Quantifying the impact of climate change on enteric waterborne pathogen concentrations in surface water

https://doi.org/10.1016/j.cosust.2011.10.006Get rights and content

Climate change, among other factors, will impact waterborne pathogen concentrations in surface water worldwide, possibly increasing the risk of diseases caused by these pathogens. So far, the impacts are only determined qualitatively and thorough quantitative estimates of future pathogen concentrations have not yet been made. This review shows how changes in temperature and precipitation influence pathogen concentrations and gives opportunities to quantitatively explore the impact of climate change on pathogen concentrations using examples from ecological and hydrological modelling, already available statistical and process-based pathogen models and climate change scenarios. Such applications could indicate potential increased waterborne pathogen concentrations and guide further research.

Highlights

Climate change impacts on waterborne pathogen concentrations in surface water. ► These concentrations are expected to increase. ► Available ecological and hydrological scenario studies provide opportunities. ► Statistical and process-based models and climate scenarios help quantify the impacts.

Introduction

Diarrhoea caused by waterborne pathogens is a problem worldwide [1, 2]. In developed countries outbreaks are reported regularly [e.g. 3], but in developing countries the problems are larger due to poor sanitation and drinking water facilities. In low-income countries, diarrhoea is the 3rd leading cause of death [4]. Climate change  in addition to other factors, such as land-use change [5, 6, 7] (which are important, but not the focus of this review)  increases the risk of disease caused by waterborne pathogens [e.g. 8, 9, 10, 11, 12, 13]. Qualitatively, the impacts of climate change on disease caused by waterborne pathogens seem well established. For instance, many disease outbreaks have been connected to floods [e.g. 14] and the number of floods is expected to increase with climate change [15]. However, quantitative proof of these impacts is still problematic and many papers have called for further research on this topic [e.g. 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23•, 24, 25, 26, 27, 28] McMichael et al. [29] estimate that in 2000, 3% of the diarrhoea cases worldwide were caused by climate change but this number is very uncertain due to data limitations [30]. Their values are, however, consistent with a study by Kolstad and Johansson [31], who also acknowledge the apparent uncertainties. Other recent studies show a statistical relationship between diarrhoea and climate variables [e.g. 1, 14, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50], but many problems remain. A major problem is the availability of complete epidemiological data [2]. In developing countries surveillance and reporting systems may not have been in place for a long time, and patients with diarrhoea will not necessarily attend a doctor so their illness may go unreported. Moreover, there are many other complicating factors in epidemiological research. For example, confounding variables, such as additional transmission routes (for instance person-to-person contact) may confuse results. Another evident example is that seasonality of water source and latrine usage is often not accounted for in a comparison with seasonality of water quality. This may result in incorrect conclusions [51, 52].

Risk of disease is dependent on the pathogen concentration in water [53, 54]. The concentration of pathogens in the water is also expected to be impacted by climate change [55], similar to the risk of disease. Observations of waterborne pathogens may be problematic (e.g. difficulty with recovery rates of protozoa or incomplete cover of observations) [e.g. 56, 57], but for several pathogens and regions thorough observations are available. This review therefore focuses on pathogen concentrations in surface waters.

Quantification of the impact of climate change on the concentration of pathogens in surface water is also still in its infancy. To the author's knowledge, so far only one study quantitatively showed that a future increase in water temperatures will likely increase the inactivation rate of pathogens [58]. This indicates that the waterborne pathogen concentrations could decline with climate change. However, the consequences of changes in precipitation are ignored. There are many opportunities to quantitatively study the impacts of climate change on waterborne pathogen concentrations. The objective of this paper is to show these opportunities by reviewing the recent literature. The review first briefly discusses the impacts of climate change on concentrations of waterborne pathogens qualitatively. Then it assesses and discusses opportunities for quantitative approaches, focussing on statistical and process-based models and using experiences from other fields.

