Botulism Outbreaks in Europe Raise Food Safety Concerns

In September this year in Rome, an older woman died, and her daughter spent a week in intensive care after eating a few spoonfuls of a frozen artichoke soup bought at their local supermarket. Only days earlier, in France, five people were hospitalized after eating pesto.

Their food was contaminated with botulinum toxin, the neurotoxic protein produced by the bacterium Clostridium botulinum. “Botulinum is the most dangerous natural poison that we know of,” Fabrizio Anniballi, PhD, lead of the National Reference Centre for Botulism at the Italian National Institute of Health in Rome, Italy, told Medscape Medical News.

In 2023, 112 cases of botulism were reported in Europe, with Italy registering the highest number, followed by France, Spain, Romania, and Germany. Most North European countries reported no cases. “Case numbers and the type of botulism vary between countries depending on dietary habits, culinary traditions, and food preparation methods,” Taina Niskanen, PhD, European Centre for Disease Prevention and Control expert on food- and waterborne diseases, told Medscape Medical News.

What Is Botulism and Why Is It So Dangerous?

The toxin produced by the bacterium C botulinum attacks the body’s nervous system, blocking the release of acetylcholine, a neurotransmitter responsible for muscle contraction. Symptoms include muscle weakness, paralysis, and respiratory difficulties, which can be fatal. “Even a small amount of contaminated food can cause the disease,” said Anniballi. He explained that the disease is rarely deadly, but it needs to be recognized and treated promptly with an antitoxin and can still have severe consequences.

There are several forms of botulism, but the most common is foodborne, especially via contaminated improperly preserved food or improperly stored frozen food. The bacterial spores thrive in low-oxygen environments, low acidity, and specific temperature ranges. And while the toxin is heat sensitive, the spores are highly resistant.

Why Do Some Countries Have More Cases Than Others?

Anniballi explained that there are three primary factors contributing to the ongoing challenge of botulism. First, the presence of C botulinum in the environment is highly variable across different countries, with certain regions having higher levels of the bacterium in soil and water.

A second significant factor is difficult detection and surveillance. Botulism is a rare disease that may not be quickly recognized or reported, particularly in regions with less robust foodborne illness surveillance, Anniballi said. This can impede accurate assessment of the disease’s incidence and distribution, complicating efforts to control its spread.

Lastly, cultural factors play a role. Traditional home canning is still prevalent in some countries, but methods may not always adhere to rigorous safety standards. Italy, where home canning has old roots, is the European country with the highest number of reported cases each year. In 2023, Italy reported 36 cases of botulism, half of which were caused by improper home canning. It was followed by France with 15 cases and Romania and Spain with 14 cases each. “Italy, Spain, France, Poland, Romania, all have a strong tradition in [home] preserving and canning food,” said Anniballi.

What Can People Do to Stay Safe?

Niskanen said that people should be careful when preserving foods at home to minimize the risk for botulism. Proper hygiene practices and trusted instructions for safe home canning are essential to prevent contamination. “People should be aware of the risks of botulism associated with certain foods,” she said. “Do not eat preserved food if you do not know it was safely produced or there are signs of contamination, like the container is damaged, leaking, or swollen.”

Anniballi pointed out that industrially canned foods are generally safer than home-canned foods because industrial processes follow strict standards. However, consumers should still be cautious because any failure in sterilization can pose a risk. “Risk-zero does not exist,” he said.

He suggested that refrigerated and frozen processed foods with short shelf lives often lack preservatives and are minimally heat treated. Boiling them for at least 5 minutes before eating can inactivate any botulinum toxins that may be present.

Maintaining the cold chain is also crucial. Proper refrigeration must be observed from production to storage, as breaks in the cold chain can encourage the growth of C botulinum.

Finally, he said, paying attention to cooking instruction labels is essential. European food safety legislation mandates that safety information be included on food labels, particularly for foods requiring special preparation or specific storage conditions. However, not all countries have clear labeling.

In Italy, for instance, labels on refrigerated foods are sometimes imprecise. “In certain cases, labels may indicate that a mild thermal treatment is sufficient, even though such treatment may not be enough to inactivate botulinum neurotoxins,” Anniballi said. “We are working with the [Italian] Ministry of Health and industry organizations to develop clearer, more precise labeling to inform consumers better.”

What Can Doctors Do?

Niskanen said diagnosis can be challenging. “Symptoms of botulism vary depending on the type of toxin, the age and preexisting conditions of the patient, and the amount of toxin consumed.”

Because symptoms can escalate quickly and become severe, clinicians should be prepared to provide intensive care treatment and administer antitoxin promptly, she said.

Lastly, investigating and identifying the source of infection, prompt reporting, and collaborating with public health authorities can avoid more cases.

Anniballi and Niskanen disclosed no relevant financial relationships.

Manuela Callari is a freelance science journalist specializing in human and planetary health. Her words have been published in The Medical Republic, Rare Disease Advisor, The Guardian, MIT Technology Review, and others.