Specific Disease Studies

Tetanus

Contributors

Ben Whitten

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What is tetanus?
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Tetanus is caused by the exotoxin secreted by the bacterium Clostridium tetani.


Spores of tetanus bacteria are found everywhere in the environment, including soil, dust, and manure. The spores develop into bacteria when they enter the body.

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How is tetanus transmitted?
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The spores can get into the body through broken skin, usually through injuries from contaminated objects. Tetanus bacteria are more likely to infect certain breaks in the skin, including:

  • Wounds contaminated with dirt, faecal matter or spit

  • Wounds caused by an object puncturing the skin

  • Burns to the skin

  • Crush injuries

  • Injuries with dead tissue

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What is the typical pathology (signs, symptoms, progress) of tetanus?

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Tetanus is often called “lockjaw” as one of the common signs of the infection is tightening of the jaw muscles. Other symptoms of tetanus include:


  • Sudden, involuntary muscle tightening (spasms) often in the stomach

  • Painful muscle stiffness all over the body

  • Trouble swallowing

  • Jerking or staring (seizures)

  • Headache

  • Fever and sweating

  • Changes in blood pressure and heart rate


There are also numerous possible complications of tetanus.


  • Uncontrolled/involuntary tightening of the vocal cords (laryngospasm)

  • Broken bones (fractures)

  • Infections gotten by a patient during a hospital visit

  • Pulmonary embolism

  • Aspiration pneumonia

  • Breathing difficulty, possibly leading to death

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What is the life cycle of tetanus?
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There are two primary life stages in the Clostridium tetani bacteria, being sporular and vegetative. The sporular form can withstand oxygen and environmental extremes, while the vegetative stage is extremely anaerobic and are unable to survive oxygen exposure.


The life cycle of tetanus can be divided into 5 categories.

  1. Soil reservoir: Soil particles containing bacterial spores can be found on things such as rusty nails and dog's teeth

  2. Mode of transmission: Portal of entry is through a deep wound in the skin which involves direct contact with the soil reservoir (nail or dog for example)

  3. Reproduction: Inside the deep, hypoxic wound, bacterial spores germinate, grow and multiply asexually via binary fission

  4. Production of toxin: During the growth of the bacteria, particular neurotoxins are produced which travel inside neurons from the peripheral nervous system to inhibitory interneurons in the central nervous system

  5. Host impact: The toxin blocks inhibitory neurotransmitters, which means that nerve impulses fire continuously and produce rigidity, unopposed muscle contraction/spasm including lockjaw - tetanus is infectious, but not contagious

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What is the pathogenicity of tetanus?
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The spore-producing bacteria can enter the bloodstream via a wound to the skin and germinate in the ideal anaerobic conditions of a deep wound. The spores then produce two toxins known as tetanolysin and tetanospasmin. Tetanolysin is a hemolysin and does not have any known pathological activity to date. Tetanospasmin, on the other hand, is a potent toxin that enters into the nervous system and has several effects that lead to the symptoms of the disease known as tetanus.

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Where is tetanus prevalent geographically?
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Today the majority of new cases of tetanus occur in South Asia and Sub-Saharan Africa. These two regions account for 82% of all tetanus cases globally.


The risk of death from tetanus is highest among people who are 65 years or older. Other risk factors for tetanus are diabetes, a history of immunosuppression, and intravenous drug use. Those who are not immunised for tetanus are also at high risk.

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What are the treatments/prevention/control for tetanus?
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There is no cure for tetanus – a tetanus infection requires emergency and long-term supportive care while the disease runs its course. Treatment consists of wound care, medications such as antitoxin therapy, sedatives and antibiotics to ease symptoms and supportive care in an ICU. The disease progresses for about two weeks and recovery can last about a month.


Immunisation is the only effective prevention of tetanus. Tetanus toxoid is an effective, safe, stable and inexpensive vaccine that can be given to all ages, to pregnant women and to immunocompromised individuals.

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