Tetanus

Overview

Tetanus is an infection caused by bacteria Clostridium tetani (C. tetani), that are found in the environment. Tetanus is an uncommon but very serious disease that requires immediate treatment in a hospital.

Disease epidemiology

C. tetani spores are ubiquitous in the soil. They are also found in the gut of some livestock and pets. Infection occurs worldwide and is more common in agricultural areas where there is likely to be more contact with animal faeces. It is relatively rare in Singapore and in other developed countries where immunisation programmes are well-established.

Pathogen(s)

Clostridium tetani

Transmission

Transmission occurs when spores of C. tetani, which may be found in the gut of mammals and the environment (soil, dust or manure), enter the body through breaks in the skin, such as cuts or puncture wounds caused by contaminated objects.

Incubation period: Typically 3 to 21 days; range is 1 day to several months.

Infectious period: There is no person-to-person transmission.

Clinical features 

An exotoxin produced by C. tetani at the site of an injury affects the motor system and less commonly, the autonomic and sensory system. It causes hyperactivity of voluntary muscles in the form of rigidity and spasms, autonomic dysfunction (irritability, restlessness, sweating, tachycardia, labile blood pressure) and altered sensation (pain and allodynia). Patients do not have impairment of consciousness or awareness. There are 4 distinct clinical patterns:

1.  Generalised tetanus: the most common and severe form of tetanus affecting muscles of the whole body. The classical findings are:

   1. Risus sardonicus (sardonic smile resulting from sustained spasm of facial muscles)

   2. Opisthotonus (the backward arching of the column due to rigidity of the extensor muscles of the neck and back)

   3. Board-like rigid abdomen which may mimic an acute abdomen

   4. Respiratory failure and dysphagia due to rigidity and spasms of the laryngeal and respiratory muscles

   5. Positive spatula test – a clinical test that involves touching the posterior pharyngeal wall with a soft tipped instrument. A positive result is the reflex spasm of masseters causing a “bite down” action versus a negative result of a gag reflex (with attempted expulsion of the instrument)

2. Local tetanus: Only affecting one extremity or body region but may progress to generalised tetanus.

3. Cephalic tetanus: A localised form of tetanus only involving cranial nerves e.g. dysphagia, trismus, focal craniopathies. The facial nerve is most commonly affected.

4. Neonatal tetanus: Generalised form of tetanus occurring in children aged below 1 month. This most commonly occurs 5 to 7 days following birth, often as a result of non-sterile handling of the neonatal umbilical stump. Features are similar to those of generalised tetanus, but the disease progresses more rapidly than in older individuals.

Risk factors

Risk factors include:

• Unvaccinated status

• Outdated tetanus booster shots

• Age above 65 years

• Comorbidities (e.g. diabetes mellitus)

• Immunocompromised or immunosuppressed state

• Intravenous drugs use

Diagnosis 

The diagnosis of tetanus is made based on history, clinical findings and immunisation history. Laboratory tests are generally not helpful in the diagnosis of tetanus.

Treatment and management

There should be adequate wound cleaning and debridement of any inoculating injury. Antitoxins should be given to neutralise unbound toxin.  

All patients with active tetanus should be vaccinated. Antibiotics are universally recommended.

Supportive measures are provided, including medications for control of muscle spasms, autonomic lability, and endotracheal intubation for airway support.

Precaution, prevention, and control 

Standard precautions apply in healthcare settings. 

Post-Exposure Prophylaxis: If a person sustains a tetanus-prone wound (e.g. contaminated with dirt, faeces, soil and saliva, puncture wounds, avulsions, and wounds resulting from crushing, burns, and frostbite) and has unknown vaccination status or has not completed the primary vaccination series, they should receive antitoxins as well as the Tetanus toxoid vaccination. 

Vaccination remains the main preventive measure. Tetanus vaccination is part of both the National Childhood Immunisation Schedule (DTaP at 2 months, 4 months, 6 months and 18 months, and Tdap booster at 10 to 11 years). 

The National Adult Immunisation Schedule recommends vaccination for pregnant women (a dose of Tdap between 16 and 32 weeks of every pregnancy). Adults should receive a Td booster every 10 years.

Notification

Tetanus is a notifiable disease under the Infectious Diseases Act.

Who should notify:

• Medical practitioners

When to notify:

• On clinical suspicion

How to notify:

• Please refer to the Infectious Disease Notification for more information. 

Notification timeline:

• Within 72 hours

Resources

Please refer to the Weekly Infectious Diseases Bulletin for the number of confirmed tetanus cases in Singapore.

For more information on tetanus, please refer to the World Health Organization and Centres for Disease Control and Prevention website.

For general travel advisory, please refer to Health Advisory for Travellers.