a Systematic Review of Relationships between ... - ACS Publications

Apr 8, 2016 - availability.2 The Intergovernmental Panel on Climate Change. (IPCC) predicts that ... diarrhea, pathogen-specific diarrhea, gastroenter...
1 downloads 0 Views 4MB Size
Subscriber access provided by The University of British Columbia Library

Critical Review

Untangling the impacts of climate change on waterborne diseases: A systematic review of relationships between diarrheal diseases and temperature, rainfall, flooding, and drought Karen Levy, Andrew P Woster, Rebecca S Goldstein, and Elizabeth J Carlton Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.5b06186 • Publication Date (Web): 08 Apr 2016 Downloaded from http://pubs.acs.org on April 13, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 51

Environmental Science & Technology

1

Untangling the impacts of climate change on waterborne diseases: A systematic review of

2

relationships between diarrheal diseases and temperature, rainfall, flooding, and drought

3

Karen Levy* 1, Andrew P. Woster2, Rebecca S. Goldstein1, Elizabeth J. Carlton2

4 5

1

6

Atlanta, Georgia, USA

7

2

8

University of Colorado, Aurora, Colorado, USA

Department of Environmental Health, Rollins School of Public Health, Emory University,

Department of Environmental and Occupational Health, Colorado School of Public Health,

9 10

*

11

University Rollins School of Public Health, 1518 Clifton Road NE, Atlanta, GA 30322.

12

Telephone: 404.727.4502. Fax: 404.727.8744. E-mail: [email protected]

Address correspondence to: Karen Levy, Department of Environmental Health, Emory

13

14

15

1

ACS Paragon Plus Environment

Environmental Science & Technology

16

ABSTRACT

17

Global climate change is expected to affect waterborne enteric diseases, yet to date there has been

18

no comprehensive, systematic review of the epidemiological literature examining the relationship

19

between meteorological conditions and diarrheal diseases. We searched PubMed, Embase, Web

20

of Science and the Cochrane Collection for studies describing the relationship between diarrheal

21

diseases and four meteorological conditions that are expected to increase with climate change:

22

ambient temperature, heavy rainfall, drought, and flooding. We synthesized key areas of

23

agreement and evaluated the biological plausibility of these findings, drawing from a diverse,

24

multidisciplinary evidence base. We identified 141 articles that met our inclusion criteria. Key

25

areas of agreement include a positive association between ambient temperature and diarrheal

26

diseases, with the exception of viral diarrhea; and an increase in diarrheal disease following

27

heavy rainfall and flooding events. Insufficient evidence was available to evaluate the effects of

28

drought on diarrhea. There is evidence to support the biological plausibility of these associations,

29

but publication bias is an ongoing concern. Future research evaluating whether interventions,

30

such as improved water and/or sanitation access, modify risk would further our understanding of

31

the potential impacts of climate change on diarrheal diseases and aid in the prioritization of

32

adaptation measures.

33

34

KEYWORDS

35

Climate, Weather, Diarrhea, Climate Change, Ambient Temperature, Heavy Rainfall, Flooding,

36

Drought, Social Vulnerability

2

ACS Paragon Plus Environment

Page 2 of 51

Page 3 of 51

Environmental Science & Technology

37

INTRODUCTION

38

Global climate change has the potential to severely impact human health worldwide, including

39

diarrheal diseases,1 which are highly affected by environmental drivers such as water

40

availability.2 The Intergovernmental Panel on Climate Change (IPCC) predicts that global

41

surface temperature change for the end of the 21st century is likely to exceed 1.5°C relative to the

42

period from 1850-1900, and in some scenarios is likely to exceed 2°C. Changes in the global

43

water cycle also are expected, with increasing contrast in precipitation between wet and dry

44

regions and between wet and dry seasons, although there may be regional exceptions.3

45

Because of the projected impacts of climate change on hydrological systems, waterborne enteric

46

diseases are among the primary expected health impacts of climatic shifts.1, 4, 5 Understanding the

47

impact of meteorological phenomena on enteric diseases is critical because even relatively small

48

proportional increases in risk for diarrhea represent substantial overall impacts to the global

49

burden of disease. Diarrheal diseases account for 10-12% of all deaths in children under five

50

years old,6, 7 and an estimated 1.4-1.9 million deaths worldwide.7, 8 In addition to mortality,

51

diarrheal disease can impair growth and cognitive development, and increase susceptibility to

52

other infectious and chronic diseases,9 which may also exacerbate individual and community

53

vulnerability to climate change.

