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Systematic Review
Weather and infection
INTRODUCTION
Global climate change is expected to affect the frequency, intensity and duration of extreme water-related weather events such as excessive rainfall, storm surges, floods, and drought [1-3]. Recent extreme water-related weather events have included drought in Russia and flooding in Sri Lanka, the Philippines, Pakistan, Australia and Brazil. Weather is expected to become more extreme and variable due to acceleration of the water cycle caused by atmospheric heating. Altered pressure and temperature patterns, caused by global warming, may also shift the distribution of when and where extreme water-related events usually occur [4]..The frequency of heavy precipitation events is thought to have increased over many mid-latitude regions since 1950, even where there has been a reduction in the total precipitation. The area affected by drought is thought to have increased since the 1970s in many areas of the world [4]. There is also evidence to suggest that other extreme water-related weather events such as El Niño Southern Oscillation (ENSO), hurricanes, and cyclones are becoming more frequent, intense and of greater duration [4, 5].
Excessive or heavy rainfall events can mobilize pathogens in the environment and increase run-off of water from fields, transporting them into rivers, coastal waters and wells [1, 6]. Such events can therefore increase raw water turbidity, which has been found to be associated with gastrointestinal illness [7]. Heavy rainfall can also lead to changes in the direction of flow of water through channels that would not normally occur [8]. During periods of heavy rainfall, water treatment plants may be overwhelmed, there may be cross-contamination between sewage and drinking-water pipes (particularly where water infrastructure is old), sewage overflow, or bypass into local waterways [9]. Extreme precipitation events may also increase the risk of flooding in many areas, increasing human exposure to waterborne pathogens [10]. Droughts or extended dry periods are known to reduce the volume of river flow and potentially increase the concentration of effluent-derived pathogens, due to reduced dilution by stream-receiving waters [11].
Outbreaks caused by the contamination of community water systems have the potential to cause extensive disease [12], particularly where the public health infrastructure is less resilient. Waterborne diseases are expected to rise with increases in extreme...