritis (4.2%), viral hepatitis (0.2%) and typhoid was the most preponderant (24.4%). The most affected age groups were those above 24 years but significant differences were observed only in 2013 and 2017. Distribution of potential WBDs was locality dependent. The highest prevalence of typhoid fever was recorded in Bameboro (35.4%), dysenteries in Bamedjinda (20.4%) and gastroenteritis (17.3%) in Bamekoumbou. The study shows very high overall prevalence of WBDs in some localities which could be considered as 'hotspots' of WBDs in Bamboutos. This suggests the urgent need for setting up measures to tackle the challenges of potable drinking water supply.

Investment in drinking water and sanitation infrastructure and its impact on waterborne diseases dissemination: The Brazilian case

Investment in sanitation and drinking water infrastructure is essential for universal access to these services in developing countries. Universal coverage of water and sanitation services (WSS) can prevent the dissemination of waterborne diseases and mitigate their adverse effects. These diseases are responsible for many deaths worldwide, especially among the disadvantaged population and children. A causal effect can be established between WSS investment and hospital admissions due to waterborne diseases. Therefore, we considered an innovative network-DEA approach that models the link between serially connected subsystems (upstream investment and downstream hospitalizations). This approach allowed us: to measure the efficiency of both subsystems; estimate the amount of (efficient) investment necessary to universalize the access to proper WSS infrastructure; and mitigate hospital admissions due to waterborne diseases. We used the Brazil case study to test our model. On average, Brazilian states could increase the number of people not requiring hospitalizations due to waterborne diseases by 157 thousand per R$100 million invested in sanitation and 26 thousand per R$100 million invested in drinking water. Our results suggest that relatively small (efficient) investment in those two infrastructure types has a massive impact on hospitalizations. This impact would be more significant than the investment in WSS coverage. Therefore, if safely managed, WSS would cover all citizens, and Brazil would come closer to developed countries.

Estimate of Burden and Direct Healthcare Cost of Infectious Waterborne Disease in the United States

Provision of safe drinking water in the United States is a great public health achievement. However, new waterborne disease challenges have emerged (e.g., aging infrastructure, chlorine-tolerant and biofilm-related pathogens, increased recreational water use). Comprehensive estimates of the health burden for all water exposure routes (ingestion, contact, inhalation) and sources (drinking, recreational, environmental) are needed. We estimated total illnesses, emergency department (ED) visits, hospitalizations, deaths, and direct healthcare costs for 17 waterborne infectious diseases. About 7.15 million waterborne illnesses occur annually (95% credible interval [CrI] 3.88 million–12.0 million), results in 601,000 ED visits (95% CrI 364,000–866,000), 118,000 hospitalizations (95% CrI 86,800–150,000), and 6,630 deaths (95% CrI 4,520–8,870) and incurring US $3.33 billion (95% CrI 1.37 billion–8.77 billion) in direct healthcare costs. Otitis externa and norovirus infection were the most common illnesses. Most hospitalizations and deaths were caused by biofilm-associated pathogens (nontuberculous mycobacteria, Pseudomonas, Legionella), costing US $2.39 billion annually.

Infectivity of Norovirus GI and GII from Bottled Mineral Water during a Waterborne Outbreak, Spain

During a waterborne outbreak of norovirus in Spain, we estimated 50% illness doses for a group of exposed (secretor) persons to be 556 (95% CI 319–957) genome copies/day for norovirus GI and 2,934 (95% CI 1,683–5,044) genome copies/day for norovirus GII. Use of a propidium monoazide viability assay reduced these values.

Effects of heavy rainfall on waterborne disease hospitalizations among young children in wet and dry areas of New Zealand

Heavy rainfall is associated with increased risk of waterborne disease. However, it is not known whether the risk increment differs between wet and dry regions. We examined this question in New Zealand, which has a wide geographical variation of annual rainfall totals (10^th-90^th percentile difference ≥3000 mm). We conducted a nested case-crossover study within a prospective child cohort (born in 2009-2010) for assessing transient health effects when modified by longitudinal exposures to rainfall. Short-term heavy rainfall effects on hospitalizations due to enteric bacterial and viral infectious causes at lag of 0-14 days were assessed using a Cox regression model adjusted for daily temperature, relative humidity and evapotranspiration. We derived quantiles of time-weighted long-term rainfall levels at the children's homes and these were added as an interaction term to the short-term effect model. Hospitalization risks were higher two days after heavy rainfall days (hazard ratio [95% confidence interval]: 1.73 [1.10-2.70]). The lowest-observable-adverse-effect-level was detected at the 94^th percentile of daily rainfall total. Hospital admissions 1-2 days after heavy rainfall increased most in locations with the lowest and highest long-term rainfall. An interaction of this kind between short-term weather and long-term climate has not been reported previously. It is relevant to climate change risk assessments given global projections of increasing intensity of precipitation, against a background of more severe, and possibly more frequent, droughts and flooding.

