Hugh Pennington, professor emeritus at the University of Aberdeen and someone who has been around long enough in food safety to feel like he starred in Groundhog Day, writes in this opinion piece that on May 7, 1964, a catering-size can of corned beef from Rosario, Argentina, was opened in a supermarket in central Aberdeen. Half the contents were put on a shelf behind the cold meat counter and the other half went into the window.
The weather was warm. The sun shone on the meat. Corned beef is cooked in the can and should be sterile. But it wasn’t. It had been contaminated after cooking when the can was cooled with untreated water from the River Parana.
Into this river, 66 tons of human faeces and 250,000 gallons of urine were discharged every day from Rosario, where typhoid was common. The bacteria in the corned beef in the window grew vigorously.
The first person to fall ill developed symptoms on May 12. Making an initial diagnosis is not easy; it usually starts with a high fever, which can have many causes.
In Aberdeen the first definitive diagnoses were made on May 20. By midnight 12 were in hospital, and until June 13 daily hospitalizations never fell below double figures. The outbreak then fizzled out. At its end 503 had been admitted to hospital with typhoid, 403 with bacteriological confirmation.
Among those affected, there was a significant over-representation of women aged 15 to 25 living in the more prosperous west end of the city. The probable explanation is that a slimming regime incorporating cold meats and salad was popular at the time.
In 2011 in Germany, E. coli O104:H4, a brand-new bacterium that had evolved as a hybrid of two other disease-causing E. coli strains sickened more than 3,500, 855 developed serious complications and 53 died.
Just as in Aberdeen, the organism was imported. It came on the surface of fenugreek seeds which had left Egypt by boat on November 24 2009, eventually arriving at an organic sprout producer near Hamburg on February 10 2011.
Seed sprouting is ideal for bacterial growth. But identifying the seed sprouts as the cause of the outbreak was difficult and slow, because were used as a salad garnish and many victims were not aware that they had eaten them. That women were more commonly ill pointed to salads, but photographs taken at meals were invaluable.
It was all very embarrassing for the German public health authorities, particularly when the Hamburg health minister mistakenly announced that the organism that had caused the outbreak had been found on Spanish cucumbers, causing serous economic damage to that industry.
This mistake illustrated the limits of modern lab technology. We might now be in a position where we could genome-sequence E.coli O104:H4 quickly, but because it was a new strain, the authorities initially confused it for the more prevalent E.coli O157:H7. When they found this latter bug on the cucumbers, they thought they had found the culprit. New bugs will always make life difficult for scientists.
The German outbreak also pointed to another unavoidable issue: the Egyptians initially denied responsibility. Whatever your technological advances, politics is still likely to slow you down. One bright spot here though is that the Chinese are much more cooperative than they once were. This is vital given that the country’s size and relative concentration of people makes it quite a likely source for outbreaks.
Another important step forward has been global food safety standards. The worldwide adoption of the hazard analysis critical control points system – HACCP – originally developed by NASA to protect astronauts from food poisoning, makes it less likely that the world food supply could lead to a major epidemic – even if some countries are still more diligent than others.
Having said that, food poisoning is more common than a century ago (albeit not dysentry spreading from person-to-person or tuberculosis in milk). The Ministry of Health for England and Wales recorded 59 food poisoning incidents during the years 1931-1935, compared to more than 73,000 in 2012, itself a gross underestimate because most people with food poisoning don’t seek medical advice.
The number of sufferers from the UK’s number one cause, campylobacter, has been convincingly estimated at 500,000 people each year. To some extent this is down to better diagnosis, but probably not entirely. The realities of 21st century mass production of cheap meat are likely to have driven up infection, for example.
Above all else, the big lesson from Germany was that a major outbreak could still take us completely by surprise. With microbes evolving as they do, we can be certain it will happen again.