Climatic factors influence the growth and survival of pathogens, as well as transmission pathways. Higher ambient temperatures increase replication cycles of food-borne pathogens, and prolonged seasons may augment the opportunity for food handling mistakes - in 32% of investigated food-borne outbreaks in Europe “temperature misuse” is considered a contributing factor.
Campylobacter is the most commonly reported gastrointestinal bacterial disease, and is caused by the thermophilic Campylobacter spp bacteria. In 2007, the European Union incidence was 45.2 cases per 100 000 population (200 507 confirmed cases) and broiler meat as well as fresh poultry meat were the biggest identified sources of infections. Colonisation of broiler-chicken flocks with campylobacter increases rapidly with raising temperatures. The risk of campylobacteriosis is positively associated with mean weekly temperatures, although the strength of association is not consistent in all studies.
The second largest number of human food-borne diseases is caused by the Salmonella spp bacteria. In 2007, the European Union incidence was 31.1 cases per 100 000 population (151 995 confirmed cases) with eggs being the biggest contributors to these outbreaks followed by fresh poultry and pig meat. Higher ambient temperatures have been associated with 5-10% higher salmonellosis notifications for each degree increase in weekly temperature, for ambient temperatures above 5oC. Roughly one-third of the transmission of salmonellosis (population attributable fraction) in England and Wales, Poland, the Netherlands, the Czech republic, Switzerland and Spain can be attributed to temperature influences.
Temperature has the most noticeable effect on salmonellosis and food poisoning notifications 1 week before disease onset, indicating inappropriate food handling and storage at the time of consumption. Indeed, an analysis of food-borne illnesses from England and Wales showed that the impact of the temperature of the current and preceding week has decreased over the past decades, indicating that the potential risk from elevated temperatures related to climate change can be counteracted through concerted public-health action. Thus, regardless of climatic factors, health-behaviour interventions and food-safety regulations should be able to attenuate possible negative consequences on public health. Indeed, bacterial enteric infections have recently started to decrease throughout Europe, in part due to control measures.
Source: Semenza JC, Menne B. Climate Change and Infectious Diseases in Europe. Lancet ID. 2009;9:365-75.
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