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