Tetanus

What is tetanus?

• Tetanus is a disease caused by tetanospasmin , a neurotoxin produced by Clostridium tetani

• medical condition characterized by a prolonged contraction of skeletal muscles fibers.

• Infection generally occurs through wound contamination and often involves a cut or deep puncture wound.

• Vaccine-preventable disease that is infectious but is not contagious

Epidemiology & Incidence

• International health problem -C. Tetani spores are ubiquitous.

• Persons unvaccinated/inadequately immunized.

• Common in hot, damp climates with soil rich in organic matter - fertilizer-treated soils, as the spores are widely distributed in the intestines and feces of animals such as horses, sheep, cattle, dogs, cats, rats, guinea pigs, and chickens.

• In agricultural areas, a significant number of human adults may harbor the organism.

• Spores are introduced into the body through puncture wounds-also found on skin surfaces and in contaminated heroin addicts.

• IVDU’s are at high risk . • Tetanus – in particular, the neonatal form – remains a

significant public health problem in non-industrialized countries.

• The WHO estimates that 59,000 newborns worldwide died in 2008 as a result of neonatal tetanus.

– In the U.S, 50-100 people is infected with tetanus each year.

• Nearly all of the cases in the U.S occur in unimmunized individuals or individuals who have allowed their inoculations to lapse.

• There has been a steady decline in the number of cases of adult tetanus in Malaysia.

– In 1995 there were 12 cases with 2 deaths reported while in 2001 only 4 cases (with no mortality) were reported.

Pathophysiology

Incubation period :

• 3 – 21 days, range from one day to several months, depending on the character , extent and location of the wound

• most cases occurs within 14 days

Damaged tissue

endospores of Clostridium tetani

neurotoxin tetanospasmin

Anaerobic enviroment ( active)

NMJ

retrograde axonal transport to cell bodies in the spinal cord and brain stem

binds irreversibly to receptors - gangliosides and blocks the inhibitory neurotransmitters glycine and gammaaminobutyric acid.

• Damaged UMN can no longer inhibit LMN

– Inability to control reflex responses to afferent sensory stimuli, This results in unopposed muscle contractions.

• Both mechanisms produce the hallmark muscle rigidity and spasms.

• Likewise, a lack of neural control of the adrenal glands results in release of catecholamines, thus producing a hypersympathetic state and widespread autonomic instability.

Clinical Features :

On the basis of clinical findings, four different forms of tetanus have been described:

General Localized Neonatal Cephalic

Generalized tetanus• Commonest type , 80% of cases. • Usually presents with a descending pattern.• 1st sign is trismus/ lockjaw, and the facial spasms called

risus sardonicus, followed by stiffness of the neck, dyspagia, and rigidity of pectoral and calf muscles.

• Spasms may occur frequently and last for several minutes with the body shaped into a characteristic form called opisthotonos.

(Spasms continue for up to 4 weeks, and complete recovery may take months)

• Other symptoms include hyperpyrexia, sweating, hyper/hypotension, and episodic tachycardia.

Neonatal tetanus

• a form of generalized tetanus that occurs in newborns.• not acquired passive immunity because the mother has never

been immunized• infection of the unhealed umbilical stump, particularly when

the stump is cut with a non-sterile instrument.• common in many developing countries and is responsible for

about 14% (215,000) of all neonatal deaths, but is very rare in developed countries.

Local tetanus • Uncommon form of the disease, in which patients have

persistent contraction of muscles in the same anatomic area as the injury.

• The contractions may persist for many weeks before gradually subsiding. Local tetanus is generally milder; only about 1% of cases are fatal, but it may precede the onset of generalized tetanus.

Cephalic tetanus

• Rare form of the disease, occasionally occurring with otitis media (ear infections) in which C. tetani is present in the flora of the middle ear, or following injuries to the head.

• There is involvement of the cranial nerves, especially in the facial area.

Causes

• Contaminated wounds are the sites where tetanus bacteria multiply. Deep wounds or those with devitalized (dead) tissue

• Puncture wounds, such as those caused by nails, splinters, or insect bites, are favorite locations of entry for the bacteria. The bacteria can also be introduced through burns, any break in the skin, and injection-drug sites.

• Tetanus can also be a hazard to both the mother and newborn child (by means of the uterus after delivery and through the umbilical cord stump).

Diagnosis

• Clinically based on the presence of trismus, dysphagia, generalized muscular rigidity, and/or spasm.

• No specific laboratory tests exist for determining the diagnosis of tetanus.

• Laboratory studies may demonstrate a moderate peripheral leukocytosis.

Other Tests

• An assay for antitoxin levels is not readily available. However, a level of 0.01 IU/mL or greater in serum is generally considered protective, making the diagnosis of tetanus less likely.

• Cerebrospinal fluid (CSF) study findings are usually within normal limits.

Procedures• The spatula test is a diagnostic bedside test.

• simple test involves touching the oropharynx with a spatula or tongue blade.

• elicits a gag reflex, and the patient tries to expel the spatula (ie, a negative test result).

• If patients develop a reflex spasm of the masseters and bite the spatula (ie, a positive test result).

