Extreme water-related weather events and waterborne disease

Abstract

Global climate change is expected to affect the frequency, intensity and duration of extreme water-related weather events such as excessive precipitation, floods, and drought. We conducted a systematic review to examine waterborne outbreaks following such events and explored their distribution between the different types of extreme water-related weather events. Four medical and meteorological databases (Medline, Embase, GeoRef, PubMed) and a global electronic reporting system (ProMED) were searched, from 1910 to 2010. Eighty-seven waterborne outbreaks involving extreme water-related weather events were identified and included, alongside 235 ProMED reports. Heavy rainfall and flooding were the most common events preceding outbreaks associated with extreme weather and were reported in 55·2% and 52·9% of accounts, respectively. The most common pathogens reported in these outbreaks were Vibrio spp. (21·6%) and Leptospira spp. (12·7%). Outbreaks following extreme water-related weather events were often the result of contamination of the drinking-water supply (53·7%). Differences in reporting of outbreaks were seen between the scientific literature and ProMED. Extreme water-related weather events represent a risk to public health in both developed and developing countries, but impact will be disproportionate and likely to compound existing health disparities.

Fig. 1.

Algorithm used by reviewers when screening abstracts and grey literature to determine if inclusion criteria were met. * A list of examples of extreme water-related events to be included was provided. † A list of examples of waterborne pathogens to be included was provided

Fig. 2.

Flow chart detailing the passage of scientific and grey literature through the systematic review process.

Fig. 3.

Accounts of extreme weather events and waterborne disease outbreaks identified from the scientific literature and ProMED, by event type. Where more than one extreme event was reported, the account was included in each type of event.

Fig. 4.

Mean numbers of cases reported in accounts of waterborne disease outbreaks where extreme weather events have been implicated, by pathogen and case definition type (scientific literature): (a) using a laboratory-confirmed diagnosis, (b) using a self-reported diagnosis, (c) using a clinical diagnosis, (d) where type of diagnosis is not reported. Figures in parentheses indicate number of accounts reporting this information.

Fig. 5.

Mean numbers of cases reported in accounts of waterborne disease outbreaks where extreme weather events have been implicated, by event and case definition type (scientific literature): (a) using a laboratory-confirmed diagnosis, (b) using a self-reported diagnosis, (c) using a clinical diagnosis, (d) where type of diagnosis is not reported. Figures in parentheses indicate number of accounts reporting this information.