BOTULISM is a disease that impacts humans and animals alike; affecting the muscles of locomotion, chewing, swallowing and breathing, ultimately resulting in a progression to flaccid paralysis and respiratory arrest.
A febrile disease, botulism is fatal in most cases.
Toxins are absorbed and transported to sensitive neurons via the blood where they then act at neuromuscular junctions, resulting in motor paralysis without interference in functional sensory function.
Primarily, the toxins affect the peripheral nervous system, where they block the process of synapse release of acetylcholine, which prevents the passage of nerve impulses to the muscles, causing flaccid paralysis.
Botulism usually ends in fatality and vaccination is one of the most effective prophylactic means to prevent this deadly disease, since the neuronal paralysis cannot be reversed by available therapeutic options.
Conventionally, administration of antitoxin was suggested as the first line of management.
Human botulism cases have been treated successfully with antitoxin, mechanical ventilation and other symptomatic therapeutic measures. But, antitoxin treatment in developing countries is still not available.
Botulism can cause a significant economic impact on intensive livestock production systems.
Since the financial loss due to cattle deaths from botulism are a big loss to any farmer, vaccination is an economically viable prophylactic action if performed with adequate sanitary planning.
The use of vaccine protection against botulism can be very effective. However, some factors can minimise this efficiency, such as the amount of ingested dose of the neurotoxin, because even animals that are vaccinated may develop the disease if exposed to large enough amounts of it; or when the source of the toxin is not identified and removed from the area, keeping the animals exposed to the potential for ingesting it.
The occurrence of the disease is mainly related to two factors — the sensitivity of the animal species and amount of botulinum toxin ingested. Indigenous MaShona cattle in Zimbabwe, although susceptible to the disease, are generally less vulnerable.
In humans, symptoms of botulism include double or blurred vision, drooping eyelids, slurred speech, difficulty in breathing or swallowing, dry mouth or muscle weakness that spreads throughout the body.
Botulism antitoxin is used to treat symptoms of botulism in patients exposed to botulinum toxin.
This medicine is to be given only by, or under, the supervision of a doctor
In some covert military operations, botulinum is sometimes used as a bio-warfare agent and is regarded as one of the most potent toxins known to date. Botulinum neurotoxin (BoNT) is deadly and silent and can play havoc in living beings.
Growing, lactating and calfing cattle require more phosphates in their diets than others and are more inclined to develop botulism should their phosphate requirements not be satisfied.
To supplement their dietary intake of phosphates, cattle will be drawn to consume decomposing carcass material.
Stray bone matter from decomposing bird carcasses, tortoises and small mammals such as rats and mice are important sources of the botulism toxin as well as chicken manure, decomposed rock lizards, dead cats and rats, among others .
Should a rat or cat die in a silage bunker, the botulism toxin produced in the carcass can contaminate the silage around it.
Animals eating this silage will contract the disease.
A similar problem can occur when rats die in large bales of hay covered with or wrapped in plastic sheeting.
Carcasses of small mammals and tortoises may remain toxic for as long as 350 days, but usually lose their toxicity after four to six weeks.
The carcass of a small animal containing the toxin can also contaminate drinking water.
Farmers should burn or bury all carcasses, bones or decaying material.
With warmth and sufficient moisture, considerable quantities of toxin can form in a carcass, but under cold and dry conditions, the rate of formation declines dramatically.
Botulism has been recorded where contaminated chicken manure was used as fertiliser on pasture where cattle grazed. Due to its high nitrogen content, chicken litter — matosi ehuku — is often used as a constituent in lick for cattle and sheep.
Autointoxication (self-poisoning), when bacteria normally occurring in the animal produce toxins, is rare.
Conditions promoting this type of botulism include gastric ulcers, liver necrosis, abscesses in the umbilical cord and lungs, lesions in the skin and muscles as well as necrotic lesions in the digestive tract.
Progressive paralysis in an affected animal can vary from less serious to very serious.
Most die if not treated with anti-serum.
Making a diagnosis can be difficult.
What eludes many cattle breeders is that the animal shows no fever. Diagnosis is confirmed by identifying the toxin in a laboratory.
Where a large number of animals have to be tested, the Elisa Test confirms the identity of the toxin.
Tissue samples of botulism can be confused with other diseases and conditions such as milk fever, ketosis, organophosphate poisoning, three-day stiff-sickness, trauma and spinal cord injuries.
Prevention of botulism involves vaccination and good nutrition during winter. In outbreaks of botulism, the immediate removal of the source of the toxin is necessary.
Treatment is only possible in the early stages which requires an antitoxin.
Vaccination can be considered a viable prophylactic, sanitary and economical option.
However, adequate sanitary schedule and planning is necessary for its execution, considering the risks and the time necessary for the cattle to acquire adequate immunological protection.
Sufficient immunity develops two weeks after the supporting dose has been administered.
Where the possibility of botulism in an area is high, a third dose in the immunisation programme should be administered.
Under conditions similar to the present outbreak in Zimbabwe, the best way to contain this disease is to immediately identify and withdraw the feed in which the botulinum toxin is present.
It is important to note that new cases may occur up to 18 days after the removal of contaminated feed.
One of the tenets of sustainable farming and ranching is to treat animals with care and respect, implementing livestock husbandry practices that protect animals’ health and well-being.
By raising livestock on pasture, farmers enable their animals to move freely, engage in instinctive behaviours, consume a natural diet and avoid the stress and illness associated with confinement.
Through careful, responsible management of livestock waste, sustainable farmers also protect humans from exposure to pathogens, toxins and other hazardous pollutants.
Agricultural systems are facing ever-increasing challenges, such as increasing global demand for livestock products involving intensification, conflicting demands on land and water resources as well as climate change.
While in the past Zimbabwe’s cattle herd was predominantly a cultural and socio-economic pursuit, with an overt socio-religious function in society, today’s farmers need to practice early and proactive detection of any livestock inefficiencies and diseases to prevent unnecessary cattle loss.
Practicing advanced and informed cattle husbandry will further bolster the national herd and improve animal welfare in Zimbabwe.
The impact and relationship between sustainable agricultural intensification production models pertaining to cattle welfare, our health and the socio-economic prosperity of our nations is simple but profound.
It is profound because it extends to nurturing all our resources, including livestock and the environment.
Improving our knowledge of cattle husbandry is a step into the light of the future.