Overview

• caused by Clostridium tetani
• Organism lives in soil as well as the stool of domestic animals and people
• Incubation Period: 3 to 21 days (10 days on average)
• Earlier onset after exposure is associated with more aggressive infection and worse prognosis
• Tetanus duration is 6-8 weeks (to allow nerve regrowth)
• Expect a long, slow recovery if survived
• Tetanus spores enter patient via wounds (even minor, superficial wounds, umbilical stump of newborn) 🡪
  • 🡪 Spores germinate 
  • 🡪 Germinated spores produce Tetanus toxin (exotoxin) 
  • 🡪 Tetanus toxin spreads to nerves either hematogenous or retrograde transmission via nerves
  • 🡪 Toxin irreversibly binds nerves
  • 🡪 Blocks presynaptic release of inhibitory Neurotransmitters (Glycine, GABA)
• Risk Factors
  • Contaminated wounds or Puncture Wounds (e.g. open Fractures, ocular injuries)
    • However up to 30% of Tetanus cases occur in clean wounds (e.g. surgical wounds)
  • Inadequate tetanus Vaccination (or large pathogen burden)
  • Advanced age (waning Immunity)
  • HIV Infection
  • Diabetes Mellitus
  • Corticosteroids or other Immunosuppressants

Etiology

1. Clostridium tetani: a gram-positive, spore-forming, obligate anaerobic bacillus.
2. Common in hot, wet climates with rich organic soil.
3. Entry through minor wounds, often unnoticed

Epidemiology

• Worldwide incidence reduced due to vaccination campaigns.
• Still prevalent in low-resource settings with higher mortality rates.
• in Australia:
  • Fewer than 20 cases reported annually, mainly in older adults.
  • Case-Fatality Rate: Approximately 2%.
  • Common Causes: Minor penetrating injuries from gardening, often not medically attended.

Clinical Details

• Muscle spasms are initially intermittent, each lasting seconds to minutes
  • With progression, spasms increase in frequency and duration
  • Spasms may be triggered by even minor stimuli (light touch)
• Opisthotonos (arched back)  
• Lockjaw (Trismus)
  • Painful, contractions of the masseter and neck Muscles
• Facial Muscle spasms
• Abdominal rigidity (older children and adults)
• Muscle spasm
  • Oropharyngeal Muscle spasm (Dysphagia)
  • Neck Muscle spasm (Torticollis)
  • Laryngeal Muscle spasm (airway compromise)
  • Respiratory Muscle spasm (apnea)
• Autonomic instability
  • Fever, Irritability, Sweating, Tachycardia
  • Labile Blood Pressure including Hypertension
  • DysArhythmia

Types of Tetanus:

• Neonatal Tetanus (accounts for 50% of worldwide deaths): Associated with contamination of the neonatal umbilical stump
  • Presents in the first week of life with poor feeding, decreased movement, irritability, Muscle rigidity and spasms
• Localized Tetanus to one body region (rare)
  • Typically progresses to Generalized Tetanus, Lower mortality if Tetanus remains localized
• Cephalic Tetanus
  • Localized Tetanus from a head, ears, nose or neck wound
  • Often progresses to generalized Tetanus
• Generalized Tetanus (80% of cases)
  • Associated with rigidity, spasm and Autonomic Dysfunction
  • Onset at 3 to 21 days after infection
  • Cephalocaudal spread of Muscle spasms
  • Lockjaw
  • Opisthotonos
  • Death due to diaphragmatic spasm or laryngospasm

Treatment and Management

• Tetanus Immunoglobulin (HTIG): Neutralizes unbound toxin.
• Antibiotics:
  • Metronidazole preferred
  • penicillin historically used but found potentially harmful in combination with tetanospasmin.
• Wound Debridement: Wound Debridement and removal of necrotic tissue
• Neuromuscular Blockade: Manage muscle rigidity and spasms.(sedation, Analgesics and Muscle relaxants)
• Supportive Care:
  • Ensure adequate airway (Advanced Airway)
  • management of autonomic instability

Prognosis

• Depends on the time between symptom onset and first spasms.
• Severity linked with shorter incubation periods.
• Mortality is reduced to as low as 15% in developed countries with Intensive Care
• Adult Mortality: 52%
• Neonatal mortality: 88%’
• Mortality Rate and Factors:
  • Age and general health of the patient.
  • Access to intensive care and ventilatory support.
  • Early administration of tetanus immunoglobulin and appropriate antibiotics.
  • Severity of symptoms at presentation.
  • Neonatal Tetanus: Particularly high mortality rate, prevention through maternal vaccination.

Complications of Tetanus

• Respiratory Failure: Due to spasms of respiratory muscles.
• Autonomic Dysfunction: Manifests as labile blood pressure, arrhythmias, cardiac arrest.
• Fractures: Caused by severe muscle contractions.
• Neuropsychiatric Complications: Long-term motor and cognitive issues in survivors.
• Secondary Infections: Such as aspiration pneumonia, urinary tract infections.
• Muscle Contractures and Joint Dislocations: Resulting from prolonged spasms.

Prognosis Based on Symptom Onset and Spasms

• Short Incubation Period: More severe symptoms, poorer prognosis.
• Longer Incubation Period: Generally milder disease and better prognosis.

Prevention

• Vaccination: Key preventive measure, especially in childhood. adults should receive a booster vaccine every ten years
• Wound Care: Proper care and cleaning of wounds.
• Education: Awareness about tetanus symptoms and the importance of timely medical intervention.

Consultations and Interprofessional Care:

• Involves an intensivist, infectious disease specialist, neurologist, pulmonologist, anesthesiologist.
• Critical for managing severe cases and complications.