Rapid Detection Methods for Bacterial Pathogens in Ambient Waters at the Point of Sample Collection: A Brief Review

The world is currently facing a serious health burden of waterborne diseases, including diarrhea, gastrointestinal diseases, and systemic illnesses. The control of these infectious diseases ultimately depends on the access to safe drinking water, properly managed sanitation, and hygiene practices. Therefore, ultrasensitive, rapid, and specific monitoring platforms for bacterial pathogens in ambient waters at the point of sample collection are urgently needed. We conducted a literature review on state-of-the-art research of rapid in-field aquatic bacteria detection methods, including cell-based methods, nucleic acid amplification detection methods, and biosensors. The detection performance, the advantages, and the disadvantages of the technologies are critically discussed. We envision that promising monitoring approaches should be automated, real-time, and target-multiplexed, thus allowing comprehensive evaluation of exposure risks attributable to waterborne pathogens and even emerging microbial contaminants such as antibiotic resistance genes, which leads to better protection of public health.

Survival time of Leptospira kirschneri serovar Grippotyphosa under different environmental conditions

Leptospirosis is a re-emerging zoonotic disease of high medical importance that affects humans worldwide. Humans or animals acquire an infection with pathogenic leptospires either by direct contact with infected animals or by indirect contact to contaminated environment. Survival of Leptospira spp. in the environment after having been shed via animal urine is thus a key factor to estimate the risk of infection, but not much is known about the tenacity of pathogenic leptospires. Here, the survival time of both a laboratory strain and a field strain of L. kirschneri serovar Grippotyphosa in animal urine and their tenacity while drying was investigated and compared at different temperatures (15°C-37°C). Leptospira spp. are also often found in rivers and ponds. As the infection risk for humans and animals also depends on the spreading and survival of Leptospira spp. in these environments, the survival of L. kirschneri serovar Grippotyphosa was investigated using a 50-meter-long hose system simulating a water stream. Both strains did not survive in undiluted cattle or dog urine. Comparing different temperatures and dilution media, the laboratory strain survived the longest in diluted cattle urine with a slightly alkaline pH value (3 days), whilst the field strain survived in diluted dog urine with a slightly acid pH value up to a maximum of 24 h. Both strains did not survive drying on a solid surface. In a water stream, leptospires were able to move faster or slower than the average velocity of the water due to their intrinsic mobility but were not able to survive the mechanical damage caused by running water in the hose system. From our results we conclude, that once excreted via animal urine, the leptospires immediately need moisture or a water body to survive and stay infectious.

Water Management for Construction: Evidence for Risk Characterization in Community and Healthcare Settings: A Systematic Review

Construction activities are a known risk contributing to the growth and spread of waterborne pathogens in building water systems. The purpose of the study is to integrate evidence for categorizing construction activity risk factors contributing to waterborne disease in community and healthcare settings, establish severity of such risk factors and identify knowledge gaps. Using a systematic review, the inclusion criteria were: 1) studies with disease cases suspected to be associated with construction activities and waterborne pathogens, and 2) active construction work described in a community or healthcare setting. Each construction activity risk factor was correlated across all studies with the number of disease cases and deaths to establish risk severity. The eligibility review and quantitative synthesis yielded 31 studies for inclusion (community, n = 7 and healthcare, n = 24). From 1965 to 2016, a total of 894 disease cases inclusive of 112 deaths were associated with nine construction activity risk factors and waterborne pathogens. The present study findings support the need for building owners, water management teams and public health professionals to address construction activity risk factors and the analysis of current knowledge deficiencies within the scope of an ongoing water management program. The impact of construction activities on waterborne disease is preventable and should no longer be considered incidental nor accidental.

Projected local rain events due to climate change and the impacts on waterborne diseases in Vancouver, British Columbia, Canada

BACKGROUND

Climate change is increasing the number and intensity of extreme weather events in many parts of the world. Precipitation extremes have been linked to both outbreaks and sporadic cases of waterborne illness. We have previously shown a link between heavy rain and turbidity to population-level risk of sporadic cryptosporidiosis and giardiasis in a major Canadian urban population. The risk increased with 30 or more dry days in the 60 days preceding the week of extreme rain. The goal of this study was to investigate the change in cryptosporidiosis and giardiasis risk due to climate change, primarily change in extreme precipitation.

METHODS

Cases of cryptosporidiosis and giardiasis were extracted from a reportable disease system (1997-2009). We used distributed lag non-linear Poisson regression models and projections of the exposure-outcome relationship to estimate future illness (2020-2099). The climate projections are derived from twelve statistically downscaled regional climate models. Relative Concentration Pathway 8.5 was used to project precipitation derived from daily gridded weather observation data (~ 6 × 10 km resolution) covering the central of three adjacent watersheds serving metropolitan Vancouver for the 2020s, 2040s, 2060s and 2080s.

