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

Examining campylobacteriosis disease notification rates: Association with water supply characteristics

Campylobacter is the most frequent cause of bacterial enteric disease in New Zealand, often linked to food-borne transmission from contaminated fresh poultry. However, socioeconomic, agricultural, and environmental factors, including drinking water sources, also play a role in infections. About 15% of New Zealand residents rely on private water supplies, which are not regulated for water quality under the Water Services Act 2021. This situation poses a risk for waterborne transmission of Campylobacter. We analysed publicly notified cases of Campylobacter infection from 2015 to 2019 using Poisson regression models to evaluate the impact of water supply type, rurality, livestock density, and climate extremes on campylobacteriosis incidence. The results showed a significant association between private water supply in rural areas and increased campylobacteriosis incidence in high dairy density areas (Relative Risk (RR) = 2.21, 95% CI: 1.60-3.05). Higher dairy density was also linked to increased campylobacteriosis incidence, with low dairy density having an RR of 1.18 (95% CI: 1.04-1.34), medium density an RR of 1.17 (95% CI: 1.03-1.33), and high density an RR of 1.47 (95% CI: 1.28-1.69) in rural areas with private water supplies. These findings suggest that contaminated water may be a significant pathway for Campylobacter infection, indicating a potential need for additional support for private water users in rural areas.

The effects of rain and drought on incidence of enteric disease in Pennsylvania (2010-2019)

BACKGROUND

Campylobacter, nontyphoidal Salmonella, Cryptosporidium, and Giardia cause an estimated 1 million cases of domestically acquired waterborne diseases annually in the United States. Acute symptoms can include diarrhea and vomiting; however, these illnesses can result in longer term complications such as reactive arthritis, Guillan Barré syndrome and death, particularly in immunocompromised individuals. Precipitation and drought can plausibly increase the risk of enteric infections, but consensus in the literature is lacking.

OBJECTIVES

To determine the effects of rain and drought on weekly counts of reportable enteric illness (due to Salmonella, Campylobacter, Giardia, or Cryptosporidium) in Pennsylvania, US between 2010 and 2019.

METHODS

We obtained 10-years of data on confirmed illness from 66 Pennsylvania counties due to: Salmonella (9,924), Campylobacter (15,854), Giardia (4,537), and Cryptosporidium (4,017). A zero-inflated negative binomial model with random-intercept for county was used to assess the relationship between illnesses caused by these pathogens between 2010 and 2019, and weekly rain (cm) and Palmer Drought Severity Index (PDSI) values from the National Weather Service. The lag times that were tested, between illness and weather event, were chosen by calculating the cross correlation between the statewide average weekly rain and the statewide number of weekly cases.

RESULTS

A positive association was found between rain and counts of campylobacteriosis, salmonellosis, and giardiasis. An increase in prior wetness (PDSI value) was associated with increased incidence rates of cryptosporidiosis and campylobacteriosis. The relationship between rain and PDSI and illness varied by organism type.

DISCUSSION

Complex relationships exist between enteric disease and precipitation and prior environmental wetness. Our findings suggest that rainfall may be contributing to increased waterborne exposure. Further investigation is needed to explore these relationships with factors such as drinking water source, local geological conditions, presence of combined sewer overflows and agricultural activities, recreational water use and irrigation water sources to better elucidate important waterborne transmission pathways.

Climate change and waterborne diseases in temperate regions: a systematic review

Risk of waterborne diseases (WBDs) persists in temperate regions. The extent of influence of climate-related factors on the risk of specific WBDs in a changing climate and the projections of future climate scenarios on WBDs in temperate regions are unclear. A systematic review was conducted to identify specific waterborne pathogens and diseases prevalent in temperate region literature and transmission cycle associations with a changing climate. Projections of WBD risk based on future climate scenarios and models used to assess future disease risk were identified. Seventy-five peer-reviewed full-text articles for temperate regions published in the English language were included in this review after a search of Scopus and Web of Science databases from 2010 to 2023. Using thematic analysis, climate-related drivers impacting WBD risk were identified. Risk of WBDs was influenced mostly by weather (rainfall: 22% and heavy rainfall: 19%) across the majority of temperate regions and hydrological (streamflow: 50%) factors in Europe. Future climate scenarios suggest that WBD risk is likely to increase in temperate regions. Given the need to understand changes and potential feedback across fate, transport and exposure pathways, more studies should combine data-driven and process-based models to better assess future risks using model simulations.

