“How do you like the point of the hamburger?” This question is increasingly common in many burger restaurants. In others they don’t even ask and they serve them directly undercooked or almost raw.
This is supposedly how you should eat them so that they are “juicier and we can enjoy their flavor more.” This is at least what some burger gurus and gastronomic influencers who have contributed to making them fashionable recommend. But this trend can pose a health risk. This has been warned for a long time by different organizations around the world, such as the Food Standards Agency (FSA) of the United Kingdom or the Spanish Agency for Food Safety and Nutrition (AESAN).
Two recent outbreaks help us keep this in mind. The first was recorded at The Champions Burger event held in Pamplona, in which at least 23 people fell ill. The second, which occurred in the United States, has so far left dozens of people affected and one dead, and is linked to the consumption of McDonald’s popular “quarter-pounder with cheese” hamburger. Details about the latter are still unknown, but the company has removed the sliced onion and pieces of meat, as they are suspicious ingredients.
What problem is there?
In these cases the main problem that we can find is the possible presence of Escherichia coli. It is a bacteria that is usually part of the intestinal microbiota of people and animals, especially ruminants, such as cattle. Most strains are harmless, but others can cause serious toxic infections in humans, as occurs with E.coli Shiga toxin producer, also known as STEC.
This bacteria can reach a hamburger through different means: contamination of the starting meat (for example, due to poor practices in the slaughterhouse), contamination due to poor food handling (for example, if the people in charge of preparing the hamburger do not wash their hands after going to the bathroom), or from contamination of other foods or utensils (for example, lettuce watered with contaminated water or a meat grinder that has not been cleaned well).
It can be very serious
What happens when contaminated food is ingested is that, after an incubation period of three to four days, the bacteria produces toxins that generally cause mild symptoms, with symptoms such as abdominal cramps, vomiting, nausea, moderate fever and acute diarrhea, which It is usually bloody, since these toxins damage the intestinal lining.
In most cases the disease is self-limiting and affected people recover after five or seven days. But in risk groups (under three years of age, pregnant women, elderly people and immunosuppressed people) complications may arise, such as pancreatitis, intestinal necrosis or hemolytic uremic syndrome. This last disease can occur especially in young children, elderly people and immunosuppressed people. It causes acute kidney failure, and is severe, to the point that it can be fatal in 3-5% of cases.
How risky is it?
Recently, the Finnish Food Authority (Ruokavitasto) carried out a study to estimate the number of poisonings that could occur due to the possible presence of E. coli when consuming undercooked hamburgers. It offers us two significant pieces of information. If 12% of the hamburgers were served rare (cooked to an internal temperature of 55 °C) there would be 100 cases per 100,000 inhabitants, while if all of them were served fully cooked, only 3 cases would be recorded per 100,000 inhabitants ( associated in this case with cross contamination). Another fact is that if all hamburgers were cooked completely, 178 people would get sick each year, while if they were served rare (cooked at 55°C for six minutes), the number of cases would multiply by 30.
It must be considered that this is data obtained from a predictive model, in the context of Finland. Possibly in Spain the results would be different (probably worse), because the conditions are also different, especially with regard to the climate, which, being warmer, favors the development of bacteria.
It is not the same as eating undercooked meat.
The risks associated with the possible presence of E.coli are linked to the consumption of undercooked hamburgers and also to other dishes made with minced or chopped meat that is served raw or undercooked, such as steak tartare or carpaccio. But this does not happen with whole pieces, such as sirloin, entrecote or ribeye, even if they are undercooked.
In a whole piece of meat, like the ones we just mentioned, the bacteria can only be found on the surface, so it is eliminated during cooking, due to the high temperatures reached in that area.
But when a piece of raw meat is minced or cut to obtain minced meat, the bacteria, which were initially only found on the surface of that piece, end up contaminating the entire product. That is, in a hamburger these bacteria are not only on the surface, as is the case in a whole piece of meat, but they can be found inside. So, if it is not cooked enough, until it is well done on the inside, those bacteria can survive and make us sick. It must also be considered that its infective dose is low (only 100 bacteria are needed to cause the disease).
How to avoid risks
The easiest way to reduce the risks associated with the possible presence of E.coli In hamburgers it consists of cooking them sufficiently, that is, until they reach a temperature of at least 70 °C inside. This eliminates the bacteria and inactivates the toxin.
This measure alone is not enough. We must also follow other basic recommendations that we must put into practice when handling any food: wash hands and utensils well, separate dirty or raw foods from those that are already clean or ready to eat, keep meat at refrigeration temperatures until the time of cooking and respect the duration date.
It is not recommended to consume hamburgers rare, but if we insist on doing so, it is advisable to take these measures to the extreme and also adopt additional ones. It is recommended to make the burger from a whole piece of meat, fresh and in good condition, and chop it immediately before making it. Before chopping the meat, it is advisable to cut and remove the superficial parts so that we only have the internal part. Another even better option: you can lightly cook the surface of the entire piece, so that the heat eliminates the possible presence of bacteria, and then cut and remove that superficial part to later chop the internal part. Once the surface part has been removed, the internal part should be chopped or chopped as soon as possible and the burger prepared as soon as possible to serve it immediately after it has been prepared.
In this way, risks are reduced, but not eliminated. That is why it is recommended that people belonging to risk groups (young children, pregnant women, immunosuppressed people and the elderly) avoid eating undercooked hamburgers.
Restaurant establishments must also apply other measures, included within the food safety management system, such as carrying out microbiological analyzes of surfaces, maintaining control of suppliers or having appropriately trained personnel for food handling. It is also advisable to warn about the risks associated with this food, especially for people belonging to risk groups.
They are not only in the flesh
The pathogenic strains of E.colilike STEC, are not only associated with the consumption of raw or undercooked minced beef. There is also a risk in other foods, if proper precautions are not taken, especially those that are not cooked or not heated sufficiently before being consumed, such as raw milk, fresh vegetables, sprouted seeds or unpasteurized fruit and vegetable juices. .
It is enough to remember two important, relatively recent food crises that also show the potential seriousness of this bacteria.
The first, recorded in Germany during 2011, affected more than a thousand people and left 54 dead. At first, it was erroneously linked to the contamination of cucumbers from Spain, but finally it was associated with the consumption of sprouted seeds.
The second crisis occurred in France during the year 2022 and was due to the consumption of contaminated pizzas. It affected at least 75 people and generated a huge stir throughout Europe, because it was a well-known brand (Buitoni, belonging to Nestlé) and because it caused the death of two young children.
Cases in Europe and Spain
Toxiinfection by Shiga toxin-producing E. coli (STEC) is a notifiable disease in almost all countries of the European Union, also in Spain. In 2022 it was the fourth most important zoonosis in Europe, behind campylobacteriosis, salmonellosis and yersiniosis. In Europe, 71 food-associated outbreaks were recorded, three of them in Spain, which affected more than 7,100 people (2.1 cases per 100,000 inhabitants), of which 18 died.
In Spain, 633 cases were registered during that same year, with 134 hospitalizations and three people dying: a child under three years of age and two adults aged 65 and 93.
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