Lockjaw - Causes of tetanus

Tetanus is caused by the Clostridium tetani bacterium.

Clostridium tetani spores can live for a long time outside the body and are widespread in the environment. They are commonly found in the manure of animals such as horses and cows, and in contaminated soil.

After they enter the body, the tetanus bacteria quickly multiply and release tetanospasmin, a type of poison known as a neurotoxin. Tetanospasmin can slowly travel through nerves, until it reaches the spinal cord or brainstem.

The neurotoxin blocks the control of the nerve cells in the spinal cord and brainstem that control the muscles, causing them to be overactive. This leads to the muscle spasm and muscle stiffness associated with tetanus.

Cuts and wounds

One of the most common ways the tetanus bacteria enter the body is through a cut or a puncture wound. Even minor puncture wounds, such as piercing your skin with the thorn of a rose, could allow the bacteria to enter your body.

Tetanus bacteria thrive and breed in places where there is little or no oxygen. This is why the infection often occurs in deep cuts and wounds. To help prevent a tetanus infection developing, always ensure that cuts and wounds are thoroughly cleaned.

Other entry points

As well as entering the body through cuts and wounds, the tetanus bacteria can also enter through:

• lacerations – tears or splits in the skin caused by blunt trauma such as a blow to the skin, or a sharp object such as a knife or broken glass
• abrasions – wounds caused by friction damage, such as the type of wound you would get after falling off a bike and scraping your knee
• burns 
• animal bites 
• body piercings and tattoos (if unsterilised equipments is used)
• eye injuries

Risk groups

Some groups of people, such as travellers and people who inject drugs, may be at increased risk of developing tetanus.

Travellers

If you are travelling abroad, make sure your vaccinations are up to date, according to the UK schedule. Depending on where you are travelling, you may need additional doses of certain vaccinations.

Read more about travel vaccinations.

If you are travelling to a remote area where medical services may not be easily accessible, and you had your last tetanus vaccine more than 10 years ago, you need to have a booster dose (even if you have already had the full five doses). This is done as a precaution, in case you get a wound that is vulnerable to a tetanus infection and medical care isn't available.

Read more about the tetanus vaccine.

Injecting drug users

People who inject illegal drugs such as heroin or methamphetamine have an increased risk of developing tetanus. Drug dealers often mix these types of drugs with a chemical called quinine. Quinine can be contaminated by the tetanus bacteria.