Bacterial accumulation dynamics in runoff from extreme precipitation

Extreme precipitation can significantly influence the water quality of surface waters. However, the total amount of bacteria carried by rainfall runoff is poorly understood. Here, thirty rainfall scenarios were simulated by artificial rainfall simulators, with designed rainfall intensity ranging from 19.3 to 250 mm/h. The instantaneous concentration ranges of R2A, nutrient agar (NA) culturable bacteria, and viable bacteria in runoff depended on the types of underlying surfaces. The instantaneous bacterial concentrations in runoff generated by forest lands, grasslands and bare soil were: R2A culturable bacteria = 104.5-6.3, 104.5-6.1, 104.0-5.3 colony-forming units (CFU)/mL, NA culturable bacteria = 104.0-6.0, 103.9-5.8, 103.2-4.9 CFU/mL, and viable bacteria = 106.4-8.0, 107.0-8.9, 106.4-7.6 cells/mL. Based on the measured bacterial instantaneous concentration in runoff, cumulative dynamic models were established, and the maximum amount of culturable bacteria and viable bacteria entering water sources were estimated to be 109.38-11.31 CFU/m2 and 1011.84-13.25 cells/m2, respectively. The model fitting and the bacterial accumulation dynamics were influenced by the rainfall types (p < 0.01). Surface runoff from the underlying surface of forest lands and grasslands had a high microbial risk that persisted even during the "Drought-to-Deluge Transition". Bacterial accumulation models provide valuable insight for predicting microbial risks in catchments during precipitation and can serve as theoretical support for further ensuring the safety of drinking water under the challenge of climate change.

Short-term associations between precipitation and gastrointestinal illness-related hospital admissions: A multi-city study in Texas

The ongoing climate change crisis presents challenges to the global public health system. The risk of gastrointestinal illness (GI) related hospitalization increases following extreme weather events but is largely under-reported and under-investigated. This study assessed the association between precipitation and GI-related hospital admissions in four major cities in Texas. Daily data on GI-related hospital admissions and precipitation from 2004 to 2014 were captured from the Texas Department of State Health Services and the National Climate Data Center. Distributed lagged nonlinear modeling approaches were employed to examine the association between precipitation and GI-related hospital admissions. Results showed that the cumulative risk ratios (RRs) of GI-related hospital admissions were elevated in the 2 weeks following precipitation events; however, there were differences observed across study locations. The cumulative RR of GI-related hospitalizations was significantly higher when the amount of daily precipitation ranged from 3.3 mm to 13.5 mm in Dallas and from 6.0 mm to 24.5 mm in Houston. Yet, substantial increases in the cumulative RRs of GI-related hospitalizations were not observed in Austin or San Antonio. Age-specific and cause-specific GI-related hospitalizations were also found to be associated with precipitation events following the same pattern. Among them, Houston depicted the largest RR for overall GI and subgroup GI by age and cause, particularly for the overall GI among children aged 6 and under (RR = 1.35; 95 % CI = 1.11, 1.63), diarrhea-caused GI among children aged 6 and under (RR = 1.38, 95 % CI = 1.13, 1.69), and other-caused GI among children age 6 and under (RR = 1.46; 95 % CI = 1.12, 1.80). The findings underscore the need for public health interventions and adaptation strategies to address climate change-related health outcomes such as GI illness associated with extreme precipitation events.

Rainfall events and daily mortality across 645 global locations: two stage time series analysis

OBJECTIVE

To examine the associations between characteristics of daily rainfall (intensity, duration, and frequency) and all cause, cardiovascular, and respiratory mortality.

DESIGN

Two stage time series analysis.

SETTING

645 locations across 34 countries or regions.

POPULATION

Daily mortality data, comprising a total of 109 954 744 all cause, 31 164 161 cardiovascular, and 11 817 278 respiratory deaths from 1980 to 2020.

MAIN OUTCOME MEASURE

Association between daily mortality and rainfall events with return periods (the expected average time between occurrences of an extreme event of a certain magnitude) of one year, two years, and five years, with a 14 day lag period. A continuous relative intensity index was used to generate intensity-response curves to estimate mortality risks at a global scale.

