Exercise 30. Test yourself by answering these questions to see how much you remember and understand.

1. What is the main source of infection in case of blackleg?

2. What animals are susceptible to blackleg?

3. How does bacterium enter the body?

4. What body parts are most commonly affected?

5. What is the main danger in case of blackleg?

6. How can the onset of blackleg be characterized?

7. Does treatment of blackleg early stages make sense?

8. How can blackleg be prevented?

TEXT E

TETANUS

VOCABULARY LIST TO TEXT E

Tetanus is a bacterial life-threatening diseasethat can affect all domestic animals and humans worldwide. It is caused by the bacterium Clostridium tetanii, which can be found in soil, dust and manure andwhich survives in the environment for a long time. The bacteria enter animals either through deep penetrating or puncture wounds, during parturition, or as a consequence of such procedures as castration, dehorning or tail-docking.The disease is seen in animals of all ages. It does not spread from animal to animal but sometimes a number of animals may develop tetanus at the same time. This is usually because the animals have become infected at the same time following a procedure such as castration.Horses are particularly susceptible to the diseasebecause of their tendency to incur injuries.

The time between infection and disease can be very short (two or three days) or quite long (four weeks or more), depending on how long it takes for contaminated area to develop a low level of oxygen.The tetanus organism must enter the wound and be “sealed off” from the air before it can multiply. These bacteria do not need oxygen (they are classified as ‘anaerobic’ bacteria) and multiply rapidly in the damaged tissues in the absence of oxygen. They produce a toxin (tetanus toxin), and it is this toxin that causes the classical signs of tetanus.Tetanus toxin attacks nerves controlling the muscles of the body. This causes progressively worsening muscular stiffness and spasm.The animal will not be able to swallow and have an unsteady gait. Eventually, the animal falls in a tetanic spasm with the limbs stretched out rigidly and is unable to breathe. The affected horse, for example, will become stiff and have difficulty moving and eating. The tail is often held out straight and the horse develops an anxious expression because of facial muscle spasm. Any stimulus such as loud sound, bright light or touch can exacerbate the clinical signs. The horse may sweat. In advanced cases, the horse will collapse with spasms, convulsions and death from respiratory failure. The “tetanic” muscle spasms are usually characteristic enough to diagnose tetanus especially if there is a history of a deep wound in the last few weeks.

Tetanus is easy to prevent but difficult to treat.It can be easily prevented through effective vaccination programs,which are available for horses, cattle, sheep and goats.However, if signs are detected very early and the disease is not too severe, treatment can be successful using therapeutics such as antitoxin and antibiotics. The injection of a relatively small dose of antitoxin, such as the minimum dose recommended for prevention, if given within a few hours of the injury, should provide effective protection over the danger period. Treatment of clinical cases can be costly and may not always be successful and, unfortunately, in most instances the animals are often found dead.Sadly, infected horses and ponies usually die or require euthanasia.

People cannot get tetanus from direct contact with cattle, but are susceptible to infection through penetrating wounds or cuts. It is very important for all people who handle livestock to make sure that their tetanus vaccinations are up to date.

EXERCISES TO THE TEXT

Exercise 31.Look through the text and find information about:

- causative agent of tetanus;

- parts of the world where tetanus is common;

- age of the animals that can contract tetanus;

- procedures predisposing for tetanus;

- the way bacteria enter the body and multiply there;

- clinical signs of tetanus;

- stimuli that can exacerbate tetanus clinical signs;

- treatment and prevention of tetanus.