RESULTS

Precipitation is predicted to steadily increase in these watersheds during the wet season (Oct. -Mar.) and decrease in other parts of the year up through the 2080s. More weeks with extreme rain (>90th percentile) are expected. These weeks are predicted to increase the annual rates of cryptosporidiosis and giardiasis by approximately 16% by the 2080s corresponding to an increase of 55-136 additional cases per year depending upon the climate model used. The predicted increase in the number of waterborne illness cases are during the wet months. The range in future projections compared to historical monthly case counts typically differed by 10-20% across climate models but the direction of change was consistent for all models.

DISCUSSION

If new water filtration measures had not been implemented in our study area in 2010-2015, the risk of cryptosporidiosis and giardiasis would have been expected to increase with climate change, particularly precipitation changes. In addition to the predicted increase in the frequency and intensity of extreme precipitation events, the frequency and length of wet and dry spells could also affect the risk of waterborne diseases as we observed in the historical period. These findings add to the growing evidence regarding the need to prepare water systems to manage and become resilient to climate change-related health risks.

Fecal pollution source tracking and thalassogenic diseases: The temporal-spatial concordance between maximum concentrations of human mitochondrial DNA in seawater and Hepatitis A outbreaks among a coastal population

Fecal pollution source tracking (FST) studies the origin of fecal contamination and promotes action to eliminate it to improve human health and environmental sustainability. This work presents the temporal and spatial relations of human mitochondrial DNA (HmtDNA), fecal coliforms (FC) and live microbial biomass (ATP) in seawater during a hepatitis A outbreak among a human coastal population. The study area is approximately 100 km along the coastline of the Biobío Region in the southeastern Pacific (Humboldt Current System, Chile). Total data from the swash zone from summer 2015 to autumn 2016 show there were significant positive log-log correlations between FC and HmtDNA (R = 0.32) and ATP (R = 0.31). These correlations were highest during the austral spring of 2015 (R = 0.53 and 0.58 respectively), when HmtDNA also correlated significantly with ATP (R = 0.86). Maximum average values of the parameters measured in this season showed a temporal-spatial concordance with the peak in the number of hepatitis A cases among the nearby coastal population. FC correlated significantly with HmtDNA (R = 0.98) in the water column of the coastal zone close to Concepción Bay during the austral summer of 2016 and in the swash zone of the bay (R = 0.68) throughout the study period. Hepatitis A virus (HAV) has also been detected in organisms and seawater in Concepción Bay, which is consistent with the high incidence of hepatitis A among the coastal population. The concordance between human fecal pollution in the study area and a seasonal hepatitis A outbreak strongly suggests that HmtDNA and its relation with FC and ATP in the coastal zone of marine environments can be used as a proxy to evaluate the risk of outbreaks of thalassogenic diseases.

Assessment of two behavioural models (HBM and RANAS) for predicting health behaviours in response to environmental threats: Surface water flooding as a source of groundwater contamination and subsequent waterborne infection in the Republic of Ireland

Extreme weather events (EWEs) are increasing in frequency, posing a greater risk of adverse human health effects. As such, developing sociological and psychological based interventions is paramount to empowering individuals and communities to actively protect their own health. Accordingly, this study compared the efficacy of two established social-cognitive models, namely the Health Beliefs Model (HBM) and Risks-Attitudes-Norms-Abilities-Self-regulation (RANAS) framework, in predicting health behaviours following EWEs. Surface water flooding was used as the exemplar EWE in the current study, due to the increasing incidence of these events in the Republic of Ireland over the past decade. Levels of prior experience with flooding were considered for analyses and comparative tools included a number of variables predicting health behaviours and intervention potential scores (i.e. measure of impact of targeting each model element). Results suggest that the RANAS model provides a robust foundation for designing interventions for any level of experience with an extreme weather event, however, use of the simpler HBM may be more cost-effective among participants unacquainted with an EWE and in relatively infrequent health threat scenarios. Results provide an evidence base for researchers and policymakers to appropriately engage with populations about such threats and successfully promote spatiotemporally appropriate health behaviours in a changing climate.

Identifying waterborne disease prone areas using geospatial approach along the right bank of Yamuna River in Delhi

