The 2024 Nopales Botulism Case: Why Boiling Water Isn’t Pressure Canning

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In June 2024, eight people in Fresno County, California were diagnosed with foodborne botulism after eating a nopales (cactus paddle) salad made with home-preserved cactus. Six ended up in intensive care, and two needed mechanical ventilation to breathe. Every one of them recovered, but the case is a genuinely useful, well-documented example of exactly how botulism happens in home canning — and exactly why “I boiled the jars” is not the same thing as “I pressure canned it.”

What Actually Happened

According to the CDC’s own investigation, published in its Morbidity and Mortality Weekly Report, the person who made the salad prepared the nopales by immersing filled jars in boiling water, then added chopped, uncooked nopales mixed with a small amount of salt. The jars were then stored for six weeks in an outdoor shed before the salad was served. Symptom onset among the patients ran from June 23 to June 27, and all eight clinically diagnosed patients were hospitalized, with a median stay of four days and a range up to 42 days for the most severe case.

The Mistake, Broken Down

This case lines up almost perfectly with the textbook description of how Clostridium botulinum causes illness in home-preserved food, and it’s worth walking through each piece:

• Nopales is a low-acid vegetable. Like green beans, corn, and most vegetables that aren’t tomatoes or pickled in vinegar, cactus paddles don’t have enough natural acidity to stop C. botulinum spores from growing on their own. Low-acid vegetables require pressure canning, full stop — boiling water alone never gets hot enough.
• Boiling water tops out at 212°F at sea level. C. botulinum spores can survive boiling-water temperatures. Killing them requires the higher temperature only a pressure canner can reach — typically 240°F at 10–15 PSI, depending on altitude and canner type.
• Raw ingredients were added after the “sterilization” step. Immersing empty or partially-processed jars in boiling water and then adding raw, uncooked cactus afterward doesn’t sterilize the finished product at all — it just means the jar itself was hot, not that the food inside reached a botulism-killing temperature under pressure.
• Six weeks of storage in a shed, not a temperature-controlled space. C. botulinum is anaerobic, meaning it thrives specifically in the low-oxygen environment inside a sealed jar, and it doesn’t need refrigeration to grow — it needs time and the wrong temperature range, both of which six weeks in an outdoor shed provided.

Why This Isn’t a “They Should Have Known Better” Story

It’s tempting to read this as an obvious mistake, but the CDC report is useful precisely because the preparer clearly believed the boiling-water step made the product safe — the process had an active sterilization step, just the wrong one for a low-acid vegetable. This is exactly the confusion this site covers in our water bath vs pressure canning guide: high-acid foods like most fruits, jams, and vinegar pickles are genuinely safe with water bath (boiling water) canning, while low-acid vegetables, meat, and most mixed dishes are not, regardless of how long you boil them. The line between the two categories is about acidity, not about how much heat or effort went into the process.

How to Tell if Your Recipe Needs a Pressure Canner

If a recipe includes any low-acid vegetable — cactus, green beans, corn, carrots, potatoes, most squash — and isn’t heavily acidified with vinegar or lemon juice to a tested, published ratio, it needs a pressure canner, not a water bath or atmospheric steam canner. Our steam canning safety guide covers the one canner category that sometimes gets confused with pressure canning despite working at the same temperature ceiling as boiling water. A reliable pressure canner with a dial or weighted gauge is the only tool that reaches the temperature low-acid vegetables actually require — see our best pressure canners guide for options across price points.

What to Do If You’re Not Sure a Past Batch Was Safe

Botulism toxin doesn’t reliably announce itself with an off smell, a bulging lid, or a bad taste — some contaminated jars look and smell completely normal, which is part of what makes this bacterium uniquely dangerous compared to the spoilage organisms that cause visible mold or off odors. If you have any home-canned low-acid vegetables that weren’t processed in a pressure canner, the safest move is to discard them without tasting, following the boil-and-discard protocol described in our signs of spoiled home-canned food guide. Our rebel canning risks guide goes deeper into why shortcuts that “worked fine last time” don’t actually prove anything about safety, since botulism contamination is inconsistent even within the same batch.

Key Takeaways

• Eight people in Fresno County, California were diagnosed with botulism in June 2024 after eating home-preserved nopales that was processed by boiling-water immersion, not pressure canning; six required ICU care and two needed mechanical ventilation.
• The jars were also filled with raw, uncooked cactus after the boiling-water step and stored for six weeks in an outdoor shed — both compounding the underlying problem of using the wrong canning method for a low-acid vegetable.
• Boiling water tops out at 212°F at sea level, which is not hot enough to kill C. botulinum spores in low-acid foods; only a pressure canner reaches the required temperature.
• The preparer in this case wasn’t being careless — the process included a real sterilization step, just the wrong one for the food being preserved. This distinction is the whole reason acid level, not effort, determines which canning method is safe.
• Botulism-contaminated jars often look, smell, and taste completely normal; when in doubt about a low-acid vegetable processed without a pressure canner, discard it rather than taste-testing it.

FAQ

Can boiling jars in water for a long time make up for not using a pressure canner?
No. Boiling water tops out at 212°F at sea level no matter how long you boil it, and C. botulinum spores in low-acid foods can survive that temperature indefinitely. Only a pressure canner reaching roughly 240°F under pressure reliably destroys the spores.

Is cactus (nopales) the only vegetable this applies to?
No — nopales is simply the vegetable involved in this specific documented case. The same boiling-water-isn’t-enough rule applies to essentially all low-acid vegetables, including green beans, corn, carrots, potatoes, and most squash, along with meats and mixed low-acid dishes.

How would I know if a jar of home-canned low-acid vegetables is contaminated?
You often can’t tell by looking, smelling, or tasting — botulism toxin doesn’t reliably cause visible spoilage signs. If a low-acid vegetable was processed without a pressure canner, the safest response is to discard it without tasting rather than relying on how it looks or smells.