Food-borne diseases

Climate change and food-borne disease

Climate change is a significant threat to global food safety. Changes to temperature, humidity, rainfall patterns and the increasing frequency and intensity of extreme weather events are already affecting many aspects of the food system. Changes in weather and climatic patterns also affect the frequency and severity of some foodborne diseases, as well as the spread of pathogenic viruses, bacteria, and toxin-producing microorganisms. Climate changes influence also the spread of invasive alien species and vectors, which can be harmful to plant, animal, and human health. Surface seawater warming and ocean acidification, combined with increased nutrient inputs, can also lead to the growth and spread of toxin-producing algae. This puts the safety of seafood at risk and can cause outbreaks related to seafood consumption in coastal areas.

Mycotoxins

Mycotoxins are toxic compounds that are naturally produced by the Aspergillus, Penicillium, Fusarium and Claviceps fungi species. Climate change alters fungal behavior and distribution, leading to the spread of toxins in new locations. Temperature and humidity are important factors influencing fungal growth, crop infection, and mycotoxin toxicity. For example, aflatoxins are carcinogenic mycotoxins produced by two species of Aspergillus, a fungus found in areas with hot and humid climates (EFSA, 2020a). Rising temperatures and humidity linked to climate change likely contributed to the appearance of aflatoxins in Southern Europe in the early 2000s and their steady spread northwards since then. The emergence of aflatoxins in cereals in the EU due to climate change has been modelled, predicted and mapped in Battilani et al., 2012.

Only certain fungi species are responsible for the major classes of mycotoxins that are linked to health concerns. These mycotoxins include Aflatoxin B₁ (AFB₁), Deoxynivalenol (DON), Fumonisin B₁ (FB₁), Zearalenone (ZEN) and Ochratoxin A (OTA). These species can contaminate crops, food, and animal feed, leading to a range of negative health effects, including disruption to the endocrine and nervous system. They may also be carcinogenic (EEA, 2025).

Mycotoxins can be found in agricultural products all over the world. For example, DON, a trichothecene, is frequently found in wheat, maize and barley in temperate regions (EEA, 2025). FB₁ occurs mainly in maize, wheat and other cereals (Battilani et al., 2016; HBM4EU, 2022a; Khan, 2024). Both these toxins can cause health concerns. Different types of mycotoxins can also mix in crops, food, and feed, potentially interacting and increasing the risks for animals and humans (EFSA 2020b).

Mycotoxins can appear in plants during growth or after harvest and can remain in food even after washing, cooking or processing. This is because some are resistant to heat and typical food preparation methods. Detecting mycotoxins in food, feed, and crops is difficult without testing as they are often invisible and are also odorless and tasteless (EEA, 2025).

An overview of the health impacts associated with exposure to DON and FB₁ is presented below (Figure 1). This figure was produced for the EEA briefing on mycotoxins and is based on human biomonitoring data from the Horizon 2020 project HBM4EU which explored the health impacts associated with exposure to DON and FB₁ (EEA, 2025)_.

Figure 1 Overview of the health effects associated with exposure to DON and FB1 and possible exposure routes depending on the various exposure scenarios (EEA, 2025)

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).

Ciguatoxins and other marine biotoxins

Marine biotoxins are chemical contaminants naturally produced by certain types of algae and other microorganisms. They can enter the food chain mainly through the consumption of fish and other seafood such as mollusks and crustaceans. Temperature strongly influences their presence in marine and freshwater environments (EFSA, 2020c).

Ciguatera fish poisoning is the most common type of marine biotoxin food poisoning worldwide, with an estimated 20,000-50,000 cases per year. However, studies indicate that less than 10% of actual cases are ever reported (Canals et al. 2021). Ciguatera fish poisoning is typically caused by the consumption of fish that have accumulated ciguatoxins (CTX) in their flesh. CTX are produced by two families of microalgae called Gambierdiscus spp. and Fukuyoa spp. Consumers eating CTX contaminated fish can suffer from a range of short and long-term symptoms including gastrointestinal, cardiovascular and neurological effects.

Gambierdiscus and Fukuyoa are typical of tropical and subtropical areas. However, in 2004 Gambierdiscus was detected in water in Canary Island and Madeira. Gambierdiscus has also been found in several Mediterranean islands including Crete, Cyprus and the Balearics (Canals et al. 2021). Since 2008 a series of authochtonous outbreaks was recorded in Canary Islands, Spain and in Maderia, Portugal.

During 2023, marine biotoxins were responsible for 38 foodborne outbreaks in the EU, reported by France and Spain, seven more outbreaks than in 2022 (an increase of 22.6%). France accounted for most of these foodborne outbreaks (28 FBOs; 73.7%). Ciguatoxins were implicated in eight foodborne outbreaks while in the other foodborne outbreaks the specific marine biotoxins were not specified (EFSA & ECDC, 2024).

Response

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).