What Kind of Botulism Accounted for the Majority of Confirmed Cases in 2015?

The Centers for Disease Control and Prevention (CDC) recently released a national surveillance summary for 2015 on a rare, but serious, paralytic illness: botulism. The illness should ring familiar as it made headlines recently as the cause of an outbreak in Sacramento, California, that was traced back to contaminated nacho cheese served and sold at a local gas station.

According to the CDC, botulism is “caused by a toxin that attacks the body’s nerves and causes difficulty breathing, muscle paralysis, and even death. This toxin is made by Clostridium botulinum and sometimes Clostridium butyricum and Clostridium baratii bacteria. These bacteria can be spread by food and sometimes by other means.” There were a total of 199 confirmed and 14 probable botulism cases in the United States in 2015. The total of confirmed cases is up since the previous year, 2014, when only 161 confirmed botulism cases had been reported.

The authors of the report also shared that infant botulism accounted for the majority (71%) of the confirmed cases. Infant botulism “can happen if the spores of the bacteria get into an infant’s intestines,” according to the CDC. Once in the intestines, the spores have the potential to grow and produce the toxin, which results in illness. Infant botulism cases were reported from 33 states as well as the District of Columbia, with the median age of the patients being 2.7 months old. The authors also noted that toxin type B was responsible for the majority of the cases, 56%. No deaths related to infant botulism had been reported in 2015.

In 2015, food-borne botulism accounted for 20% of the confirmed cases (see Table 2a), and had been reported from a total of 7 states. For this kind of botulism, the median age of patients was 59, with a wide range of 9 to 92 years. According to the report, there were 5 food-borne botulism outbreaks in 2015, which accounted for 37 cases collectively. One outbreak was linked back to contaminated home-canned potatoes used in a potato salad provided at a church potluck, another outbreak was associated with fermented seal flipper, and another outbreak was linked with roasted beets used in a soup. The food-borne sources for those last 2 outbreaks remain unknown. The authors also noted that toxin type A was responsible for the majority of the foodborne cases, or 87%, and one death was reported.

Another kind of botulism, wound botulism, accounted for 8% of confirmed cases for 2015, which had been reported from 5 states. The patients ranged in age from 12 to 61 years old, and the median age of those infected was 49 years. Again, toxin type A accounted for the majority of the cases (93%). The authors also noted that 93% of the individuals who were infected with wound botulism were injection drug users. According to the CDC, those who inject illicit drugs, “especially black tar heroin” under the skin or into a muscle, are at increased risk of wound botulism infection. One death due to wound botulism was reported.

The authors also noted that “botulism of unknown or other transmission category” accounted for 2% of the confirmed cases and had been reported in a total of 3 states. For this group, the median age of those infected was 47 years, with an age range of 27 to 71 years. Toxin type A was responsible for all of these cases. Although the route of transmission for these cases is unknown, the authors note that 2 cases “were suspected to be adult intestinal colonization,” which is a “rare form of botulism thought to have a similar mechanism as infant botulism.” The other 2 cases did not have any risk factors for adult intestinal colonization; the individuals did not consume a “suspect food,” and did not have any wounds. For this group, 1 death was reported.

Although botulism is rare, the illness can have serious implications such as breathing difficulties, muscle paralysis, or death. Food-borne botulism can be prevented and safety tips for handling and preparing common foods to prevent botulism are available on the CDC website. Pratitioners should advise their patients who partake in home canning, to be particularly careful, because if the process is not done properly, canned vegetables and fruits can potentially cause botulism. Therefore, following the proper techniques, using the right equipment, and throwing out any suspect food, is imperative.