Botulism toxin is produced by the bacterium Clostridium botulinum, an anaerobic, gram positive, spore-forming rod. Foodborne botulism was first described by Justinus Kerner in 1820, after 230 people suffered "sausage poisoning" in Württemberg, Southern Germany (2).
The bacterium was identified in 1897, and was then named Bacillus botulinus after the Latin word for sausage - botulus (3). Generally speaking, botulism comprises three different disease pictures: foodborne botulism, infantile botulism and wound botulism. In rare cases, iatrogenic botulism also occurs in patients who have received botulinum toxin on a cosmetic or medical indication. The use of botulinum toxin is also known to have been considered in connection with bioterrorism – either by inhalation or injected into food (4).
Foodborne botulism was most common in the early 1900s, as the use of canning became more common. In Norway today botulism is most frequently seen in connection with fish fermentation and meat curing. Foodborne botulism is now a rarity in Norway, with 39 reported cases in the period 1977–2016 (5). During the same period there was one death.
Prodromal symptoms of foodborne botulism are nausea, vomiting, abdominal pain, diarrhoea, dry mouth and sore throat. Our patient had most of these symptoms at the time of admission, but they are nonspecific, and may have a number of causes.
The neurological symptoms developed by degrees: ptosis, double vision, slurred speech, symmetrical paralysis, urine retention and obstipation. Patients are not normally febrile, and the cerebrospinal fluid is expected to be normal. Sensory effects other than blurred vision are not normal. Symptoms of autonomic instability, with gastrointestinal dysfunction, changes in resting pulse, loss of response to hypotension and change of position, hypothermia and urine retention may occur. Prior to diagnosis our patient appeared to have pronouncedly fluctuating blood pressure.
Patience is important in the treatment, as it may take up to 100 days for an improvement to occur (6).
Botulism is treated with a single dose of botulism antitoxin manufactured from the blood of an immunised horse or sheep. According to the infection prevention guide from the Institute of Public Health, the institute is responsible for the supply of antitoxin in Norway. Outside the institute's opening hours, the antitoxin can be ordered from Vitus Pharmacy at Jernbanetorget, Oslo (5). When botulism is suspected, it is important to start treatment rapidly, and not wait for a final diagnosis.
Spores of C. botulinum are very hardy, tolerating heating up to 100oC for at least four hours. Under suitable conditions, the spores germinate into toxin-producing bacteria. A temperature of 25–37oC is ideal for growth, but some types can grow at temperatures from 4oC. In foodborne botulism, the toxin is already in the food that is consumed, and the incubation period is therefore shorter than, for example, wound botulism. It is normally 12–36 hours, but may vary from hours to up to a week (6).
Our patient found much of his food in waste containers. Looking for food that is still edible in the waste containers of food shops has become more and more popular – a reaction to the discarding of extensive quantities of still edible food. The phenomenon is called "dumpster diving". Those who engage in the practice believe that seeing, smelling and tasting the food can determine whether it is spoilt. This is not always the case when it comes to botulinum toxin, because some types of toxin do not change the odour, taste or appearance of food. It gradually emerged that our patient not only found his food in containers, but that he also stored it for long periods, sometimes without adequate refrigeration.
The municipal infection prevention doctor must be contacted immediately on suspicion of botulism, so that infection tracing can begin. In addition to inspecting food, household waste should be examined, and this possibility may be lost if there are delays.
Botulism diagnostics takes time. This is undesirable for the individual patient, who may have to be treated for possible differential diagnoses while waiting for a final answer, with the risk of side effects. While waiting for results from the mouse bioassay, our patient was treated with immunoglobulin, as Guillain-Barré syndrome could not be excluded. Waiting for a diagnosis also means that extensive infection tracing work must be initiated before a final diagnosis can be made.
If foodborne botulism is suspected, serum from the patient must be sent to the Institute for Food Safety and Infection Biology in Oslo. In our experience, it may take time, for various reasons, from the dispatch of the sample until an answer is received. Knowledge of the toxin type facilitates the work of tracing the infection, but it is not possible to have the toxin type determined in Norway. Sample material can be sent to the State Serum Institute (SSI) in Copenhagen, as is the case for wound botulism.
Botulism is a rare condition, and inadequate knowledge of it may delay diagnosis and at worst be fatal. We have had three cases of foodborne botulism at our hospital in the course of eight months. All were confirmed by tests on mice.
No infection connection has been found between the cases, but the work of tracing the infection was difficult because of delays. All three patients had to have respirator treatment, and two suffered respiratory failure before being intubated. Respiratory failure is the main cause of death in connection with botulism.
The patient described in this article was the first of the three, and his respiratory failure was initially found inexplicable. He had already suffered respiratory and circulatory failure before the diagnosis was suspected. Owing to close follow-up from the ward nurse, a doctor was present when the failure occurred, with the result that appropriate action could quickly be taken.
Patients with inexplicable respiratory failure should be closely monitored. We suspect that botulism is an under-diagnosed condition.