As reported on barfblog.com (with, as ever, an entertaining title: You see a cute turtle, I see a bug factory: Infant botulism from C. butyricum) a recent paper in the journal Epidemiology and Infection (Shelley et al. 2015) reports an unusual turtle-associated disease.
When we think about turtles and infections (especially infections of young kids), the first thing that comes to mind is Salmonella. That’s fair because it’s common and can be serious. However, like any animal, turtles can carry a range of microbes that can infect people. Apparently, we need to add the bacterium Clostridium butyricum to the list.
The paper describes botulism in two infants caused by this bacterium and related to turtle exposure. Botulism is classically caused by Clostridium botulinum, a bacterium that can produce some of the most potent neurotoxins known to science. However, a couple of other bacteria, including C. butyricum, can produce similar toxins and cause the same disease. Infants are highly susceptible to disease caused by ingestion of the bacterium, since it is able to grow in their gut because of their poorly developed intestinal bacterial flora. (In more mature individuals, botulism isn’t usually caused by ingestion of the bacterium itself. Rather, it’s caused by eating food that contains the toxin that was produced when the bacterium was able to grow in the food).
The first case was an 11-day-old boy that was presented to a hospital with various neuromuscular abnormalities. As is common, he had to be put on a ventilator to help him breathe, but fortunately he made a full recovery over the next 10 days. Botulism was suspected early in the course of disease and he received antitoxin (antibodies against the toxins), which probably played a key role in his response. However, C. butryicum, not C. botulinum, was identified in his stool and it was confirmed that the bacterium was able to produce botulinum toxin E.
The second case was a child of about the same age admitted to hospital with breathing problems and a few other issues. Botulinum toxin E was found in his stool, and C. butyricum was isolated.
Investigation of possible sources of the bacterium ensued. Various food and environmental surfaces, plus feces from the parents, were tested. For the first boy, C. butyricum was isolated from his mother’s feces, as well as their turtle aquarium water, sediment and turtle food. The same batch of food from the pet store was negative, so the food was probably contaminated in the house.
The only positive location in the second child’s case was the turtle tank water in a relative’s house, not the child’s house. The relative had held and fed the baby.
These cases also led to a review of a case of C. butyricum botulism that had occurred in 2010. It was assumed to have been caused by honey ingestion, but further investigation revealed the presence of the same type of turtle (yellow-bellied terrapin) in the house.
This report doesn’t change anything in terms of recommendations regarding how to manage turtles, but is good to raise awareness. Turtles should not be in households that have kids less than 5 years of age, for multiple disease reasons. Infection of the second child via a relative who owned turtles raises concern about how pathogens can be spread indirectly from turtles to high-risk individuals. The relative was reported to have put her finger in the baby’s mouth to soothe him at one point, and that would be a logical source of exposure, highlighting the need for good hygiene practices after having contact with animals and their environments, especially high-risk species such as turtles.
As the authors conclude “Adherence to advice that reptiles, including terrapins, should not be kept as pets in homes where there are children aged <5 years, primarily to prevent salmonellosis, would also prevent cases of infant botulism associated with terrapins. The importance of hand washing after handling these pets also needs to be stressed, especially while visiting families with small children.”