The United States is currently facing a significant outbreak of cyclosporiasis, the largest on record. Thousands of individuals, mostly in the Midwest, are experiencing severe stomach cramps and diarrhea. The illnesses linked to this outbreak have been traced back to lettuce grown in Mexico and used in some Taco Bell locations.
This week, my colleagues on the Well team have been following the investigation into the outbreak, which took an unexpected turn.
On Saturday, the Food and Drug Administration (FDA) announced that lab tests confirmed the presence of cyclospora in iceberg lettuce from Mexico. The company involved, Taylor Farms, issued a recall initially based on epidemiological evidence and later expanded it following the lab findings. However, by Sunday, the FDA reported that the test results were a false positive. Yet, Taylor Farms remains a focal point of the investigation, and the recall is still in effect.
The role of climate change in this outbreak is still uncertain. Cyclospora spreads through human feces, and it can be quite challenging for investigators to identify the specific source of contamination.
Experts suggest that rising temperatures might play a role in the increase of cyclospora cases. Don Schaffner, a food microbiologist at Rutgers University, mentioned that cyclospora thrives in warmer months, which might extend its growth season. In past outbreaks, some investigators have speculated that heavy rains could lead to human waste contaminating irrigation sources, thus affecting crops.
While the link between this outbreak and climate change remains unclear, it is expected that warming temperatures will contribute to the spread of various foodborne pathogens. This situation has also highlighted weaknesses in public health monitoring systems, which are becoming increasingly crucial as accurate food supply tracking is needed.
Higher temperatures, more illness
The World Health Organization reports that around 600 million people worldwide get sick each year from consuming contaminated food. Research indicates that climate change is likely to increase the number of cases in numerous regions.
Increased temperatures and rainfall are both linked to higher rates of illnesses caused by pathogens like salmonella and campylobacter. This is partly because warmer conditions allow germs to multiply more rapidly. For instance, salmonella thrives when temperatures are in the 90s Fahrenheit, making it easier to grow in animals or on food. A study from 2014 in Mississippi showed that even a one-degree Fahrenheit increase could lead to more salmonella cases.
Warming oceans add another layer of risk to food safety. A paper published in 2024 highlighted that climate change is undoubtedly contributing to the spread of bacteria such as Vibrio, including the notorious Vibrio vulnificus, which can lead to serious infections from eating raw seafood or swimming in tainted waters.
Dry spells and intense rainfall can also facilitate the spread of pathogens. During drought conditions, dust can carry bacteria across farmlands, while heavy rains can wash human and animal waste to different locations, increasing contamination risks. Tropical storms, which are likely to become more frequent due to climate change, are correlated with significant spikes in E. coli infections.
The ‘big concern’ for public health
It’s quite rare for the FDA to retract a positive lab test announcement. Dr. Schaffner commented that the agency may have jumped the gun with their statement before completing comprehensive testing.
“Now they’ve got egg on their face, and nobody’s happy,” he remarked.
In a statement, an FDA spokeswoman noted that the agency has mounted a strong response to the outbreak, providing necessary information for public safety.
The back-and-forth has left many confused about which foods to steer clear of. The retraction didn’t signal a shift from investigating Taylor Farms and lettuce, yet the company stated that the FDA apologized to them; however, the FDA denied having made any such apology, as reported in the news.
“My main concern with this back-and-forth is its impact on public trust,” Dr. Susan Mayne from Yale School of Public Health shared. “Such a significant change raises quite a few questions,” she added.
Federal budget cuts to health funding might also be affecting the response to this outbreak. State and local health departments, which depend on federal funding for monitoring foodborne illnesses, received less than half of what they requested this year.
Not long ago, several states were mandated to track and report cyclospora cases to a national database, but this was made voluntary last year by the Centers for Disease Control and Prevention. This incomplete data likely made it more challenging for officials to identify the outbreak in time.
“This certainly doesn’t help our ability to manage cyclospora effectively,” Dr. Schaffner noted.