Deterrence and Patient Education:

• Emphasize the importance of immunization.
• Educate about aseptic techniques in birth and first aid for wounds.

Tetanus Prophylaxis in Routine Wound Management

History of tetanus vaccination	Time since last dose	Type of wound	DTPa, DTPa, dT,	Tetanus immunoglobulin
≥3 doses	<5 years	Clean, minor wounds	No	No
≥3 doses	<5 years	All other wounds	No	No (unless person has immunodeficiency)
≥3 doses	5–10 years	Clean, minor wounds	No	No
≥3 doses	5–10 years	All other wounds	Yes	No (unless person has immunodeficiency)
≥3 doses	>10 years	Clean, minor wounds	Yes	No
≥3 doses	>10 years	All other wounds	Yes	No (unless person has immunodeficiency)
<3 doses or uncertain	Uncertain	Clean, minor wounds	Yes	No
<3 doses or uncertain	Uncertain	All other wounds	Yes	Yes
Give tetanus immunoglobulin to people with a humoral immune deficiency and people with HIV (regardless of CD4+ count) if they have a tetanus-prone injury. This is regardless of the time since their last dose of tetanus-containing vaccine.People who have no documented history of a complete primary vaccination course (3 doses) with a tetanus-containing vaccine should receive all missing doses and must receive tetanus immunoglobulin for tetanus-prone wounds.

Vaccination History Check: Determine if the patient has had a full primary course of tetanus vaccination (3 doses).

1. Clean and Minor Wounds:
   • Fully Vaccinated (3 or more doses): No booster if the last dose was within the last 10 years.
   • Less than 3 doses or Unknown Status: Administer a tetanus vaccine.
2. All Other Wounds (Dirty, Severe, etc.):
   • Fully Vaccinated (3 or more doses): Administer a tetanus booster if the last dose was more than 5 years ago.
   • Less than 3 doses or Unknown Status: Administer a tetanus vaccine. Consider giving tetanus immunoglobulin (TIG) if the patient has received fewer than 3 doses of the vaccine.
3. Considerations for Tetanus Immunoglobulin (TIG):
   • Recommended for
     • severe, dirty wounds
     • unvaccinated
     • incompletely vaccinated
     • vaccination status is unknown
     • severely immunocompromised

Types of Wounds:

• Clean Wounds: Low risk of tetanus, generally superficial with minimal contamination.
• Dirty Wounds: High risk, includes wounds with heavy contamination (soil, feces, saliva), punctures, avulsions, or crush injuries.

Immune Response and Efficacy of Diphtheria and Tetanus Toxoids

• High Immunogenicity: Both diphtheria and tetanus toxoids are highly immunogenic and efficacious.
• Development of Antitoxin Levels:
  • Almost all immunocompetent individuals from infants to adults develop protective antitoxin levels after three primary vaccine doses.
  • Protective levels last throughout childhood.
• Decline in Antitoxin Levels:
  • By middle age, approximately 50% of vaccine recipients have low or undetectable antitoxin levels.
• Anamnestic Response:
  • A single booster dose of tetanus and diphtheria toxoid triggers a rapid anamnestic response in individuals with prior vaccination.

Influence of Maternal Antibodies

• Transplacental Diphtheria Antibody:
  • High levels in infants can reduce the response to the first and second doses of diphtheria toxoid.
  • This effect is typically overcome by the administration of the third dose.
• Tetanus Toxoid Response:
  • The immune response to tetanus toxoid is minimally affected by maternal antitoxin.

Vaccine Efficacy

• Effectiveness:
  • Both vaccines have very high efficacy but are not 100% effective.
  • Immunized individuals who contract the diseases generally experience milder symptoms and reduced fatality rates.
• Protection Threshold:
  • No specific level of circulating diphtheria antitoxin guarantees absolute protection.
  • The minimum protective level is considered to be 0.01 IU/mL.
• Herd Immunity Threshold:
  • To prevent outbreaks, the estimated population immunity threshold is 80–85%.

Booster Recommendations

• Pregnant Women:
  • Offer dTpa between 20 and 32 weeks of gestation during every pregnancy.
  • Protects against pertussis for the woman and newborn and prevents neonatal tetanus.
• Partners of Pregnant Women:
  • Recommended for those whose partners are at least 28 weeks pregnant and haven’t received a pertussis booster in the last 10 years.
• General Adult Population:
  • Adults aged 50 and over should receive a dTpa booster if they haven’t had one in the past 10 years.
  • Adults aged ≥65 years should receive a booster if they haven’t had one in the previous 10 years.
• Travelers:
  • Those going to areas with limited health services should receive a booster if more than 10 years have passed since the last dose.
• Injury-Prone Activities:
  • A booster recommended every 5 years for those engaged in activities like mountaineering, biking, rock climbing, especially in remote areas.

Adverse Events

• Common Reactions:
  • Local reactions and transient systemic symptoms like fever, headache, and malaise post-vaccination.
• Severe Reactions:
  • Rare acute allergic reactions (approximately 1 per million doses).
  • Peripheral neuropathy, particularly brachial plexus neuropathy, may rarely occur.
• Extensive Limb Swelling:
  • Occurs in about 2% of children following DTPa boosters; less common after ADT.
  • Swelling usually resolves without sequelae and does not preclude further doses.

Contraindications and Precautions

• Contraindications:
  • History of severe adverse events associated with the vaccine.
• During Pregnancy and Breastfeeding:
  • Vaccines are safe to use and recommended.
• Immunocompromised Individuals:
  • Safe to administer but may result in a diminished immune response.