54

Despite the importance of this topic, to date there has been no comprehensive, systematic review

55

of the literature examining the relationship between climatic variables and patterns of diarrheal

56

diseases. Other authors have reviewed associations between temperature and all-cause

57

diarrhea,10, 11 meteorological variables and specific diarrheal pathogens,e.g., 12, 13-16 extreme

58

weather events and waterborne diseases,17 and climatic influences on pathogens in the

59

environment.18 However, these have been non-systematic reviews, focused on only one

3

ACS Paragon Plus Environment

Environmental Science & Technology

60

pathogen, and/or focused on specific geographical regions only. Thus, there is a need to review

61

and synthesize the body of data that has accumulated on this topic, using rigorous methods

62

following established guidelines,19-21 to better understand and interpret the epidemiological

63

patterns reported in the literature, inform climate change adaptation and mitigation measures, and

64

direct future research on the topic.

65

In this paper, we present the results of a systematic review of epidemiological associations

66

between diarrhea and ambient temperature, heavy rainfall, flooding, and drought. We chose

67

these meteorological conditions because of the strong evidence that these conditions are

68

increasing due to climate change, and because of prior publications suggesting associations with

69

diarrheal diseases. We summarize key areas of agreement, as well as gaps in the literature. In a

70

related paper we carried out a meta-analysis of the subset of these studies specifically related to

71

ambient temperature and diarrhea.22 Here we also evaluate the biological plausibility of each key

72

finding, presenting a conceptual framework that describes mechanisms to explain the observed

73

exposure-response relationships. We conclude by providing examples of how the insights from

74

this conceptual framework can be applied, including in the evaluation of adaptation strategies.

75 76 77

METHODS

78

Systematic Search

79

Articles were identified through a comprehensive search of the literature and by reviewing

80

references from 54 review articles identified through the search process. Briefly, we searched

81

PubMed, Embase, Web of Science, and The Cochrane Collection on 26 November 2013 for the

82

health outcome terms “diarrhea*” or “diarrhoea*”, paired with climate or meteorological terms:

4

ACS Paragon Plus Environment

Page 4 of 51

Page 5 of 51

Environmental Science & Technology

83

“climate change”, “temperature”, “rain*”, “precipitation”, “flood*”, “drought*,” and "sea surface

84

temperature".

85

Two independent reviewers considered all articles for inclusion. Articles were deemed to meet

86

inclusion criteria if they included: 1) human health outcome data; 2) all-cause diarrhea, pathogen-

87

specific diarrhea, gastroenteritis, or diarrhea and vomiting as outcomes; and 3) temperature,

88

heavy rainfall, flooding, or drought as exposures of interest related to rates of diarrheal diseases.

89

Only English-language articles were included. Case reports were excluded. Meta-analyses and

90

reviews were included if they provided a novel analysis of the data from the studies included.

91

We decided a priori to focus on articles evaluating heavy rainfall rather than average rainfall

92

because of previous work suggesting that this is the primary rainfall exposure influencing rates of

93

diarrheal diseases.23-25 While our search originally included sea surface temperature, we decided

94

to exclude this category because all 16 articles identified focused on cholera, limiting the

95

generalizability of such findings to other diarrheal diseases. Duplicate reports were handled by

96

selecting the study with the most complete dataset and analysis. Following initial article review,

97

the two reviewers discussed and resolved differences in inclusion decisions, consulting with the

98

other study authors as necessary. Figure 1 shows the PRISMA diagram19 of the selection process.

99

For each article that met our inclusion criteria, one reviewer extracted relevant data (including

100

exposure, outcome, location of study, study duration, study population) and at least one other

101

person verified the extracted information.

102

5

ACS Paragon Plus Environment

Environmental Science & Technology

103

Evaluating the quality of the evidence

104

We used three approaches to assess the quality of the evidence: 1) evaluating the weight of

105

evidence, including study design and strength and consistency of observed relationships; 2)

106

evaluating risk of bias; and 3) exploring biological plausibility of the relationships.

107

Weight of Evidence. Studies were classified as quantitative epidemiological studies, non-

108

quantitative epidemiological studies or outbreak reports. A study was classified as quantitative if

109

the authors presented the results of a statistical analysis. To account for potential publication bias,

110

we did not require studies to present actual point estimates, allowing us to include studies that

111

reported whether or not significant associations were detected by the particular analytical method

112

applied. When studies presented the results of multiple analyses, we followed the Cochrane

113

guidelines20 and selected the analysis that the authors indicated as the final or main analysis

114

(typically a fully adjusted model), and did not include supplementary exploratory studies.

115

However, when analyses were stratified by exposure, location, or another risk factor, and a single

116

unified estimate was not presented, we included each of the stratified analyses in our summary.

117

We limited temperature studies to those that examined associations between temperature and

118

diarrheal diseases at a one-month or finer resolution.

119

Quantitative studies were classified as showing positive or negative associations if the analysis

120

allowed rejection of the null hypothesis (p