RESULTS

During the study period, a total of 50 913 rainfall events with a one year return period, 8362 events with a two year return period, and 3301 events with a five year return period were identified. A day of extreme rainfall with a five year return period was significantly associated with increased daily all cause, cardiovascular, and respiratory mortality, with cumulative relative risks across 0-14 lag days of 1.08 (95% confidence interval 1.05 to 1.11), 1.05 (1.02 to 1.08), and 1.29 (1.19 to 1.39), respectively. Rainfall events with a two year return period were associated with respiratory mortality only, whereas no significant associations were found for events with a one year return period. Non-linear analysis revealed protective effects (relative risk <1) with moderate-heavy rainfall events, shifting to adverse effects (relative risk >1) with extreme intensities. Additionally, mortality risks from extreme rainfall events appeared to be modified by climate type, baseline variability in rainfall, and vegetation coverage, whereas the moderating effects of population density and income level were not significant. Locations with lower variability of baseline rainfall or scarce vegetation coverage showed higher risks.

CONCLUSION

Daily rainfall intensity is associated with varying health effects, with extreme events linked to an increasing relative risk for all cause, cardiovascular, and respiratory mortality. The observed associations varied with local climate and urban infrastructure.

Syndromic Surveillance in Public Health Emergencies: A Systematic Analysis of Cases Related to Exposure to 2023 Floodwaters in Romagna, Italy

BACKGROUND

In May 2023, Romagna, Italy, faced a devastating flood resulting in 16 fatalities, forced displacement of 26,000 citizens, and significant economic losses. Due to potential water contamination, implementing public health strategies became imperative for the Local Health Authority to mitigate the health consequences, analyze the flood's impact on the local population's health, and detect early anomalies requiring timely public health interventions.

METHODS

Between June and July 2023, general practitioners who were part of the RespiVirNet surveillance network completed weekly structured forms. These forms collected data on individuals exposed or not to floodwaters and clinical syndromes. Rates per 1000 resident population aged > 14 were stratified by district, week of observation, and symptomatology. Missing data were addressed by imputation using second-order autoregressive modeling.

RESULTS

An incidence of 3.52 syndromes potentially related to flood water exposure per 1000 individuals (95% CI 2.82-4.35) was estimated. Ravenna, the city most affected by the flood, recorded the highest rate (6.05 per 1000, 95% CI 4.59-7.82). Incidence decreased in the weeks post-event. Anxiety, or trauma and stress symptoms, exhibited higher rates among the exposed, diminishing over weeks. The incidence for the non-exposed (12.76 per 1000, 95% CI 10.55-15.29) showed no significant territorial differences compared to the exposed ones.

CONCLUSIONS

Syndromic surveillance provided timely information on the flood's health impact, revealing a higher incidence of individual syndromes among the non-exposed. This study contributes to guiding the implementation of future public health preparedness and response strategies for populations facing similar natural disasters.

Rainfall and Temperature Influences on Childhood Diarrhea and the Effect Modification Role of Water and Sanitation Conditions: A Systematic Review and Meta-Analysis

The latest report from the Intergovernmental Panel on Climate Change (IPCC) highlighted the worsening impacts of climate change. Two climate factors-temperature and rainfall uncertainties-influence the risk of childhood diarrhea, which remains a significant cause of morbidity and mortality in low- and middle-income countries. They create a conducive environment for diarrhea-causing pathogens and overwhelm environmental prevention measures. This study aimed to produce comprehensive evidence on the association of temperature and rainfall variability with the risk of childhood diarrhea and the influence of water and sanitation conditions on those associations. We conducted a systematic review and meta-analysis using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) approach. Records published in English from 2006 to 2023 were searched on 8 January 2024 via PubMed, EMBASE, ScienceDirect, Scopus, the Cochrane Library, and Google/Google Scholar using comprehensive search terms. We assessed studies for any risk of bias using the Navigation Guide and rated the quality of the evidence using the GRADE approach. The heterogeneity among estimates was assessed using I-squared statistics (I2). The findings of the analysis were presented with forest plots using an incidence rate ratio (IRR). A meta-analysis was conducted on effect modifiers (water supply and sanitation conditions) using a random effects model with a 95% confidence interval (CI). The statistical analyses were conducted using R 4.3.2 software and Review Manager 5.3. A total of 2017 records were identified through searches, and only the 36 articles that met the inclusion criteria were included. The analysis suggests a small positive association between increased temperature and the occurrence of under-five diarrhea, with the pooled IRR = 1.04; 95% CI [1.03, 1.05], at I2 = 56% and p-value < 0.01, and increased rainfall and U5 diarrhea, with IRR = 1.14; 95% CI [1.03, 1.27], at I2 = 86% and p-value < 0.01. The meta-analysis indicated a positive association between unimproved latrine facilities and drinking water sources with a rainfall-modified effect on U5 diarrhea, with IRR = 1.21; 95% CI [0.95, 1.53], at I2 = 62% and p-value = 0.03. We found that an increase in mean temperature and rainfall was associated with an increased risk of childhood diarrhea. Where there were unimproved latrine facilities and drinking water sources, the increase in mean rainfall or temperature would increase the incidence of childhood diarrhea. The results of this review help in assessing the effectiveness of current intervention programs, making changes as needed, or creating new initiatives to lower the prevalence of childhood diarrhea.