This paper presents a spatial risk analysis of waterborne diseases using analytical hierarchy process that rely on geographical information system (GIS)-automated techniques. We selected nine parameters for assessing waterborne diseases prone areas (WBDP). All the weighted parameter layers were integrated to obtain WBDP map. Of the total WBDP area, 42% area was found under medium category, 34% and 24% area under high and low category, respectively. We have also empirically analysed the factors influencing WBDP areas using regression model. Results revealed that explanatory variables like purification of water, washing hand before drinking and eating, and Surface Water Quality Index (SWQI) are the most influential and positively associated while dipping hand in the vessel is negatively associated with the WBD. Further, WBDP areas were validated by analysing their relationship with the actual incidences of WBD(s). Our study may prove to be beneficial for managing and formulating guidelines for the WBDP areas in similar geographical regions. Abbreviations: GIS: Geographical information system; WBDP: Water borne diseases prone areas; SWQI: Surface water quality index; WBD: Water borne Disease; MDG: Millennium Development Goal; AHP: Analytical hierarchical process; GPS: Global Positioning System; NCR: National Capital Region; IDW: Inverse distance weighted; pH: Potential of Hydrogen; TDS: Total dissolved solid; COD: Chemical Oxygen Demand; BOD: Biochemical Oxygen Demand; TA: Total alkalinity; TH: Total Hardness; Cl: Chlorination; SO4: Sulphate, NO3: Nitrate; FL: Floride; ICMR: Indian Council of Medical Research; ISB: Indian Standards Bureau; RW: Relative weights; WQI: Water Quality Index; DJB: Delhi Jal Board; MDG: Millennium Development Goals; GWQI: Ground Water Quality Index; MCD: Municipality Corporation of Delhi; CPCB: Central Pollution Control Board.

Outbreak of Cholera Due to Cyclone Kenneth in Northern Mozambique, 2019

Cyclone Kenneth was the strongest in the recorded history of the African continent. It landed in the Cabo Delgado province in northern Mozambique on 25 April 2019, causing 45 deaths, destroying approximately 40,000 houses, and leaving 374,000 people in need for assistance, most at risk of acquiring waterborne diseases such as cholera. This short article aims to explain how the resulting cholera outbreak occurred and the response by the government and partner organizations. The outbreak was declared on 2 May 2019, after 14 cases were recorded in Pemba city (11 cases) and the Mecúfi district (3 cases). The disease spread to Metuge, and by the 12th of May 2019, there were 149 cases. Aware of the risk of an outbreak of cholera, the government and partners took immediate action as the cyclone ended, adapting the Cholera Response Plan for Beira, revised after the experience with cyclone Idai (4–21 March 2019). The response relevant to cholera epidemics consisted of social mobilization campaigns for prevention, establishment of treatment centers and units, coordination to improve of water, sanitation and hygiene, and surveillance. By 26 May 2019, 252,448 people were immunized in the area affected by cyclone Kenneth. The recovery process is ongoing but the number of new cases has been reducing, seemingly due to an efficient response, support of several organizations and collaboration of the civil society. Future interventions shall follow the same model of response but the government of Mozambique shall keep a contingency fund to manage disasters such as cyclone Idai and Kenneth. The unlikeliness of two cyclones (Idai and Kenneth) within two months after decades without such kind of phenomena points towards the problem of climate change, and Mozambique needs to prepare effective, proven response plans to combat outbreaks of waterborne diseases due to cyclones.

Water uses, treatment, and sanitation practices in rural areas of Chandigarh and its relation with waterborne diseases

Availability of clean water and adequate sanitation facilities are the principal measures for limiting various waterborne diseases. These basic amenities are critical for health and sustainable socio-economic development. This study attempted to assess the status of water and sanitation facilities and practices of the people living in rural areas of Chandigarh including awareness about the waterborne diseases. The community-based cross-sectional study design was adopted having 300 households across 12 villages of city Chandigarh. A standardized interview schedule was used to collect information related to water uses, storage, water treatment options, water conservation practices, personal hygiene, knowledge about waterborne diseases, and government schemes. The interview schedule was administered with the head of the family as a study approach during the door-to-door survey. Households in rural Chandigarh have municipal water supply for drinking as well as other domestic purposes. The mean per capita water usage was 67 ± 13.4 l. Most (68.6%) of the study participants reported that they do not treat water before drinking and store it in plastic bottles or bucket (58%). The survey shows that 97% of the household had functional toilets in their premises, remaining reported lack of finances, and space for construction as major barriers. Regarding personal hygiene, 83% of respondents wash hands with soap and rest used only water or ash. Observations made under the study highlighted the need to create awareness regarding the role of water and sanitation practices on health including knowledge about various government schemes to improve water quality, sanitation, and hygiene practices for better health.

Prevalence of water-related diseases and groundwater (drinking-water) contamination in the suburban municipality of Mont Ngafula, Kinshasa (Democratic Republic of the Congo)

An epidemiological survey conducted among users of water points and medical institutions in the N'djili Kilambu neighborhood of Kinshasa in Democratic Republic of the Congo, indicates that waterborne diseases have already affected more than 60% of the patients admitted to local clinics between 2013 and 2017. In order to raise public and political awareness about this hazardous health issue resulting from the lack of safely managed sanitation systems, this study investigates the microbial quality of drinking water from local water resources. Water samples were collected from nine wells and streams used as drinking sources, and analyzed for Fecal Indicator Bacteria (FIB), including Escherichia coli, Enterococcus, and Total Coliforms. Physicochemical parameters (pH, electrical conductivity, O₂, and soluble ions (Na⁺, K⁺, PO₄^3-, SO₄^2-, NO₃^-, NO₂^-) were also analyzed. Except for NO₃^- and NO₂^-, the average concentrations of the physicochemical parameters and dissolved ions generally meet the guidelines for drinking/domestic water quality. By contrast, the results reveal high levels of FIB in the water samples collected during both dry and wet seasons. The contamination is significantly higher during the wet season compared to dry season, due to increased runoff, open defecation practices, and more frequent overflow of onsite sanitation systems and septic tanks.

