ZIMSEC O Level Combined Science Notes: Animal Parasites and diseases
- Farmers in Zimbabwe typically raise goats, cattle, chickens and sheep.
- Disease spread much more quickly where large numbers of the same type of livestock are kept close together when compared to the wild.
- Livestock diseases are caused by pathogens.
- These organisms live on or in the host animal.
- Pathogens include parasites and microorganisms e.g. bacteria and viruses.
- Pathogens destroy tissues of the host animal and use it for food.
- This results in reduced productivity, reduced amount and quality of milk and meat.
- Infected female animals may become infertile.
- Some pathogens also produce toxins which cause diseases and results in the host animal becoming sick.
- Some diseases are spread by .
- Vector-a carrier of diseases and infection. For example a mosquito is a vector that carries and transfers the infectious agent.
- Parasite-an organism which lives in or on another organism (its host) and benefits by deriving nutrients (food) at the host’s expense.
- Parasites do not always cause diseases but still result in reduced productivity in the host animal.
- Parasites such as fleas, ticks and lice live outside the host.
- Parasites like worms and liver flukes may live inside the host.
- Tapeworms live inside the intestine and uses up the host’s food leaving the host thin and weak.
- Flukes are small flatworms that infect the host’s liver.
- They can be controlled by dosing the whole herd even those that appear unaffected.
- The risk of fluke infection can also be reduced by rotational grazing.
- Infected animals should be quarantined (kept separate) to prevent diseases from spreading.
- The movement of animals should be controlled to prevent them from being infected especially in rural areas where herds may come into contact with infected herds.
- Ticks cause a number of diseases in cattle e.g. heart water and redwater.
- Ticks are common vectors in cattle although they have been known to affect other animals such as goats.
- Ticks also suck blood weakening the host and resulting in reduced productivity.
- They can be controlled by dipping the livestock.
- The dips have a chemical that will kill the ticks.
- They can also be controlled by tick birds.
|Foot and mouth |
(Cattle and Goats)
|virus||Fever, excessive saliva production, loss of weight, reduced milk production, mouth blisters, possible death, loss of appetite and dullness.||There is no specific cure for the disease as surviving animals usually recover after 7-10 days. Take preventative action such as vaccinating, kill diseases animals or keep them in quarantine. Notify the responsible authorities.|
(In cattle and goats)
|bacterium||Fever, loss of appetite, watery faeces with traces of blood, blood in noses and mouth of the dead animals, blown up stomachs, death usually occurs in 24 hours.||Can be treated with antibiotics. Burn or Bury dead animals.
Notify the responsible authorities.
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