Climate Change and the European Water Dimension - Agri ...

severe flooding were investigated (Wade et al., 2004) and an increase in the
incidence of gastrointestinal symptoms during the flood was observed with excess
among people with high susceptibility to infectious gastrointestinal illness. An
analysis of the relationship between precipitation and waterborne diseases, based on
the US EPA waterborne disease database (548 reports outbreaks from 1948-1994)
and precipitation data from the National Climatic Data Centre, showed that there was
a statistically significant association between the two with outbreaks due to surface
water contamination having the strongest association with extreme precipitation
during the month of the outbreak (Curriero et al., 2001). An example of a rather
severe outbreak is the E. coli O157:H7 outbreak following heavy rainfall and flooding
in Walkerton, Canada, which cost 6 lives and had 65 hospital admissions
(Anonymous, 2000). For developing countries outbreaks of leptospirosis, hepatits E,
malaria and diarroheal diseases following floods have also been described. Hunter
(2003) gives a concise review of the epidemiology of waterborne disease outbreaks
associated with climate change or extreme whether events by dividing the impact of
climate in three major groups: heavy rainfall events, flooding and increased
temperature. Even the increased flow rate of rivers will cause more resuspension of
pathogenic microorganisms accumulated in sediments, shorter residence times and
therefore less inactivation of pathogens. In case of ground waters, contamination
originates from manure on the land or from wastewater leaking from sewage pipes or
septic tanks. Due to increased water flow rates, transport of pathogens is faster
requiring larger protection zones. Moreover, increased urbanization continues to alter
watersheds and freshwater flows, resulting in contamination from both point sources
(factory and sewage treatment discharge plant) and non point sources (microbecontaminated
runoff from farmlands).
The role of water quality in outbreaks is often overlooked and underreported; some
waterborne diseases such as salmonellosis, campylobacteriosis and giardiasis may
cause only mild discomfort in healthy individuals. Many do not seek medical
attention, dismissing the symptoms as food poisoning or stomach flu. The link
between climate-mediated water contamination and outbreaks is easy to miss. A twomonth
lag is typical between heavy rainfall and the detection of groundwater
contamination. One month usually passes before dirtied water causes widespread
illness (Diaz, 1996). Quantifying the real threat of waterborne disease is thus difficult
due to the fact that many cases, typically gastroenteritis, go unreported: symptoms
usually do not last long and are self limiting in healthy people (Bernasconi, 2004).
However gastrointestinal illnesses can be chronic and even fatal in children, the
elderly, pregnant women and immuno-compromised people such as transplanted,
people affected by AIDS (acquired immune deficiency syndrome) or diabetes or
undergoing chemotherapy. Waterborne pathogens can even cause extended
illnesses, such as hepatitis, that last several months even in healthy people and they
are often associated with other serious conditions including hepatic, lymphatic,
neurologic, endocrinologic diseases (ASM, 1998) and even increased cancer risk
(e.g. Helicobater pylory and MALT lymphoma). Even more concern is due to the
emergence or re-emergence of new pathogens, antibiotic resistant strains and a
larger susceptible population (Gerba et al., 1996). For example, cclimate change can
influence the potential for Legionella, an emerging pathogen, to colonize water and
air conditioning systems (Rose et al., 2001), either directly due to increased
temperatures or indirectly (nutrients, association with free living amoebas, such as
Acanthamoeba).
Climate change may have effects on different environments and thus on associated
diseases: wetlands (encephalitis, malaria, schistosomiasis), permanent water
(filariasis, malaria, schistosomiasis, onchocerciasis), sea surface temperature, height
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