[Relationship of subclinical hypothyroidism and goiter with the origin of water consumed by a population of the Buenos Aires suburbs]

Subclinical hypothyroidism (SH), elevation of the level of thyrotrophin with normal thyroid hormones, along with goiter (glandular size > 25g), increased in recent decades. In order to relate the prevalence of goiter and SH with the consumption of groundwater, as a population etiological risk factor, we analyzed 879 clinical histories from a medical center in the city of Glew in the South Buenos Aires suburbs. The population was studied according to age (20 to 60 and 12 to 19 years) and type of water consumed (potable water or groundwater). Groundwater was consumed by 70.5% of the group from 20 to 60 years old (n = 559, 79.9% women) and by 66.3% of the group from 12 to 19 years old (n = 57, 81.4% women In the group of 20 to 60 years, the prevalence of SH in potable water and groundwater users was 1% and 57.8% (p < 0.0001) and the goiter rate of 3.8% and 38.9% (p < 0.0001) respectively; with an attributable risk to groundwater of 57% for HS, and 35% for goiter In the group of 12 to 19 years, the prevalence of SH was 6.9% and 52.6% (p < 0.0001) and goiter 13.8% and 77.2% for the water and groundwater groups (p > 0.0001) respectively, with an attributable risk of 46% for HS y 61% for goiter. The physicochemical analysis showed the presence of nitrates in the range of 24 to 83 mg/l in groundwater and absence in potable water. The increased prevalence of HS and goiter could be due to the thyroid disrupting action of nitrates.

Waterborne Infections in Reunion Island, 2010-2017

Gram-negative bacilli Vibrio spp., Aeromonas spp., and Shewanella spp. are a major cause of severe waterborne infection. The aim of this study was to assess the clinical and microbiological characteristics and prognosis of patients hospitalized in Reunion Island for a waterborne infection. This retrospective study was conducted in the two university hospitals of Reunion Island between January 2010 and March 2017. Patients diagnosed with a Vibrio, Aeromonas, or Shewanella infection were evaluated. Over the study period, 112 aquatic strains were isolated at Reunion Island: Aeromonas spp. were found in 91 patients (81.3%), Shewanella spp. in 13 patients (11.6%), and Vibrio spp. in eight patients (7.2%). The in-hospital mortality rate was 11.6%. The main sites of infection were skin and soft tissue (44.6%) and the abdomen (19.6%). Infections were polymicrobial in 70 cases (62.5%). The most commonly prescribed empiric antibiotic regimen was amoxicillin-clavulanate (34.8%). Eighty-four percent of the aquatic strains were resistant to amoxicillin-clavulanate and more than > 95% were susceptible to third or fourth generation cephalosporins and fluoroquinolones. After multivariate analysis, the only independent risk factor of in-hospital mortality was the presence of sepsis (P < 0.0001). In Reunion Island, the most commonly isolated aquatic microorganisms were Aeromonas spp. Sepsis caused by aquatic microorganisms was frequent (> 50%) and associated with higher in-hospital mortality. This study suggests that empiric antibiotic regimens in patients with sepsis or septic shock caused by suspected aquatic microorganisms (tropical climate, skin lesion exposed to seawater…) should include broad-spectrum antibiotics (third or fourth generation cephalosporins).

Waterborne Disease Outbreak Detection: A Simulation-Based Study

Waterborne disease outbreaks (WBDOs) remain a public health issue in developed countries, but to date the surveillance of WBDOs in France, mainly based on the voluntary reporting of clusters of acute gastrointestinal infections (AGIs) by general practitioners to health authorities, is characterized by low sensitivity. In this context, a detection algorithm using health insurance data and based on a space–time method was developed to improve WBDO detection. The objective of the present simulation-based study was to evaluate the performance of this algorithm for WBDO detection using health insurance data. The daily baseline counts of acute gastrointestinal infections were simulated. Two thousand simulated WBDO signals were then superimposed on the baseline data. Sensitivity (Se) and positive predictive value (PPV) were both used to evaluate the detection algorithm. Multivariate regression was also performed to identify the factors associated with WBDO detection. Almost three-quarters of the simulated WBDOs were detected (Se = 73.0%). More than 9 out of 10 detected signals corresponded to a WBDO (PPV = 90.5%). The probability of detecting a WBDO increased with the outbreak size. These results underline the value of using the detection algorithm for the implementation of a national surveillance system for WBDOs in France.

