Tetanus is an infectious disease caused by contamination of wounds by the bacteria, Clostridium tetani .The term is derived from the ancient Greek words tetanos(taut) and teinein (stretched). Tetanus is a neurological disease characterized by an acute onset of hypertonia, painful muscular contractions (usually of the muscles of the jaw and neck), and generalized muscle spasms without other apparent medical causes.
It is the only vaccine preventable disease that is infectious but not contagious.
Epidemiology
Tetanus causes between 250,000- 300000 deaths worldwide/year. A study from federal medical centre, Asaba ,Delta state, Nigeria over 8 years(Jan 2008- May 2016) to determine the prevalence and case fatality rates of post-neonatal tetanus showed a 0.9% prevalence rate. The male: female ratio was 1.9: 1 and patients’ ages ranged from 2 to 15years. 29% of them had complete immunization during infancy but none had booster doses. Also, 60.9% of them presented with lower limb injuries as the portal of entry. The calculated case fatality rate was 50%.
Etiology
The causative bacterium, Clostridium tetani, is a gram positive bacilli that is anaerobic, and motile. It is a “tough” organism capable of living many years in the soil in spore form. It is found worldwide in soil, in inanimate environment, in animal feces & occasionally human feces. Clostridium tetani produce two toxins ; tetanolysin(which has no relevance in the pathogenesis of tetanus) and tetanospasmin which causes the clinical manifestation of tetanus.
Pathogenesis
Tetanus is not transmitted from person to person, its incubation period is between 3-21days. Infection occurs when C. tetani spores are introduced into acute wounds. The toxin migrates across the synapse, binds to presynaptic nerve terminals and inhibits the release of inhibitory neurotransmitters (glycine and gamma-aminobutyric acid). These neurons become incapable of releasing neurotransmitter.
The neurons, which release the major inhibitory neurotransmitters, (GABA) and glycine, are particularly sensitive to tetanospasmin, leading to failure of inhibition of motor reflex responses to sensory stimulation. This results in generalized contractions of the agonist and antagonist musculature characteristic of a tetanic spasm.
The shortest peripheral nerves are the first to deliver the toxin to the CNS, which leads to the early symptoms of facial distortion and back and neck stiffness. Once the toxin becomes fixed to neurons, it cannot be neutralized with antitoxin. Recovery of nerve function from tetanus toxins requires sprouting of new nerve terminals and formation of new synapses
Clinical forms of tetanus
- Generalized: is characterized by painful generalized rigidity and spasms. The prognosis is often bad.
- Localized: Is an uncommon form . Characterized by rigidity & spasms restricted to muscles around the wound. The prognosis is excellent
- Cephalic: Follows wounds of the face and head. The incubation period is usually short and affected muscles are weak or paralysed
- Neonatal : commonly occurs following umbilical cord infection , due to poor umbilical cord care. It may rarely occur following ear piercing and circumcision. It Causes > 50% of deaths tetanus worldwide.
Presentation: is within a week of birth
- A short history of failure to feed/suck (failure to open mouth), vomiting, and spasms or convulsions.
- Spasms are generalized
- Mortality is high
- Poor umbilical hygiene is the major cause
- Typical history of non-immunized mother
- Entirely preventable by maternal vaccination and good cord care
Clinical features
Incubation Period : it is the time from injury to the first symptom which is 3-21 days.
Period of onset : It is the time from first symptom to the reflex spasm which is 1-7days.
In general the further the injury site is from the central nervous system, the longer the incubation period. The shorter the incubation period, the higher the chance of death. The features seen are:
- Trismus (lockjaw):usually the 1st sign noticed and its due to masseter rigidity
- Risus sardonicus: looks a grimace or sneer , from sustained contraction of the facial muscles
- Stiffness and spasms of bulbar, neck, trunk and limb muscles
- Opisthotonos (arched back)
- Board-like abdominal rigidity
- Consciousness is preserved
- Spasms of laryngeal muscles may cause fatal asphyxia
- It also causes autonomic dysfunction which presents as;
- Hyperpyrexia
- Sweating
- Peripheral vasoconstriction
- Labile/Sustained Hypertension
- Tachycardia, dysrhythmias and cardiac arrest
- Occasionally period of bradycardia & hypotension
Management
Principles of management
- NEUTRALIZE CIRCULATING TOXIN: This is done using either Human Tetanus immunoglobulin(HTIG) or Anti-Tetanus Serum(ATS)
HTIG is given at 250-500IU and it doesn’t cause serum sickness. It produces protective antibodies for about 4-6weeks
ATS is given at 10,000 Units subcutaneously. It produces protective antibodies for 7-10days and there is a high risk of serum sickness with its use.
