Three women who were hospitalized with botulism last year in New York City were sickened after eating potato salad containing improperly home-canned peas, an investigation found.

The women survived, but all three needed prolonged intensive care and rehabilitation, according to an MMWR report published today.

The patient who canned the peas that ended up in the potato salad was unaware of the correct procedure for safely canning vegetables, said Genevieve Bergeron, MD, a CDC Epidemic Intelligence Officer with the city health department, and colleagues.

“She used a peach preserves recipe with a boiling water technique, replacing the peaches with frozen vegetables. The patient was unaware that low-acid foods (eg, vegetables) must be canned in a pressure canner rather than a boiling water canner to eliminate [Clostridium] botulinum spores,” they wrote.

Three women were hospitalized with botulism after eating contaminated potato salad.

The women were hospitalized on June 6, a day after consuming the potato salad. Their symptoms — cranial nerve palsies and respiratory failure — suggested botulism, and they were treated with botulinum antitoxin released by the CDC, Bergeron and colleagues reported. They remained in intensive care for between 34 and 54 days.

Stool specimens from all three patients tested positive for botulism neurotoxin, as did a matching sample from the salad bowl. An investigation ruled out other ingredients and confirmed that the peas were the source of the infections.

“This outbreak illustrates the importance of educating home canners on safe home-canning practices to prevent botulism,” Bergeron and colleagues wrote. “Home-canned food, even when made with commercially processed ingredients, can lead to morbidity or mortality if canned incorrectly. Safe home-canning guidelines need to be followed, especially with low- acidity foods, and when processing errors occur, foods should be discarded or reprocessed according to recommended guidelines within 24 hours.”