• In 400 patients, this test had a sensitivity of 94% and a specificity of 100%.

• No adverse sequelae (eg, laryngeal spasm) from this procedure were reported.

Treatment• The wound must be cleaned. • Dead and infected tissue should be debrided. • Administration of the antibiotic metronidazole decreases the

number of bacteria but has no effect on the bacterial toxin. • Penicillin was once used to treat tetanus, but is no longer the

treatment of choice, owing to a theoretical risk of increased spasms. However, its use is recommended if metronidazole is not available.

• Passive immunization with human anti-tetanospasmin immunoglobulin or tetanus immunoglobulin is crucial. If specific anti-tetanospasmin immunoglobulin is not available, then normal human immunoglobulin may be given instead. All tetanus victims should be vaccinated against the disease or offered a booster shot.

Mild tetanus

Mild cases of tetanus can be treated with:

• Tetanus immunoglobulin IV or IM• metronidazole IV for 10 days• Diazepam

Severe tetanus

In addition to the measures listed above for mild tetanus:

• ICU care. • human tetanus immunoglobulin injected intrathecally (increases clinical

improvement from 4% to 35%)• tracheotomy and mechanical ventilation for 3 to 4 weeks• magnesium, as an intravenous (IV) infusion, to prevent muscle spasm• diazepam as a continuous IV infusion

• the autonomic effects of tetanus can be difficult to manage (alternating hyper- and hypotension hyperpyrexia/hypothermia) and may require IV labetalol, magnesium, clonidine, or nifedipine.

– In order to survive a tetanus infection, the maintenance of an airway and proper nutrition are required.

– intake of – 3500-4000 calories, – 150 g of protein per day, is often given in liquid form through

a tube directly into the stomach (Percutaneous endoscopic gastrostomy), or through a drip into a vein (Total parenteral nutrition).

– This high-caloric diet maintenance is required because of the increased metabolic strain brought on by the increased muscle activity.

Full recovery takes 4 to 6 weeks because the body must regenerate destroyed nerve axon terminals.

Prevention

• Unlike many infectious diseases, recovery from naturally acquired tetanus does not usually result in immunity to tetanus.

• extreme potency of the tetanospasmin toxin; even a lethal dose of tetanospasmin is insufficient to provoke an immune response.

• Tetanus can be prevented by vaccination with tetanus toxoid. • CDC recommends that adults receive a booster vaccine every

10 years, and standard care practice in many places is to give the booster to any patient with a puncture wound who is uncertain of when he or she was last vaccinated, or if he or she has had fewer than three lifetime doses of the vaccine.

• Booster may not prevent a potentially fatal case of tetanus from the current wound, however, as it can take up to 2 weeks for tetanus antibodies to form.

• In children under the age of 7, the tetanus vaccine is often administered as a combined vaccine, DPT/DTaP vaccine, which also includes vaccines against diphtheria and pertussis.

• For adults and children over seven, the Td vaccine (tetanus and diphtheria) or Tdap (tetanus, diphtheria, and acellular pertussis) is commonly used.

Nature of vaccines:

• Tetanus vaccine is a toxoid prepared by extraction of the toxin from culture of C.tetani. The cell-free product is detoxified after treatment with formaldehyde.

• The antigenic potency is expressed as international immunising units (iiu or iu) by WHO. Each toxoid dose should contain no less than 40iu.

Mode of administration and dosing regimen

• Td(Tetanus toxoid+Adult Diphtheria toxoid) is administered by giving 0.5ml by Deep I.M.

• It can be administered with other vaccines as long as different syringes and different anatomic sites are used.

• A primary series for adults is three doses of preparations containing tetanus and diphtheria toxoids, with the first two doses given at least 4 weeks apart and the third dose given 6-months after the second.

Contraindications and adverse reactions• Although no evidence suggests that diphtheria and tetanus

toxoids are teratogenic, waiting until the 2nd trimester of pregnancy to administer Td is a reasonable precaution.

• Local reactions (erythema and induration, with or without tenderness)

• Fever and other systemic symptoms are less common.

• Arthus-type hypersensitivity reactions, characterized by severe local reactions starting 2-8 hours after an injection and often associated with fever and malaise, may occur, particularly among persons who have received multiple boosters of tetanus toxoid, adsorbed . Rarely, severe systemic reactions, such as generalized urticaria, anaphylaxis, or neurologic complications, have been reported

Evidence for effectiveness

• Essentially all adult vaccines achieve and maintain protective antitoxin levels for years.

• A Swedish study showed that the vaccine had a long-term efficacy rate of 94% after 10years

• Studies done in Denmark show efficacy rates of 96% after 13 to 14 years and 72% after 25 years

• In one study, however, only 77% of elderly subjects had protective antitoxin levels 8 years after receiving a primary 3 –dose series. Therefore, booster doses are recommended every 10 years3,4.

• The WHO certifies countries as having eliminated maternal or neonatal tetanus. Certification requires at least two years of rates < 1 case per 1000 live borns.– In 1998 in Uganda, 3,433 tetanus cases were recorded in

new-born babies; of these, 2,403 died. After a major public health effort Uganda in 2011 was certified as having eliminated tetanus.

• Thank you