Section snippets

Conceptual model

Figure 1 conceptually describes the fate of waterborne pathogens in the environment and the impacts of climate change on concentrations of waterborne pathogens in the surface water. This figure summarises the different pathways that are described in the literature. The conceptual model shows two main pathways to the environment: point sources from humans through waste water treatment plants (that may have differing efficiencies in removing pathogens), and diffuse sources from humans and animal

Statistical modelling

Many studies have shown a relationship between precipitation, runoff or discharge and the concentration of faecal indicator organisms or waterborne pathogens in surface water [e.g. 51, 64, 73, 74, 75, 76, 77, 78, 79, 80, 81] and several have proven this relationship to be statistically significant [e.g. 54, 82, 83, 84, 85, 86, 87, 88, 89, 90]. Most of these studies focus on precipitation but some have also considered water temperature. Positive correlations have been observed between water

Process-based modelling

Another way to estimate waterborne pathogen concentrations is process-based modelling. Several waterborne pathogen models simulate this at catchment [101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111] and country [112] level. The models generally include the processes shown in black in Figure 1. The available models still have many limitations. Oliver et al. [113], Pachepsky et al. [114] and Jamieson et al. [115] review the models and their limitations, which include, for example, lack of

General discussion points

The models that are suitable for use in climate impact studies exist only for catchments in developed countries (mainly Australia, United States and Europe). This is problematic. As described in the introduction, the problems with diarrheal disease are largest in developing countries [7]. However, these areas are data sparse and no modelling experiments have been done there. Modelling waterborne pathogens in the developing countries and the impact of climate change on these pathogens there is a

Conclusion

This paper has given a review of the literature for opportunities to quantify the impact of future climate change on pathogen concentrations in surface waters. This topic is important, because every year still nearly two million children die due to diarrhoeal diseases [145, 146] and many more children and adults are affected. This number could well increase due to climate change. Examples from ecological and hydrological modelling of shifting species and changed water flows show that

References and recommended reading

Papers of particular interest, published within the period of review, have been highlighted as:

  • • of special interest

References (146)

  • J.T. Freeman et al.

    Seasonal peaks in Escherichia coli infections: possible explanations and implications

    Clin Microbiol Infect

    (2009)
  • I. Delpla et al.

    Impacts of climate change on surface water quality in relation to drinking water production

    Environ Int

    (2009)
  • F.M. Schets et al.

    Cryptosporidium and Giardia in swimming pools in the Netherlands

    J Water Health

    (2004)
  • R.L. Wilby et al.

    Climate change impacts and adaptation: a science agenda for the Environment Agency of England and Wales

    Weather

    (2005)
  • J. Wu et al.

    Fate and transport modeling of potential pathogens: the contribution from sediments

    J Am Water Resour Assoc

    (2009)
  • H.A.J. Senhorst et al.

    Climate change and effects on water quality: a first impression

    Water Sci Technol

    (2005)
  • H.Y. Richardson et al.

    Microbiological surveillance of private water supplies in England  the impact of environmental and climate factors on water quality

    Water Res

    (2009)
  • R.C. Wright

    The seasonality of bacterial quality of water in a tropical developing country (Sierra Leone)

    J Hyg

    (1986)
  • R. Feachem

    Faecal coliforms and faecal streptococci in streams in the new guinea highlands

    Water Res

    (1974)
  • K.E. Schilling et al.

    Temporal variations of Escherichia coli concentrations in a large Midwestern river

    J Hydrol

    (2009)
  • J. Méndez et al.

    Assessment of drinking water quality using indicator bacteria and bacteriophages

    J Water Health

    (2004)
  • C.M. Ferguson et al.

    Relationships between indicators, pathogens and water quality in an estuarine system

    Water Res

    (1996)
  • D. Kay et al.

    Predicting coliform concentrations in upland impoundments: design and calibration of a multivariate model

    Appl Environ Microbiol

    (1983)
  • M.B. Nevers et al.

    Nowcast modeling of Escherichia coli concentrations at multiple urban beaches of southern Lake Michigan

    Water Res

    (2005)
  • T.P. Dawson et al.

    Beyond predictions: biodiversity conservation in a changing climate

    Science

    (2011)
  • P. Karanis et al.

    Waterborne transmission of protozoan parasites: a worldwide review of outbreaks and lessons learnt

    J Water Health

    (2007)
  • W.R. Mac Kenzie et al.

