8.2.4 Food safety
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). These studies found an approximately linear increase in reported cases with each degree increase in weekly or monthly temperature. 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 temperature-sensitive. Fly activity is largely driven by temperature rather than by biotic factors (Goulson et al., 2005). In temperate countries, warmer weather and milder winters are likely to increase the abundance of flies and other pest species during the summer months, with the pests appearing earlier in spring.
Harmful algal blooms (HABs) (see Chapter 1, Section 22.214.171.124) produce toxins that can cause human diseases, mainly via consumption of contaminated shellfish. Warmer seas may thus contribute to increased cases of human shellfish and reef-fish poisoning (ciguatera) and poleward expansions of these disease distributions (Kohler and Kohler, 1992; Lehane and Lewis, 2000; Hall et al., 2002; Hunter, 2003; Korenberg, 2004). For example, sea-surface temperatures influence the growth of Gambierdiscus spp., which is associated with reports of ciguatera in French Polynesia (Chateau-Degat et al., 2005). No further assessments of the impact of climate change on shellfish poisoning have been carried out since the TAR.
Vibrio parahaemolyticus and Vibrio vulnificus are responsible for non-viral infections related to shellfish consumption in the USA, Japan and South-East Asia (Wittmann and Flick, 1995; Tuyet et al., 2002). Abundance is dependent on the salinity and temperature of the coastal water. A large outbreak in 2004 due to the consumption of contaminated oysters (V. parahaemolyticus) was linked to atypically high temperatures in Alaskan coastal waters (McLaughlin et al., 2005).
Another example of the implications that climate change can have for food safety is the methylation of mercury and its subsequent uptake by fish and human beings, as observed in the Faroe Islands (Booth and Zeller, 2005; McMichael et al., 2006).