Describe the factors that influence the epidemiology of clostridial diseases of livestock.

QUESTION: Using examples, describe the factors that influence the epidemiology of clostridial diseases of livestock. What steps can be taken by farmers in preventing and controlling the diseases?

Clostridia diseases are fatal diseases that strike livestock suddenly like black leg, botulism, malignant oedema and tetanus. The main source of clostridia is spores in soil and regional differences in husbandry practices can affect incidence of disease. The factors that influence disease occurrence depend on the species of clostridia involved. They may be ingested with feed and water and consequently healthy robust animals are often the first victims. The organisms are often present in organs or tissues of healthy animals and become pathogenic only after primary factors cause changes in habitat. Examples of such primary factors include accidental injury, husbandry procedures, fighting, liver fluke infestation, overeating (too much starch).

Factor that influence the epidemiology of clostridia diseases is that toxins may be ingested after multiplication of the clostridia bacteria in the environment and for example black leg is most commonly caused by C chauvoei and C feresi. These can produce environmentally persistent spores when conditions are not ideal for growth and these spores can remain in the soil for many years in an active state and returned to their infections form when consumed by grazing livestock. Contaminated pasture is a predominant source of these organism, which are also found naturally in the intestines of animals.

Injury or invasive procedures like dehorning, castration causes diseases like tetanus. The organism C tetani is found in soil and manure, when it is taken in by infecting a deep wound or orally, it can proliferate and produces a potent toxins affecting the nervous system. Malignant oedema is an acute, rapidly wound infection in grazing animals which is caused by toxins produced by several types of clostridia organisms e.g. C septian and C perfringes generally they live in the soil but can contaminate wounds also for example when following shearing, castration, tail docking and fight wounds in rams.

Botulism in cattle is also caused by toxins produced by Clostridium botulism and mostly common found in water, soil and also a normal inhabitant of the intestinal tract of cattle and poultry. The bacteria produces long live spores which ensure survival I the environment. Spores germinate in the moist, low oxygen environment such as rotting carcass or decaying organic materials and under favorable conditions proliferate and produce botulinum toxin leading to intoxication if consumed.

There are several steps that can be taken by a farmer in preventing and controlling the diseases like botulism, a famer must burn the upper layer of soil to eradicate left overs spores is the best way to stop black leg from diseased cattle and diseased cattle should be isolated when an animal has died as a result of the blackleg disease. They should bury the carcass or bury it deeply with time, burn any contaminated materials including feaces, disinfect any contaminated are and do not feed the carcass to any other animals. Farmers should avoid problems with chicken litter on pastures as chicken litter has been proven many times to be a potent source of botulism toxin, where chicken litter is used as fertilizer, it should be only used in situation where it can be incorporated into the soil immediately after being spread such as when pastures are being renovated. Farmers should not allow access of cattle to piles of stored chicken litter because they will eat it. Farmers should ensure that feedstuffs are not contaminated with botulinum toxin is part of quality assurance system they can implement to prevent botulism. Farmers should address nutritional deficiencies, in there grasslands area, the correction of any dietary deficiencies all help to prevent bone chewing by cattle and it should be accompanied by an appropriate vaccination programmes. Vaccination is the only long term prevention strategy for botulism with bivalent botulinum vaccines and vaccines require boosters to be given to maintain protective levels of immunity

In preventing malignant edema, farmers in endemic areas, their animals should be vaccinated before they are castrated, dehorned, or docked. Calves should be vaccinated at 2 months of age. Two doses 2–3 week apart generally give protection. In high-risk areas, annual vaccination is indicated, as is revaccination after severe trauma. Treatment with high doses of penicillin, tetracyclines, or broad-spectrum antibiotics is indicated early in the disease. Although injection of penicillin directly into the periphery of the lesion may minimize spread of the lesion, the affected tissues usually slough.

Animals should be vaccinated against tetanus using a tetanus toxoid to induce active immunity. Formalin-inactivated, adjuvant toxoids are readily available and often combined with other vaccines. They appear to be very safe and induce a long-lasting immunity. All humans working with animals should ensure that their vaccination status for tetanus is good and proper immunization and wound management should prevent tetanus.

Farmers should ensure diet changes, and animals should not overeat because overeating and acidosis resulting in clostridia bacteria in the gut multiplying and causing disease

References

Clostridia diseases: Blackleg. The Merck Veterinary Manual. Available from http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/50704.htm Retrieved 2012-03-20.
Mackintosh C, Haigh JC, Griffin F. Bacterial diseases of farmed deer and bison. Rev Sci Tech. 2002 (2):249-63
Tetanus. In: Epidemiology and Prevention of Vaccine-Preventable Diseases - The Pink Book. 7th ed. Waldorf, Maryland, USA: Public Health Foundation, Centers for Disease Control and Prevention, 2003: 49-57. http://www.cdc.gov/nip/publications/pink/tetanus.pdf
https://www.zoetis.co.uk/conditions/dairy/clostridial-diseases.aspx