As a result of increased frequency and intensity of heat waves, increased floods and droughts, change in climate will affect biological, physical, and chemical components of water through different paths thus enhancing the risk of waterborne diseases. Identifying the role of weather in waterborne infection is a priority public health research issue as climate change is predicted to increase the frequency of extreme precipitation and temperature events. This chapter provides evidence that precipitation and temperature can affect directly or indirectly water quality and consequently affect the health human. This chapter also highlights the complex relationship between precipitation or temperature and transmission of waterborne disease such as diarrheal disease, gastroenteritis, cryptosporidiosis, giardiasis, and cholera.
TopIntroduction
It has been known for thousands of years, that climate has wide ranging impacts on human health. In recent years there has been growing concern about the possible effects of climatic changes including their effect on health (Gosling et al. 2009). Climate change is expected to affect health by several mechanisms, (1) directly, as for instance drowning or trauma in extreme weather events, or (2) indirectly, by environmental degradation, scarcity of resources,, high rates of infectious disease, weak infrastructure, and overpopulation (Patz et al. 2005),increasing the exposure of human populations to risk factors (Funari et al. 2012). Vulnerable populations include the elderly, children, urban populations, and the poor (Ebi & Paulson 2010). 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 (Semenza & Menne 2009). Changes in the global water cycle also are expected, with increasing contrast in precipitation between wet and dry regions and between wet and dry seasons(Levy et al. 2016).
Altered pressure and temperature patterns, caused by global warming, may also shift the distribution of when and where extreme water-related events usually occur (Cann et al. 2013). A considerable amount of research is being conducted to map and assess risks, vulnerabilities and the impact of climate change in waterborne disease (Semenza et al. 2012). Some work like, Cann et al. (2013) have identified waterborne outbreaks potentially linked to an extreme water-related weather event and assessed the different types of extreme weather events impact the occurrence of waterborne disease. The impact of climate change on increasing of total and dissolved chemical and organic products as pesticides, heavy metals and hydrocarbons, and among the consequences on water quality is an increase pathogens (Hunter 2003; van Vliet & Zwolsman 2008). Heat waves also promotes harmful cyanobacteria blooms (Jöhnk et al. 2008). Water quality degradation is controlled by many factors (1) chemical (2) physical (3) biological and also socioeconomic factors (Figure 1). Most of these factors are often correlated with extreme meteorological events like heavy rainstorms or droughts. Short-term peaks in pathogen concentration including bacteria, virus and parasitic protozoa may increase disease risks considerably, and may result in outbreaks of waterborne diseases when associated with insufficient treatment at the water treatment works (WHO 2004).
Figure 1. Different factors impacting water quality
The purpose of this chapter was to analyze the relationship between waterborne diseases (such as diarrheal disease, gastroenteritis, cryptosporidiosis, giardiasis and cholera) and environmental factors such as temperature, heavy rainfall, flooding, and drought. We chose these meteorological conditions because of the strong evidence that these factors are increasing due to climate change, and because of prior publications suggesting associations with waterborne diseases. Rainfall intensity and temperature are assumed to be a key determining factor in the fate and transport of pathogenic microorganisms.
TopThe Impact Of Climate Change On Human Health
Climatic factors have an impact on water (surface water, rivers, and oceans), but temperature and precipitations are the key factors that control water parameters (like light, turbidity, heat, dissolved oxygen...). A short-term or long-term change in one or both of these factors can affect water quality, so we study the effect of climate change on water quality, to get closer to the direct or indirect impact of temperature and precipitation on human health via waters.