Health and climate change: adaptation policy in Aotearoa New Zealand

Recent extreme weather events attributable to climate change have major implications for policy. Here we summarize and evaluate the current state of climate change adaptation policy, from a health perspective, for Aotearoa New Zealand, based on government sources. Legislation relating to both environmental management and health are currently subject to major reforms. At present, adaptation policy emphasises protection of health care facilities from climate extremes; there is insufficient attention paid to broader determinants of health. We argue for greater health input into adaptation planning. Without intersectoral collaboration, contributions from diverse communities, and better support of indigenous solutions, climate change policy is unlikely to achieve effective health outcomes and there is a risk that climate change will exacerbate inequities. We recommend that the Climate Change Commission engage formally and directly with health bodies to strengthen the Commission's advice on the implications of climate change, and of national climate change policies, on health and equity. Climate resilient development does not occur without better public health. For this reason, the health sector has a critical role in the development and implementation of adaptation policy.

Mortality risks associated with floods in 761 communities worldwide: time series study

OBJECTIVE

To evaluate lag-response associations and effect modifications of exposure to floods with risks of all cause, cardiovascular, and respiratory mortality on a global scale.

DESIGN

Time series study.

SETTING

761 communities in 35 countries or territories with at least one flood event during the study period.

PARTICIPANTS

Multi-Country Multi-City Collaborative Research Network database, Australian Cause of Death Unit Record File, New Zealand Integrated Data Infrastructure, and the International Network for the Demographic Evaluation of Populations and their Health Network database.

MAIN OUTCOME MEASURES

The main outcome was daily counts of deaths. An estimation for the lag-response association between flood and daily mortality risk was modelled, and the relative risks over the lag period were cumulated to calculate overall effects. Attributable fractions of mortality due to floods were further calculated. A quasi-Poisson model with a distributed lag non-linear function was used to examine how daily death risk was associated with flooded days in each community, and then the community specific associations were pooled using random effects multivariate meta-analyses. Flooded days were defined as days from the start date to the end date of flood events.

RESULTS

A total of 47.6 million all cause deaths, 11.1 million cardiovascular deaths, and 4.9 million respiratory deaths were analysed. Over the 761 communities, mortality risks increased and persisted for up to 60 days (50 days for cardiovascular mortality) after a flooded day. The cumulative relative risks for all cause, cardiovascular, and respiratory mortality were 1.021 (95% confidence interval 1.006 to 1.036), 1.026 (1.005 to 1.047), and 1.049 (1.008 to 1.092), respectively. The associations varied across countries or territories and regions. The flood-mortality associations appeared to be modified by climate type and were stronger in low income countries and in populations with a low human development index or high proportion of older people. In communities impacted by flood, up to 0.10% of all cause deaths, 0.18% of cardiovascular deaths, and 0.41% of respiratory deaths were attributed to floods.

CONCLUSIONS

This study found that the risks of all cause, cardiovascular, and respiratory mortality increased for up to 60 days after exposure to flood and the associations could vary by local climate type, socioeconomic status, and older age.

Monsoon flood risks in urban areas of Pakistan: A way forward for risk reduction and adaptation planning

Climate change poses a significant threat to sustainable urban development. Heavy rainfall has led to severe urban flooding, disrupting human life and causing widespread damage. This study aims to examine the impacts, preparedness, and adaptation strategies related to monsoon flooding in Lahore, Pakistan's second-most populous metropolitan area. Using Yamane's sampling method, a total of 370 samples were surveyed and analyzed using descriptive analysis and chi-square tests. The results indicate that houses and parks were the most commonly damaged properties, with common impacts including roof collapse, house fires, seepage, and wall dampness. These impacts not only caused physical damage but also disrupted basic amenities and damaged roads, resulting in significant socioeconomic costs. Despite these challenges, residents adopted a variety of adaptation strategies such as the use of temporary tarps, moving household appliances to upper floors, and shifting to tiled floors and wall paneling to mitigate damage. However, the study highlights the need for further measures to reduce flood risks and promote adaptation planning in order to effectively address the ongoing challenges posed by climate change and urban flooding.

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.