Water and food-borne diseases (CLIM 038) - Assessment published Sep 2008
Climate change (Primary topic)
Typology: Descriptive indicator (Type A – What is happening to the environment and to humans?)
- CLIM 038
Key policy question: .
- There has been a linear increase in reported cases of some food-borne diseases for each degree increase in weekly or monthly temperature over a certain location-specific threshold (medium confidence). Several thousand cases of salmonella are expected in future years, particularly in countries where food safety standards are poor.
- Changing frequency and intensity of precipitation events (and temperature) from climate change may result in outbreaks of water-borne diseases (high confidence) and could mobilise pathogens.
- In the Mediterranean additional salmonella problems from bathing water quality are projected, which would require proper monitoring and surveillance.
Percentage change of weekly salmonella cases by 1 oC temperature increase
Note: The figure shows the percentage change of weekly salmonella cases 1 degree Celcius temperature increase
Kovats, R. S.; Edwards, S.; Hajat, S. et al., 2004. The effect of temperature on food poisoning: time series analysis in 10 European countries. Epidemiology and Infection 132 (3): 443.
Access to public sources of drinking water in EU Member States is high. Heavy precipitation has been linked to a number of drinking-water outbreaks of Cryptosporidium (a pathogen causing a diarrhoeal illness) in Europe, due to spores infiltrating drinking water reservoirs from springs and lakes and persisting in the water distribution system (Lake et al., 2005; Semenza and Nichols, 2007). In Germany, bacteriological and parasitic parameters spiked considerably during extreme runoff events (Kistemann et al., 2002). New pathogens have also emerged in recent years. In Europe the risk of infectious disease outbreaks is relatively small due to the standard of water treatment and distribution infrastructure. While water-borne outbreaks have a rather large potential, the actual disease burden in Europe is difficult to estimate and is most probably underestimated. Examples of an increased risk of infectious disease outbreaks have been found in the United Kingdom (Reacher et al., 2004), Finland (Miettinen et al., 2001), Czech Republic (Kriz et al., 1998) and Sweden (Lindgren, 2006).
Key food- and water-borne infections in Europe are monitored. The incidence of salmonella has been declining in many countries, but that of other pathogens is increasing. Several studies have confirmed and quantified the effects of high temperatures on common forms of food poisoning, such as salmonellosis (D'Souza et al., 2004; Kovats et al., 2004; Fleury et al., 2006) (see Figure 1). These found an approximately linear increase in reported cases with each degree increase in weekly or monthly temperature over a certain threshold. Temperature is much less important for the transmission of Campylobacter (Kovats et al., 2005; Louis et al., 2005; Tam et al., 2006). Contact between food and pest species, especially flies, rodents and cockroaches, is also temperaturesensitive. Fly activity is largely driven by temperature rather than by biotic factors (Goulson et al., 2005).
Harmful algal blooms (HABs) produce toxins that can cause human diseases, mainly via consumption of contaminated shellfish. Warmer seas may thus contribute to more cases of human shellfish and reef-fish poisoning (ciguatera) and poleward expansions of these disease distributions (Lehane and Lewis, 2000; Hall et al., 2002; Hunter, 2003; Korenberg, 2004).
Infections with Salmonella spp. increase by 5-10 % for each degree increase in weekly temperature, at ambient temperatures above 5 oC (Kovats et al., 2004). Some emerging studies show that the disease burden in Europe could be significant (all else being constant) with potentially an extra 20 000 cases per year by 2030 and 25 000-40 000 by 2080 (EC, 2007).
Water stress over central and southern Europe is projected to increase. In the EU, the percentage of land area under high water stress is likely to increase from 19 % today to 35 % by the 2070s, by when the number of additional people affected is expected to be between 16 and 44 million. Furthermore, in southern Europe and some parts of central and eastern Europe, summer water flows may be reduced by up to 80 %. By 2025 it is projected that an additional 31 million people will be living in the coastal zone of the Mediterranean, and that 130 million more will visit the region each year.
Effect of temperature on food poisoning
provided by London School of Hygiene and Tropical Medicine
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