    A massive outbreak in Milwaukee of Cryptosporidium infection transmitted through the public water-supply

    N Engl J Med

    (1994)
  • WHO

    The Global Burden of Disease: 2004 Update

    (2008)
  • K.D. Lafferty

    The ecology of climate change and infectious diseases

    Ecology

    (2009)
  • R.S. Ostfeld

    Climate change and the distribution and intensity of infectious diseases

    Ecology

    (2009)
  • I. Kurane

    The emerging and forecasted effect of climate change on human health

    J Health Sci

    (2009)
  • P.R. Hunter

    Climate change and waterborne and vector-borne disease

    J Appl Microbiol

    (2003)
  • A.B.A. Boxall et al.

    Impacts of climate change on indirect human exposure to pathogens and chemicals from agriculture

    Environ Health Perspect

    (2009)
  • E. Fearnley et al.

    Climate change, societal transitions and changing infectious disease burdens

    Changing Climates, Earth Systems and Society

    (2010)
  • K. Koelle et al.

    Refractory periods and climate forcing in cholera dynamics

    Nature

    (2005)
  • M. Ahern et al.

    Global health impacts of floods: epidemiologic evidence

    Epidemiol Rev

    (2005)
  • G. Nichols et al.

    Rainfall and outbreaks of drinking water related disease and in England and Wales

    J Water Health

    (2009)
  • G.A. Meehl et al.

    Global climate projections

  • D. Campbell-Lendrum et al.

    Comparative risk assessment of the burden of disease from climate change

    Environ Health Perspect

    (2006)
  • Confalonieri U, McMichael A: Global Environmental Change and Human Health. Science Plan and Implementation Strategy....
  • U. Confalonieri et al.

    Human health

  • J.A. Patz et al.

    Health impact assessment of global climate change: expanding on comparative risk assessment approaches for policy making

    Ann Rev Public Health

    (2008)
  • J.B. Rose et al.

    Climate variability and change in the United States: potential impacts on water- and foodborne diseases caused by microbiological agents

    Environ Health Perspect

    (2001)
  • J.C. Semenza et al.

    Climate change and infectious diseases in Europe

    Lancet Infect Dis

    (2009)
  • T.E. Ford et al.

    Using satellite images of environmental changes to predict infectious disease outbreaks

    Emerg Infect Dis

    (2009)
  • D. Campbell-Lendrum et al.

    Health and climate change: a roadmap for applied research

    Lancet

    (2009)
  • A. McMichael et al.

    Global climate change

  • K.L. Ebi

    Healthy people 2100: modeling population health impacts of climate change

    Climatic Change

    (2008)
  • E.W. Kolstad et al.

    Uncertainties associated with quantifying climate change impacts on human health: a case study for diarrhea

    Environ Health Perspect

    (2011)
  • F.C. Curriero et al.

    The association between extreme precipitation and waterborne disease outbreaks in the United States, 1948–1994

    Am J Public Health

    (2001)
  • Cited by (111)

    • The impact of heavy precipitation and its impact modifiers on shigellosis occurrence during typhoon season in Taiwan: A case-crossover design

      2022, Science of the Total Environment
      Citation Excerpt :

      As we know, heavy precipitation may facilitate the contamination of water source through increasing surface runoff, resuspension/water turbidity, the chance of sewer overflow and so on. ( Hofstra, 2011; Levy et al., 2016). Previous studies revealed that heavy precipitation significantly increase concentrations of human-associated bacteria (e.g. Escherichia coli) in rivers during event period or few days after events (Olds et al., 2018; Tornevi et al., 2014).

    • A review on present and future microbial surface water quality worldwide

      2021, Environmental Nanotechnology, Monitoring and Management
      Citation Excerpt :

      The concentration of pathogens in surface water probably increases after extreme precipitation events due to increased surface runoff, sewer overflow and re-suspension from sediments (Funari et al., 2012; Hofstra, 2011). Simultaneously, increased precipitation decreases the concentration in surface water due to dilution (Hofstra, 2011). Increased temperatures can also facilitate inactivation rate of pathogens (An et al., 2002).

    • Modelling rotavirus concentrations in rivers: Assessing Uganda's present and future microbial water quality

      2021, Water Research
      Citation Excerpt :

      However, such studies mostly use historical diarrhoeal disease patterns. An integrated modelling approach combining socio-economic development and climate change impacts could provide new knowledge on future microbial water quality and the resulting diarrhoeal disease burden (Hofstra, 2011; Hofstra et al., 2019). Thus far, such studies are grossly limited.

    View all citing articles on Scopus
    View full text