The first observations of an all-too-common disease plaguing South African farmers were made, not by scientists or veterinarians, but by travelers and evangelists journeying through the dry, hot, and dusty North-Western parts of South Africa in the 1880s. Their keen observation and deduction skills caused the government of that time to employ experts to further investigate this disease, which was rampant in many communities and caused major cattle losses. They discovered that this disease, locally referred to as “lamsiekte”, was caused by some sort of malnutrition, however, whether this was a result of some form of toxic plant ingestion or due to an infectious agent was not yet known, and quite heavily debated. 

 

Nonetheless, further investigations into this disease were made, and feeding experiments on some of the local cattle were done on a farm called “Armoedsvlakte” around 1914. Sadly, the outbreak of the First World War greatly impeded the progress made in discovering the causes of this ailment, and only 5 years later the help of chemists and botanists were employed to continue exploring the disease they would later call “botulism”. 

 

Mere days after being posted at Armoedsvlakte, Arnold Theiler – known as the father of veterinary medicine in South Africa – conceived his theory and recorded it as follows:

“Soil and vegetation deficient in phosphorus (remediable with phosphatic manuring) produced pica or osteophagia in cattle compelling them to find phosphorous in putrid bones and carcass material (remediable by feeding bone meal and other phosphor-rich material). The position in carrion of all sorts (dead meerkats, spring hares, ostriches, tortoises, household refuse, etc.)—a toxigenic saprophyte (later identified as the cause of a form of botulism) could be eliminated by clearing pasturage of all such material”

 

 

Based on his theory, solutions were developed around feeding adaptations as a means of prevention, particularly adding sources of phosphate, such as bone meal, to the diets of grazing cattle. Later research at Onderstepoort ultimately confirmed and established the relationship between the consumption of carcass material and intoxication by the Clostridium botulinum exotoxin. This bacterium was first isolated by P.J. du Toit and E.M. Robinson in 1928 and finally identified as Clostridium botulinum in 1930, after which the development and refinement of an effective botulism vaccine was made possible.

 

Botulism is a rapid-onset disease that affects humans, warm-blooded animals, birds, and also some species of fish. Despite being caused by bacteria, those affected are considered “intoxicated” rather than “infected”, as the physical effects are due to the extremely potent neurotoxins produced by this spore-forming bacterium, rather than the bacteria themselves. These toxins are found in decomposing plant and animal material that contain the Clostridium botulinum bacteria, and exposure occurs when ingestion of contaminated materials takes place. This bacteria also naturally occurs in the digestive tract of healthy cattle, horses, and poultry, however, the environment is not favorable for spore germination, meaning it is of little to no risk of intoxication to the animal.

 

Due to it not being an infectious disease, sick animals pose no threat of cross-infection to healthy animals. This neuroparalytic disease is characterized by the partial or complete paralysis of the voluntary motoric muscles - as well as those involved in chewing and swallowing - and can oftentimes be fatal. The first signs of botulism intoxication are usually weakness in the hindlimbs, which gradually progresses to paralysis, respiratory paralysis, collapse, and eventually death. Paralysis can occur anywhere between 2 to 6 days from the time of ingestion, with animals normally not surviving two days after they collapse.

 

Clostridium botulinum can produce seven types of this neurotoxin - types A, B, C1, D, E, F, and G. Types A, B, and E are responsible for human intoxication, whilst type C1 greatly affects chickens, ducks, horses, and cattle, who are more so affected by type D. In South Africa, toxins from Clostridium botulinum bacteria types C and D are normally the most important as these are among the deadliest and are not deactivated by the digestive process. However, they are temperature-sensitive and can be deactivated by exposing them to temperatures of 80°C or greater for at least 10 minutes.

 

The neurotoxins produced by Clostridium botulinum are usually found in animal carcasses, rotting plant material, poorly prepared silage, and sometimes in contaminated water and soil. Autointoxication – a condition where the naturally occurring botulism bacteria cause intoxication to its host - can also occur. This, however, occurs very rarely and usually only in cases where other conditions such as gastric ulcers, liver necrosis, abscesses in the umbilical cord and lungs, lesions in the skin and muscles, and necrotic lesions in the digestive tract are prevalent.

 

The combination of extensive farming practices, phosphorus-deficient soils, and the prevalence of Clostridium botulinum Type D makes South Africa an ideal location for high botulism incidence. Cattle deficient in phosphorus tend to seek out and chew on fragments of bone they come across while grazing in the veld. If these bones originated from a carcass carrying Clostridium botulinum Type D, that animal will likely be intoxicated. Along with the neurotoxins, the cattle chewing on affected bones will also take in spores. These spores then develop in the intestinal tract and, once the host animal dies, infiltrate the muscular tissue. Consequently, this muscular tissue may infect other animals, continuing the toxic cycle.

 

 

The best protection method against botulism outbreaks is prevention; active immunization of cattle in high-risk herds has proven to be very effective in South Africa if done annually.

 

Although no formal treatment for botulism in cattle exists, an antiserum exists which may be effective if given in the early stages of intoxication. The antiserum is mainly used as a prophylactic measure in cattle herds where recent botulism outbreaks have occurred. Supportive treatment of sick animals is often the only available option, which includes hydration, correcting any electrolyte disturbances, and implementing general supportive measures. Intravenous fluid therapy is usually recommended.

 

The best protection method against botulism outbreaks is prevention; active immunization of cattle in high-risk herds has proven to be very effective in South Africa if done annually. It is furthermore also crucial that cattle not be given contaminated feed or water, and that management practices allow for the removal of carcass material in grazing camps. Finally, dietary phosphorus deficiencies should be addressed by providing a phosphate lick throughout the year as large areas of South Africa have phosphate deficient soils.

 

From the initial observations and early studies of this ever-looming disease, our journey toward comprehending its intricate nature and mechanisms has been marked by significant progress. While botulism remains a significant concern within South Africa's cattle industry – posing substantial risks to the health and lives of cattle and, consequently, financial losses for farmers – it is one problem that need not cause dread. By implementing effective management strategies and taking proactive preventive measures, every cattle farmer can safeguard their herd and ensure the continued success of their farming operations, confidently and prosperously farming for the future!

 

 

 

 

---