Food-borne diseases

Observed effects

Invasive and alien species and disease-carrying vectors

Alien species are animals, plants, or micro-organisms that have been introduced as a result of human activity (i.e. globalization of trade, growth of tourism) to an area it could not have reached on its own. If they become invasive, they can create serious problems in new territories, as for example, pests in agriculture or as vectors for diseases in animal husbandry. Climate change may affect the likelihood of alien species establishing in new locations by creating more favorable habitat conditions, leading to increased spread and a higher risk of infestation (EFSA, 2020c). For example, in Europe, apple snails pose a threat to southern European wetlands, with extreme weather events and flooding (influenced by climate change) increasing the natural spread of this pest via rivers and canals (EFSA, 2014).

Climate change may also play a role in the establishment and persistence of vector species (e.g. flies, mosquitos, ticks). A vector species is an animal that can transmit an infectious agent from an infected animal to a human or another animal. Information on the European distribution of several mosquitoes, ticks, sandfly and biting midges species, which can be vectors of pathogens affecting human or animal health, can be found in the VectorNet database.

Zoonotic diseases

The transmission of infections or diseases between animals and humans (“zoonotic diseases”) is a major source of food safety risk. Environmental factors such as temperature, rainfall and humidity influence the distribution and survival of bacteria such as Salmonella and Campylobacter. The presence of Norovirus in, for example, oysters, is also linked to sewage runoff caused by heavy rainstorm and flooding (EFSA, 2020c). Among issues for food safety with the highest likelihood of emergence in Europe, identified in EFSA (2020c), vibrio and ciguatoxins are most likely and both are related to the consumption of seafood.

As part of the effort to combat the health impacts of climate change, the joint annual EFSA-ECDC One Health Zoonoses reports tracks animal, food and human data jointly, enabling climate signals to surface (EFSA and ECDC, 2024).

Vibrio bacteria in seafood

Vibrios are waterborne bacteria that mainly live in coastal and brackish waters as they thrive in temperate and warm waters with moderate salinity. They can cause gastroenteritis or severe infections for people who have consumed raw or undercooked seafood/shellfish, such as oysters. Contact with water containing Vibrios can also cause wound and ear infections.

Due to an increase in extreme weather events, like heatwaves, over the past 20 years, Europe has seen a rise in Vibrio infections. Warmer coastal waters have led to an expansion of areas where Vibrio bacteria can multiply, resulting in a higher risk of infections from the consumption of contaminated seafood. Regions that are particularly at risk include those with brackish or low-salinity waters (e.g., the Baltic Sea, Baltic and North Sea transitional waters, and the Black Sea) as well as coastal areas with large-river inflows. A comprehensive overview of public health aspects of Vibrio spp. related to the consumption of seafood in the EU has recently been provided in EFSA (2024).

Policy responses

EFSA’s CLEFSA Project: Climate Change and Emerging Risks

From 2018 to 2020, EFSA conducted the CLEFSA project—“Climate change as a driver of emerging risks for food and feed safety, plant and animal health, and nutritional quality.” This initiative built upon EFSA’s prior work in climate-related risk assessments and leveraged its strong collaborations with national authorities, international organizations, the scientific community, and other stakeholders concerned with emerging risks and their drivers.

CLEFSA aimed to develop methods and tools to identify and characterize emerging risks linked to climate change. The project focused on:

• Identification of long-term risks using climate change scenarios;
• Horizon scanning and crowdsourcing to gather early warning signals from diverse
• Expanding the expert network to include specialists from EU and UN agencies;
• Designing tools based on multi-criteria decision analysis (MCDA) to assess risks in food and feed safety, plant and animal health, and nutritional quality.

The CLEFSA network brought together experts from international, EU, and UN bodies, as well as coordinators of major EU-funded climate change projects. This expert group played a central role in identifying emerging issues and shaping the MCDA tool. EFSA also adapted its existing emerging risk identification criteria to address the specific challenges posed by climate change.

The CLEFSA project has identified, characterized and statistically analyzed over 100 emerging issues/risks for food and feed safety, plant, animal health and nutritional quality, driven by climate change.

Climate change is likely to increase the severity, duration and/or frequency of the potential effects of new or re-emerging hazards and increase their likelihood of emergence. Marine biotoxins have been identified among those with the higher likelihood of emergence.

The results of the CLEFSA project were published in a comprehensive report in 2020 (EFSA, 2020).