A Perspective on the Global Pandemic of Waterborne Disease

Waterborne diseases continue to take a heavy toll on the global community, with developing nations, and particularly young children carrying most of the burden of morbidity and mortality. Starting with the historical context, this article explores some of the reasons why this burden continues today, despite our advances in public health over the past century or so. While molecular biology has revolutionized our abilities to define the ecosystems and etiologies of waterborne pathogens, control remains elusive. Lack of basic hygiene and sanitation, and failing infrastructure, remain two of the greatest challenges in the global fight against waterborne disease. Emerging risks continue to be the specter of multiple drug resistance and the ease with which determinants of virulence appear to be transmitted between strains of pathogens, both within and outside the human host.

Surface water flooding, groundwater contamination, and enteric disease in developed countries: A scoping review of connections and consequences

Significant volumes of research over the past four decades has sought to elucidate the social, infrastructural, economic, and human health effects of climate change induced surface flooding. To date, epidemiological and public health studies of flooding events have focused on mental health effects, vector-borne diseases, and infectious enteric disease due to floodwater contact (i.e. typically low consumption rates). The inherent nature of groundwater (i.e. out of sight, out of mind) and the widely held belief that aquifers represent a pristine source of drinking water due to natural attenuation may represent the "perfect storm" causing direct consumption of relatively large volumes of surface flood-contaminated groundwater. Accordingly, the current study sought to systematically identify and synthesize all available peer-reviewed literature pertaining to the nexus between surface flooding, groundwater contamination and human gastroenteric outcomes. Just 14 relevant studies were found to have been published during the period 1980-2017, thus highlighting the fact that this potentially significant source of climate-related exposure to environmental infection has remained understudied to date. Studies differed significantly in terms of type and data reporting procedures, making it difficult to discern clear trends and patterns. Approximately 945 confirmed cases of flood-related enteric disease were examined across studies; these concurred with almost 10,000 suspected cases, equating to approximately 20 suspected cases per confirmed case. As such, no regional, national or global estimates are available for the human gastrointestinal health burden of flood-related groundwater contamination. In light of the demonstrable public health significance of the concurrent impacts of groundwater susceptibility and climate change exacerbation, strategies to increase awareness about potential sources of contamination and motivate precautionary behaviour (e.g. drinking water testing and treatment, supply interruptions) are necessary. Mainstreaming climate adaptation concerns into planning policies will also be necessary to reduce human exposure to waterborne sources of enteric infection.

Estimate of incidence and cost of recreational waterborne illness on United States surface waters

BACKGROUND

Activities such as swimming, paddling, motor-boating, and fishing are relatively common on US surface waters. Water recreators have a higher rate of acute gastrointestinal illness, along with other illnesses including respiratory, ear, eye, and skin symptoms, compared to non-water recreators. The quantity and costs of such illnesses are unknown on a national scale.

METHODS

Recreational waterborne illness incidence and severity were estimated using data from prospective cohort studies of water recreation, reports of recreational waterborne disease outbreaks, and national water recreation statistics. Costs associated with medication use, healthcare provider visits, emergency department (ED) visits, hospitalizations, lost productivity, long-term sequelae, and mortality were aggregated.

RESULTS

An estimated 4 billion surface water recreation events occur annually, resulting in an estimated 90 million illnesses nationwide and costs of $2.2- $3.7 billion annually (central 90% of values). Illnesses of moderate severity (visit to a health care provider or ED) were responsible for over 65% of the economic burden (central 90% of values: $1.4- $2.4 billion); severe illnesses (result in hospitalization or death) were responsible for approximately 8% of the total economic burden (central 90% of values: $108- $614 million).

CONCLUSION

Recreational waterborne illnesses are associated with a substantial economic burden. These findings may be useful in cost-benefit analysis for water quality improvement and other risk reduction initiatives.

Analysis of Health Indicators in Two Rural Communities on the Colombian Caribbean Coast: Poor Water Supply and Education Level Are Associated with Water-Related Diseases

Water-related diseases are closely linked with drinking water, sanitation, and hygiene (WASH) indicators, socioeconomic status, education level, or dwelling's conditions. Developing countries exhibit a particular vulnerability to these diseases, especially rural areas and urban slums. This study assessed socioeconomic features, WASH indicators, and water-related diseases in two rural areas of the Colombian Caribbean coast. Most of this population did not finish basic education (72.3%, N = 159). Only one of the communities had a water supply (aqueduct), whereas the other received water via an adapted tanker ship. No respondents reported sewage services; 92.7% (N = 204) had garbage service. Reported cases of diarrhea were associated with low education levels (P = 2.37 × 10-9) and an unimproved drinking water supply (P = 0.035). At least one fever episode was reported in 20% (N = 44) of dwellings, but the cases were not related to any indicator. The Aedes/House index (percentage of houses that tested positive for Aedes larvae and/or pupae) was 69%, the container index (percentage of water-holding containers positive for Aedes larvae or pupae) 29.4%, and the Breteau index (number of positive containers per 100 houses in a specific location) was three positive containers per 100 inspected houses. The presence of positive containers was associated with the absence of a drinking water supply (P = 0.04). The community with poorer health indicators showed greater health vulnerability conditions for acquisition of water-related diseases. In summary, water supply and educational level were the main factors associated with the presence of water-related diseases in both communities.