2. CONTROL SPASMS
Spasms can be controlled by administering paraldehyde 0.3ml/kg I.M in neonates or 1ml per year of life with a maximum dose of 5ml in older children. Also Sedative-hypnotic agents e.g benzodiazepines or muscle relaxants e.g baclofen can be used.
3. CONTINUED SEDATION : can be achieved using phenobarbitone, chlorpromazine and diazepam.
4. ELIMINATE RESIDUAL INFECTION OR ERADICATE ORGANISM
- Wound debridement
- Antibiotics- Penicillin G, Metronidazole for 10-14days
- Hyperbaric Oxygen to wound site(kills obligate anaerobes die).
5. MANAGE AUTONOMIC SYMPTOMS
- Magnesium sulphate
- B-blockers
- Verapamil
- Atropine
6. SUPPORTIVE CARE
- airway management
- good nursing care
- adequate nutrition
- thromboembolism prophylaxis
7. REHABILITATION
Physiotherapy
Complications
The complications can be grouped into various systems affected:
- Respiratory
- Aspiration pneumonia
- Pulmonary embolism
- Hypoxia
- Laryngeal spasm
- Complications of prolonged assisted ventilation(e.g pneumonia)
- Musculoskeletal
- Fractures
- Tendon tear
- Muscle rupture
- Rhabdomyolysis
- Decubitus ulcer
- Deep-vein thrombophlebitis
- Renal
- Renal failure; due to dehydration, sepsis, rhabdomyolysis, altered renal blood flow
- urinary infection & stasis
- Gastrointestinal
- Hemorrhage
- Others:
- Weight loss,
- Sepsis
Differential diagnosis
- Meningitis
- Stiff- person syndrome
- Strychnine poisoning
- Dystonic drug reactions (e.g., succinyl choline, phenothiazines, metoclopramide)
- Hypocalcemic tetany
- Local Neoplasms
- Local infections
- Encephalitis
- Rabies
Prevention
- Nonspecific protection
- General health information to create awareness
- Education of birth attendants on proper cord care
- Strict hygiene in handling babies
2. Specific protection
- Supplementary immunization of women of child bearing age
- Immunization of children at proper ages including booster doses
3. Early Diagnosis and Prompt treatment.
4. Limitation of Disability.
- Rehabilitation.
Immunization program
Unimmunized or Partially Immunized Adults/Older Children
Tetanus toxoid x 3 doses
- 1st -1st contact
- 2nd – 4-8wks
- 3rd – 6 months
- First Booster 5 years after 3rd dose
- 2nd and Other Booster doses every 10 years
CHILDREN…
Pentavalent Vaccines at:
- 1st-6weeks
- 2nd- 10weeks
- 3rd- 14weeks
- 1st booster- 18months
- 2nd booster- 6years
- 3rd booster- 10 years
WOMEN OF REPRODUCTIVE AGE…
TT1- Contact
TT2- 4weeks after
TT3- 6months after or subsequent pregnancy
TT4- 1 year after or subsequent pregnancy
TT5- 1 year after or subsequent pregnancy
Prognostic indicators
- Age : outcome is bad for extremes of age
- Proximity to the CNS: the closer the infection is to the central nervous system, the worse the outcome.
- Co-morbidities: the presence of other diseases would cause a bad outcome.
- Autonomic dysfunction
- Incubation period: the longer the period the better the outcome.
- Period of onset: the longer the period of onset the better the prognosis
- Duration of each spasm
- Frequency of spasm
- Spontaneity of spasm
- Gender: Male gender have been noticed to have a bad outcome
References
- Harrison’s PRINCIPLES OF INTERNAL MEDICINE :Eighteenth Edition
- Textbook of preventive & social medicine – Park – 19th Edition
- UpToDate (http://www.uptodate.com)Ø eMedicine (http://www.emedicine.com)
- Current recommendations for treatment of tetanus during humanitarian emergencies : WHO TechnicalNote
- World Federation of Societies of Anaesthesiologists -WFSA
- CDC Article – Tetanuswww.medicalgeek.com
- Pediatrics and child health in a tropical region by azubuike and nkanginieme – 3rd edition.
- Journal of tropical pediatrics, volume 66, issue2, April 2020.