Salmonella: a growing problem when the mercury rises

by Stefanie Willstein

            Today’s environmental gurus put an immense amount of pressure on citizens of the world to help in the fight against global warming.  We see this issue in our every day lives – on the news, in documentaries, when we think about what cars to buy.  However, did it ever cross your mind that an increase in temperature can affect your life more than society tells you it can?  A problem could be growing right under your nose, and you would not even know it.  That problem is a bacterium known as Salmonella. 

            The salmonella bacterium is responsible for more deaths per year than any other bacteria growth in food (particularly in England).  There are more than 2500 variations of salmonella existing today.  The most commonly occurring strains include S. Typhimurium and S. Enteritidis.  In European nations, those two food borne pathogens are held accountable for upwards of 70% of all food poisoning (Kovats et al, 2004).

Many research studies have examined the affect of rising ambient temperature on food contamination (specifically looking at the growth of Salmonella).  Not only does rising temperature have an affect on the growth of this harmful bacterium, but the fact that global warming is causing the weather to stay warmer longer increases foods proneness to salmonella bacteria.  Summer time activities, such as barbecuing, increase our chances of contaminating our food (Kovats et al, 2004).  For example, touching the cooked chicken with utensils used to cook the raw chicken could contaminate the finished product.  Cooking kills the salmonella bacteria, but with the temperature on the rise, salmonella grows more often in raw meat. 

In the year 2004, a study done by R.S. Kovats and colleagues was conducted in order to examine the relationship between the increase in temperature and the noticeable increase in cases of salmonella poisoning in ten different European countries.  Weekly reports of salmonella infections that were received through questionnaires were analyzed.  It was concluded that in 35% of salmonella cases, temperature was a prime influencer on the presence of the bacteria (Kovats et al. 2004).  Adults between the ages of 15 and 64 illustrated the linear relationship between temperature and salmonella illnesses the most (Kovats et al. 2004). 

Associated with the most recent IPCC report is a similar study done by Rennie M. D’Souza and colleagues on the relationship between temperature and food borne illnesses.  In Australia between 1991 and 2001, the experimenters observed all reported cases of salmonella illnesses from the capital cities (D’Souza et al. 2004).  It was also concluded in this study that there was a positive association between the ever rising temperature and the ever-increasing reports of salmonella related illnesses.  Mean temperature from the previous month was directly associated with salmonella reports in the following month.  Another study was conducted in Canada during a similar time period (1992 and 200) by Manon Fleury and colleagues.  These scientists studied the association between ambient temperature and food borne illnesses on a weekly basis.  Not only was salmonella under their watchful eyes, but so was Escherichia coli and Campylobacter (Fleury et al. 2006).  It was found that there was a strong non-linear association between ambient temperature and the food borne illnesses.  Weekly reports of illness, for the most part, increased as temperature rose (Fleury et al. 2006).    

Recent reports and studies of this illness causing bacteria may be somewhat distressing to readers.  However, there are many precautions that the general public and food manufacturers can take in order to ensure that food will not become contaminated during those months of higher temperature.  Commercial food outlets, it has been suggested, need to be continually informed of the risks of not properly storing or handling uncooked food.  All food which needs to be refrigerated must be kept at the appropriate temperature so that it will not spoil.  Food can also be kept safe in the household by thoroughly cooking it and properly storing it when it is raw.  Make sure to use separate utensils for raw meat and cooked meat, as to not contaminate the ready-to-eat food. 

References

D’Souza, R., Becker, N., Hall, G., and Moddie, K., 2004: Does ambient temperature affect foodborne disease?  Epidemiology, 15, 86-92.

Kovats, R.S., Edwards, S.J., Hajat, S., Armstrong, B.G., Ebi, K.L., Menne, 2004:  The effect of temperature on food poisoning: a time series analysis of salmonellosis in ten European countries.  Epidemiology and Infection, 132, 443-453.

Manon, F., Charron, D.F., Holt, J.D., Allen, O.B., Maarouf, A.R., 2006: A time series analysis of the relationship of ambient temperature and common bacterial enteric infections in two Canadian provinces.  International Journal of Biometeorology, 50, 385-391.