Destination specific risks of acquisition of notifiable food- and waterborne infections or sexually transmitted infections among Finnish international travellers, 1995-2015

BACKGROUND

Overnight international travels made by Finns more than doubled during 1995-2015. To estimate risks and observe trends of travel-related notifiable sexually transmitted and food- and water-borne infections (STIs and FWIs) among travellers, we analysed national reports of gonorrhoea, syphilis, hepatitis A, shigellosis, campylobacteriosis and salmonellosis cases and related them to travel statistics.

METHOD

Cases notified as travel-related to the Finnish infectious diseases register were used as numerators and overnight stays of Statistics Finland surveys as denominator. We calculated overall risks (per 100,000 travellers) and assessed trends (using regression model) in various geographic regions.

RESULTS

Of all travel-related cases during 1995-2015, 2304 were STIs and 70,929 FWIs. During 2012-2015, Asia-Oceania showed highest risk estimates for gonorrhoea (11.0; 95%CI, 9.5-13), syphilis (1.4; 0.93-2.1), salmonellosis (157; 151-164), and campylobacteriosis (135; 129-141), and Africa for hepatitis A (4.5; 2.5-7.9), and shigellosis (35; 28-43). When evaluating at country level, the highest risks of infections was found in Thailand, except for hepatitis A ranking Hungary the first. During 2000-2011, significantly decreasing trends occurred for most FWIs particularly in the European regions and for STIs in Russia-Baltics.

CONCLUSIONS

Our findings can be used in targeting pre-travel advice, which should also cover those visiting Thailand or European hepatitis A risk areas.

Prevalence and direct costs of emergency department visits and hospitalizations for selected diseases that can be transmitted by water, United States

National emergency department (ED) visit prevalence and costs for selected diseases that can be transmitted by water were estimated using large healthcare databases (acute otitis externa, campylobacteriosis, cryptosporidiosis, Escherichia coli infection, free-living ameba infection, giardiasis, hepatitis A virus (HAV) infection, Legionnaires' disease, nontuberculous mycobacterial (NTM) infection, Pseudomonas-related pneumonia or septicemia, salmonellosis, shigellosis, and vibriosis or cholera). An estimated 477,000 annual ED visits (95% CI: 459,000-494,000) were documented, with 21% (n = 101,000, 95% CI: 97,000-105,000) resulting in immediate hospital admission. The remaining 376,000 annual treat-and-release ED visits (95% CI: 361,000-390,000) resulted in $194 million in annual direct costs. Most treat-and-release ED visits (97%) and costs ($178 million/year) were associated with acute otitis externa. HAV ($5.5 million), NTM ($2.3 million), and salmonellosis ($2.2 million) were associated with next highest total costs. Cryptosporidiosis ($2,035), campylobacteriosis ($1,783), and NTM ($1,709) had the highest mean costs per treat-and-release ED visit. Overall, the annual hospitalization and treat-and-release ED visit costs associated with the selected diseases totaled $3.8 billion. As most of these diseases are not solely transmitted by water, an attribution process is needed as a next step to determine the proportion of these visits and costs attributable to waterborne transmission.

Waterborne disease outbreak detection: an integrated approach using health administrative databases

Hundreds of waterborne disease outbreaks (WBDO) of acute gastroenteritis (AGI) due to contaminated tap water are reported in developed countries each year. Such outbreaks are probably under-detected. The aim of our study was to develop an integrated approach to detect and study clusters of AGI in geographical areas with homogeneous exposure to drinking water. Data for the number of AGI cases are available at the municipality level while exposure to tap water depends on drinking water networks (DWN). These two geographical units do not systematically overlap. This study proposed to develop an algorithm which would match the most relevant grouping of municipalities with a specific DWN, in order that tap water exposure can be taken into account when investigating future disease outbreaks. A space-time detection method was applied to the grouping of municipalities. Seven hundred and fourteen new geographical areas (groupings of municipalities) were obtained compared with the 1,310 municipalities and the 1,706 DWN. Eleven potential WBDO were identified in these groupings of municipalities. For ten of them, additional environmental investigations identified at least one event that could have caused microbiological contamination of DWN in the days previous to the occurrence of a reported WBDO.

Waterparks are high risk for cryptosporidiosis: A case-control study in Victoria, 2015

BACKGROUND

An increase in notifications of cryptosporidiosis was observed in Victoria between March and April 2015. Cases mostly resided in one metropolitan region and hypothesis-generating interviews identified common exposures to aquatic facilities. We conducted a case-control study to determine exposure source(s) and facilitate control measures.

