Microbiologists warn that more people are likely to suffer from food poisoning in the future as humid temperatures become more common due to climate change.
The bacterial strain called Salmonella enterica– better known as salmonella – causes illness in an estimated 1.2 million people in the United States each year, according to a study published today.
“Climate change will increase the risk of foodborne illness from eating raw foods,” said study author Professor Jeri Barak of the University of Wisconsin-Madison in a statement.
Salmonella food poisoning can cause nausea, vomiting, diarrhea, cramps, fever, chills, headache, fatigue, dizziness, and possibly death.
The most common source of infection is the consumption of contaminated fresh produce. However, there are a number of factors that can influence whether salmonella is present in our food. These factors were the subject of the microbiologists’ study.
They found that plants infected with other strains of bacteria are more susceptible to Salmonella, and that humid environments—which are likely to become more common as a result of climate change—can encourage the emergence and growth of both strains of bacteria.
“It’s not surprising that a host is altered by a disease,” Barak said. “What’s interesting is how these changes affect not only the pathogen but also other members of the bacterial community.”
“In addition, increased humidity also promotes the survival of Salmonella on plants, which would make climate change a concern for food safety.”
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The microbiologists investigated the conditions that allowed salmonella to survive in romaine lettuce, depending on environmental factors – such as humidity – and whether and how they interact with another bacterial strain called Xanthomonas hortorum pv. Vitianer (X. Vitian).
X. Vitian is a common threat to leafy vegetable production and causes a defect in lettuce called bacterial leaf spot.
The researchers conducted experiments in which they infected lettuce with X. Vitian and then introduced Salmonella via a water droplet on a leaf to simulate the plant being splashed with infected water from the ground.
They varied the day of introduction of salmonella according to X. Vitian and found that there was a sweet spot: too early, and the salad’s defenses were on guard X. Vitians, Limiting the survival of Salmonella; too late and the lettuce would have succumbed to the disease and the Salmonella would have struggled to grow and survive.
However, higher humidity always helped X. Vitian and salmonella to settle on the salads and thrive. Even if X. Vitian had to contend with humid temperatures that favored the growth of salmonella.
Barak said controlling plant diseases such as bacterial leaf spot is important for food safety.
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reference
Dixon, MH, Nellore, D., Zaacks, SC, & Barak, JD (2024) Arrival time during plant disease progression and moisture additively influence Salmonella enterica Colonization of lettuce. Applied and Environmental Microbiology, 90(8). https://doi.org/10.1128/aem.01311-24
