Certain bacteria can be major spoilsports at barbecues. They can have serious consequences for pregnant women and immunocompromised people.
“Once a grilled sausage is cooked all the way through, Listeria no longer poses a risk,” explains Miriam Vázquez, senior physician at the Department of Infectious Diseases and Hospital Hygiene. The bacteria are killed by the heat. However, it is not juicy steaks that are problematic, but pre-processed grilled sausages. Accordingly, the Federal Hygiene Regulation establishes process hygiene and safety criteria for various food products.
“During the processing of animal products, Listeria bacteria may be present on surfaces.” “Rigorous and controlled hygiene is therefore essential.”
Salmonella as the leading cause of food poisoning
However, salmonella is by far the biggest cause of food poisoning in terms of the number of cases. Enteritic salmonella is one of the most common causes of diarrhea. Food poisoning occurs after consumption of animal foods – milk, raw eggs or undercooked chicken or fish – and is usually due to incorrect storage or preparation. In addition, germs can multiply rapidly at room temperature. Within 20 minutes the number of bacteria doubles, after 40 minutes their number has quadrupled.
Proper food storage is therefore important. Listeria can continue to multiply even at refrigerator temperatures. Miriam Vázquez explains: “With Listeria, fewer than ten bacteria are enough to cause illness.” Nevertheless, listeriosis is rare in Switzerland. The most well-known cases of listeriosis in Switzerland have been linked to cheese products made from raw milk.
In brief
Food contaminated by salmonella is predominantly of animal origin. These pathogens can multiply at room temperature. Strict food hygiene is therefore important. Listeria infections usually occur after the consumption of raw milk products. Anyone who is pregnant or immunocompromised should avoid these products.
In the case of food poisoning caused by salmonella, the person falls ill within a few hours. The cunning Listeria, on the other hand, take their time. The incubation period is between three days and several weeks. “When there is an increase in cases of illness, it often requires detective work and an investigation into the causes,” says Miriam Vázquez. It is not without reason that diseases caused by listeria are notifiable.
At particular risk: pregnant women and people with weakened immune systems
Sick people with an intact immune system suffer from diarrhea, sometimes accompanied by fever. Immunocompromised and pregnant women are more susceptible to serious Listeria infections: Bacteria can be washed into the brain via the bloodstream, causing meningitis and miscarriages. Hospitalization is then necessary and the patients are treated with antibiotics. “It is advisable to avoid consuming raw milk and raw-milk cheeses for the entire nine months of pregnancy,” Miriam Vázquez advises. Well-cooked sausages are not a problem. Similar recommendations apply to immunocompromised people.
