Editing IPCC:AR6/WGII/Chapter-7 (section)

==== 7.2.2.3 Observed Impacts on Food-Borne Diseases ====

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FBDs refer to any illness resulting from ingesting food that is spoiled or contaminated by pathogenic bacteria, viruses, parasites, toxins, pesticides and/or medicines ( [[#WHO--2018b|WHO, 2018b]] ). FBD risks are present throughout the food chain, from production to consumption, and most often arise due to contamination at source and from improper food handling, preparation and/or storage ( [[#Smith--2019|Smith and Fazil, 2019]] ; [[#Semenza--2021|Semenza and Paz, 2021]] ). As with WBDs, FBD outbreaks can follow multiple causal pathways as climatic risk factors interact with food production and distribution systems, urbanisation and population growth, resource and energy scarcity, decreasing agricultural productivity, price volatility, modification of diet trends, new technologies and the emergence of antimicrobial resistance ( [[#Lake--2018|Lake, 2018]] ; [[#Yeni--2017|Yeni and Alpas, 2017]] ). The burden of FBDs is also linked to malnutrition as reduced immunity increases susceptibility to various food-borne pathogens and toxins ( [[#FAO--2020|FAO, 2020]] ).

''A strong association exists between increases in FBDs and high air and water temperatures and longer summer seasons (very high confidence).'' The risks occur through complex transmission pathways throughout the food chain and the wide range of food-borne pathogens ( [[#Cisse--2019|Cisse, 2019]] ; [[#Hellberg--2016|Hellberg and Chu, 2016]] ; [[#Lake--2018|Lake and Barker, 2018]] ; [[#Park--2018b|Park et al., 2018b]] ; [[#Smith--2019|Smith and Fazil, 2019]] ). The food-borne pathogens of most concern are those having low infective doses, a significant persistence in the environment and high stress tolerance to temperature change (e.g., enteric viruses, ''Campylobacter'' spp., Shiga toxin-producing ''E. coli'' strains, ''Mycobacterium avium,'' tuberculosis complexes, parasitic protozoa and ''Salmonella'' ) ( [[#Lake--2018|Lake, 2018]] ; [[#Lake--2017|Lake, 2017]] ; [[#Lake--2018|Lake and Barker, 2018]] ; [[#Smith--2019|Smith and Fazil, 2019]] ; European Food Safety Authority 2020; [[#Semenza--2021|Semenza and Paz, 2021]] ). Priority risks include marine biotoxins, mycotoxins, salmonellosis, vibriosis, transfer of contaminants due to extreme precipitation, floods, increased use of chemicals in the food chain (plant protection products, fertilizers, veterinary drugs) and potential residues in food (European Food Safety Authority 2020; World Health Organization 2018b).

''There is a strong association observed between the increase in average ambient temperature and increases in'' Salmonella ''infections (high confidence).'' Most types of ''Salmonella'' infections lead to salmonellosis, while some other types ( ''Salmonella'' Typhi and ''Salmonella'' Paratyphi) can lead to typhoid fever or paratyphoid fever. The transmission to humans of the non-typhoidal ''Salmonella'' infection, one of the most widespread FBDs, usually occurs through eating foods contaminated with animal faeces. Studies conducted in Australia ( [[#Milazzo--2016|Milazzo et al., 2016]] ), New Zealand ( [[#Lal--2016|Lal et al., 2016]] ), the UK ( [[#Lake--2017|Lake, 2017]] ), South Korea ( [[#Park--2018a|Park et al., 2018a]] ; [[#Park--2018c|Park et al., 2018c]] ; [[#Park--2018a|Park et al., 2018a]] ), Singapore ( [[#Aik--2018|Aik et al., 2018]] ) and Hong Kong, SAR of China ( [[#Wang--2018a|Wang et al., 2018a]] ; [[#Wang--2018b|Wang et al., 2018b]] ), have shown that ''Salmonella'' outbreaks are strongly associated with temperature increases.

''Significant associations exist between FBDs due to'' Campylobacter '', precipitation and temperature (medium confidence).'' The timing of heat-associated Campylobacteriosis events varies across countries, with infection rates in the UK appearing to decline immediately after periods of high rainfall ( [[#Djennad--2019|Djennad et al., 2019]] ; [[#Lake--2019|Lake et al., 2019]] ; [[#Rosenberg--2018|Rosenberg et al., 2018]] ; [[#Yun--2016|Yun et al., 2016]] ; [[#Weisent--2014|Weisent et al., 2014]] ). This suggests the association with climate may be indirect and due to weather conditions that encourage outdoor food preparation and recreational activities ( [[#Lake--2017|Lake, 2017]] ; [[#Semenza--2021|Semenza and Paz, 2021]] ).

Outbreaks of human and animal ''Cryptococcus'' have been reported as being associated with a combination of climatic factors and shifts in host and vector populations ( [[#Chang--2015|Chang and]] [[#Chen--2015|Chen, 2015]] ; [[#Rickerts--2019|Rickerts, 2019]] ). The prevalence of childhood cryptosporidiosis, which is the second leading cause of moderate to severe diarrhoea among infants in the tropics and subtropics, shows associations with population density and rainfall, with contamination due to ''Cryptosporidium'' spp. being 2.61 times higher during and after heavy rain ( [[#Lal--2019|Lal et al., 2019]] ; [[#Young--2015|Young et al., 2015]] ; [[#Khalil--2018|Khalil et al., 2018]] ). Studies from Ghana, Guinea Bissau, Tanzania, Kenya and Zambia show a higher prevalence of ''Cryptosporidium'' during high rainfall seasons, with some peaks observed before, at the onset or at the end of the rainy season ( [[#Squire--2017|Squire and Ryan, 2017]] ).

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