Climate Change May Affect Food Poisoning Outbreaks
Source : http://foodpoisoningbulletin.com/2012/climate-change-may-affect-food-poisoning-outbreaks/
By Linda Larsen (Apr 04, 2012)
Scientists predict many consequences to climate change, such as changes in weather patterns and severity of storms. But a new report titled Assessing the Potential Impacts of Climate Change on Food and Waterborne Diseases in Europe ties climate change to increases in food poisoning outbreaks.
The report is an assessment of 741 peer-reviewed publications, reports, and scientific sources. From these, the researchers found 1653 “key facts” linking food and waterborne illness pathogens with climate variables.
Climate scientists say that global mean air temperatures are projected to increase by 1.1 to 6.4 degrees C (2 to 11.5 degrees F) this century. Public health is affected by these changes, such as deaths in heat waves, flooding, and increases in illnesses because of shifting distribution of communicable diseases.
Food and waterborne disease incidence is linked to precipitation levels and ambient temperature increases. Higher temperatures accelerate pathogen growth. Extreme rain events can increase the pathogen flow into the water supply. And extended warm weather seasons can compound food handling mistakes.
The identified climate variables included:
■Water temperature
■Seasonality
■Air temperature
■Heavy rainfall events
■Precipitation
■Temperature changes
Many food poisoning outbreaks are linked to improper food handling and storage. For instance, perishable food should not be held out of refrigeration longer than two hours. But that time is cut in half as the temperature increases. When the ambient air temperature is over 90 degrees F, perishable food can be out of refrigeration for only one hour.
These pathogens were linked to climate variables in the literature.
■Campylobacter is the source of the most prevalent food and waterborne disease in Europe. Most cases are caused by eating raw or undercooked poultry, unpasteurized milk, or contaminated water. The report found that Campylobacter outbreaks show strong seasonality. Outbreaks were cited with the highest frequency in association with air temperature, but the strength of association was not consistent. And Campylobacter outbreaks are often associated with weather events. The peaks of these outbreaks may change as a result of climate change.
■Salmonella infections are more common in summer than winter. The most common sources of this bacteria are from raw poultry, ground beef, eggs, and unpasteurized milk.
Salmonella was also cited with high frequency in associated with air temperature. Improper food storage and handling are common causes of salmonellosis. Some scientists think that one-third of salmonellosis cases are caused by increased air temperature. In fact, scientists have found that for every degree the air temperature rises above 43 degrees F, salmonellosis cases rise 12%. But the report found that salmonellosis incidence has decreased throughout Europe, most likely because of public health measures.
■Cryptosporidium is a parasite found in drinking and recreational water. Most people contract it by swallowing water contaminated with the parasite. Many studies have linked the transmission of Cryptospordium with heavy rainfall events, surface water, and tap water, so the researchers predict that unexpected precipitation events will increase cryptosporidiosis outbreaks. Since severe storms can overwhelm water treatment facilities, Cryptosporidium contaminations may increase.
■non-cholera Vibrio bacteria are in the same family as the bacteria that cause cholera. People who eat contaminated seafood or have an open wound that is exposed to seawater can contract the disease. Ulceration, skin breakdown, and, in rare cases, septicemia can occur when the bacteria enter open wounds. There is a strong association between rising water temperatures, higher air temperature during longer summer seasons, and non-cholera Vibrio infections. But the researchers found that because the incidence of this bacteria is low, an increase in diseases will be modest.
■Listeria is found in soil and water. Foods that have been contaminated with Listeria include produce, ready-to-eat foods, unpasteurized milk and cheeses, and uncooked meats. This bacteria as a source of infection wasn’t associated with any of the climatic extremes in any report. The report authors believe that climate change is not likely to influence listeriosis outbreaks, but indirect pathways could result in more cases.
■Norivirus causes many cases of gastroenteritis every year because it is very contagious. It is spread through person-to-person contact. One sick person preparing food for a group can infect many people. It is most common in the winter months when people are forced into close contact. But the report says that there is little published information about a connection between climate and Norovirus outbreaks.
The researchers mention that quantitative modeling studies should look at the strength of association between pathogens and climate variables. The frequency of association between climate variable and pathogens in the report is a “possible, albeit imperfect, proxy for strength of association.”
The report concludes that Campylobacter, Salmonella, and Cryptosporidium should be high priority for future studies and planning for climate changes. Outbreaks of illness caused by these pathogens have a strong public health impact and their incidence is strongly associated with climate change.
The report did acknowledge publication bias in the studies, since reports written in English and German were most often used. The authors also say that underreporting and lack of information on the connection between climate change and food and waterborne illness outbreaks could be a risk to public health. The authors hope that the decline in Salmonella infections because of public health efforts can be replicated with other pathogens, even if climate change causes incident increases