An image in the CDC's most recent Morbidity and Mortality Weekly Report shows preserved nopales identified as the source of one of California's largest botulism outbreaks that occurred in Fresno County a year ago. Image via MMWR

A botulism outbreak tied to canned cactus in Fresno County a year ago was featured in a recent federal report highlighting the response from local health officials that helped save eight lives.

The Fresno County Department of Public Health (FCDPH) was included in the Center for Disease Control and Prevention (CDC)’s latest Morbidity and Mortality Weekly Report (MMWR) in an article titled: “Foodborne Botulism Outbreak After Consumption of Home-Canned Cactus (Nopales) – Fresno County, California, June 2024.”

The new report highlights the successful local botulism response that saved eight lives, according to an FCDPH news release. The report series is the CDC’s primary vehicle for scientific publication of timely, reliable, accurate, objective and useful public health information and recommendations.

The outbreak tied to food served at family events on June 21, 2024 in Caruthers and the next day in Clovis made national news. An investigation was launched on June 24 that included Fresno County health officials, two local hospitals, the CDC and California Department of Public Health. Investigators determined the botulism outbreak was tied to home-preserved prickly pear cactus pads, called nopales, that were served in a homemade salad. A total of 31 people attended one or both gatherings.

Eight attendees had symptoms compatible with botulism and received antitoxin to combat the bacteria-caused illness. Five of the eight had botulinum neurotoxin detected in their blood, with patients requiring hospital stays ranging from 2 to 42 days.

Six patients were admitted to an intense care unit, and two required invasive mechanical ventilation – but all survived.

The CDC report notes this is the first foodborne botulism outbreak linked to the home canning of nopales, which is a popular vegetable used in Mexican cuisine.

The report outlines the official response that included a public health alert for the health care community followed by a news release to the media. The CDC distributes botulinum antitoxin from so-called “port health stations” located at major U.S. airports. The doses delivered by helicopter to a Fresno airport and then to the local hospitals with help from the California Highway Patrol temporarily depleted the state’s supply of antitoxin for a period of 48 hours, according to the report.

Botulism is a rare and potentially fatal illness, and it can be challenging to recognize the early signs. In fact, the first patient to be evaluated at a hospital – a 42-year-old woman – received an initial diagnosis of health-related dehydration and was discharged.

She returned again the next day but was not evaluated. By the third visit, she was admitted with symptoms including persistent dizziness, blurry vision, a drooping eyelid and difficulty swallowing. Within six hours of arriving at the hospital that day, she was receiving mechanical ventilation because of impending respiratory failure.

The report states that the clinical diagnosis of botulism requires “a high index of suspicion,” requiring a meticulous food and exposure history and physical examination of the paralysis that accompanies the illness in patients, according to the report.

Health departments and partner organizations can also play a role in educating communities about proper home preservation and canning techniques, according to the report.

“Enhancing community and clinician awareness of foodborne botulism by increasing access to culturally and linguistically accessible home food preservation and canning guidelines might help prevent future outbreaks, said the report.