METHODS

Laboratory-confirmed cases of cryptosporidiosis from the region of interest notified between 1 March and 23 April 2015 were included. Controls residing in the same region were recruited from participants in a population health survey and frequency matched (2 per case) by age group. Details of exposure to potential risk factors were collected using a standardised telephone questionnaire for the 14-days prior to illness for cases, and an analogous exposure period for controls. Univariable and multivariable logistic regression were used to determine risk factors associated with illness using STATA SE 13.1.

RESULTS

Thirty cases and 66 controls were included in the study. Half the cases were less than 12 years of age and 62% were female. Illness was most strongly associated with recreational water exposure at any waterpark (adjusted odds ratio (aOR)=73.5; 95% confidence interval (CI):6.74-802), and specifically at Victorian waterparks (aOR=45.6; 95% CI:5.20-399). Cases were linked with attendance at either a waterpark in the region or an adjacent region. As a result of this investigation, hyperchlorination was completed at identified facilities and swim hygiene information distributed.

CONCLUSION

This study reinforces the potential for recreational water facilities, particularly waterparks, to act as a transmission source of Cryptosporidium infections. Continued communication to patrons is required to ensure healthy swimming practice in Victorian aquatic facilities.

Association of water handling and child feeding practice with childhood diarrhoea in rural community of Southern Nepal

Diarrhoea is a major cause of childhood morbidity and mortality globally. While the childhood diarrhoea and its association with child feeding, and hygiene, hand washing and water treatment are studied elsewhere, the association of water handling and child feeding with childhood diarrhoea is an understudied area in Nepal. This study aimed to investigate the association of water handling and child feeding practice with childhood diarrhoea among children of one to five years of age in Southern, Nepal. A cross-sectional study was conducted in the Dhanusha district of Southern Nepal in 2013. A total of 284 mother-child pairs were selected using systemic random sampling. A four-week prevalence of childhood diarrhoea was reported using frequency distribution. The association of childhood diarrhoea with water handling and child feeding practices was ascertained using multiple logistic regressions after adjusting for potential confounders. The result of the study demonstrated that the four-week prevalence of childhood diarrhoea was 36.6%. Our finding showed that unsafe water handling practices were associated independently with childhood diarrhoea: untreated water (aOR 3.55; 95% CI: 1.13-11.10), uncovered water (aOR 2.14; 95% CI: 1.09-4.19). Similarly, partial breast feeding (aOR 4.35; 95% CI: 1.87-10.12) was also associated with higher odds of childhood diarrhoea. One third of children in Southern Nepal still had diarrhoea within the four weeks preceding the survey. As poor water handling and sub optimal infant feeding practice were major risk factors contributing to such a high burden of the disease, health promotion strategies such as promotion of safe water handling, improved hygiene and child feeding practices are recommended for the prevention of childhood diarrhoea in Southern Terai of Nepal.

Safe drinking water and waterborne outbreaks

The present work compiles a review on drinking waterborne outbreaks, with the perspective of production and distribution of microbiologically safe water, during 2000-2014. The outbreaks are categorised in raw water contamination, treatment deficiencies and distribution network failure. The main causes for contamination were: for groundwater, intrusion of animal faeces or wastewater due to heavy rain; in surface water, discharge of wastewater into the water source and increased turbidity and colour; at treatment plants, malfunctioning of the disinfection equipment; and for distribution systems, cross-connections, pipe breaks and wastewater intrusion into the network. Pathogens causing the largest number of affected consumers were Cryptosporidium, norovirus, Giardia, Campylobacter, and rotavirus. The largest number of different pathogens was found for the treatment works and the distribution network. The largest number of affected consumers with gastrointestinal illness was for contamination events from a surface water source, while the largest number of individual events occurred for the distribution network.

Association between heavy precipitation events and waterborne outbreaks in four Nordic countries, 1992-2012

We conducted a matched case-control study to examine the association between heavy precipitation events and waterborne outbreaks (WBOs) by linking epidemiological registries and meteorological data between 1992 and 2012 in four Nordic countries. Heavy precipitation events were defined by above average (exceedance) daily rainfall during the preceding weeks using local references. We performed conditional logistic regression using the four previous years as the controls. Among WBOs with known onset date (n = 89), exceedance rainfall on two or more days was associated with occurrence of outbreak, OR = 3.06 (95% CI 1.38-6.78), compared to zero exceedance days. Stratified analyses revealed a significant association with single household water supplies, ground water as source and for outbreaks occurring during spring and summer. These findings were reproduced in analyses including all WBOs with known outbreak month (n = 186). The vulnerability of single households to WBOs associated with heavy precipitation events should be communicated to homeowners and implemented into future policy planning to reduce the risk of waterborne illness.