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TETANUS. Tetanus is an acute disease caused by an exotoxin produced by Clostridium tetani. It is characterized by generalized rigidity and convulsive spasms of skeletal muscles. The muscle stiffness usually involves the jaw and neck and then becomes generalized. TETANUS.
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TETANUS • Tetanus is an acutedisease caused by an exotoxinproduced by Clostridium tetani. • It is characterized by generalizedrigidityand convulsive spasms of skeletal muscles. The musclestiffness usually involves the jaw and neck and thenbecomes generalized.
TETANUS • Infection generally occurs through wound contamination and often involves a cut or deep puncture wound.
How serious is tetanus? • Tetanus has a high fatality rate: about 10% of reported cases result in death.
TETANUS • C. tetani is an anaerobic gram-positive bacillus ( spore-forming bacteria) • Spores found in soil, dust, animal feces; may persist for months to years • Tetanus is not spread from person to person Spores are introduced into tissues after a penetrating injury.
Neurotoxins in tetanus Clostridium tetani produces two exotoxins: 1.tetanolysin (the function is not known) 2.tetanospasmin (a neurotoxin which causes the clinical manifestations)
Tetanus • Tetanus toxin blocks inhibitory nerve impulses, by preventing the release of inhibitory neurotransmitters GABA (gamma-aminobutyric acid) and glycine. http://www.bilkent.edu.tr/~bilheal/aykonu/ay2005/mart05/tetanoz.html
Pathogenesis • Tetanus toxin produced in a wound can spread centrally via intra-axonal transport along motor nerves to the spinal cord; • it may also spread hematogenously. Toxin binds in central nervous system and interferes with neurotransmitter release to block inhibitor impulses
TETANUS • Tetanus - is rare in industrialized countries because of the widespread use of active immunization. • In the United States, fewer than 50 cases are reported annually; at least 87% occur in inadequately immunized persons, and 35% occur in persons older than 60 years, which emphasizes the need to maintain immunity in older adults.
TETANUS • Tetanus may also occur in association with: -pregnancy (postpartum and postabortion tetanus), -surgery (postoperative tetanus), -burns, vaccination, intramuscular injections, gangrene, chronic skin ulcers, dog bites, penetrating eye injuries, and narcotics addiction -umbilical stump infection in newborns (neonatal tetanus) • In 10% to 20% of patients with tetanus, there is no history of injury or evidence of an infected lesion
Pathogenesis • The incubation period between injury and onset of symptoms ranges from 1 to 55 days. In more than 80% of patients, symptoms begin within 14 days. • The length of the incubation period is a valuable prognostic sign in patients younger than 50 years: - mortality is almost 100% when this period is only 1 or 2 days but 35% to 40% when it is more than 10 days.
Tetanus • Terms describing the initial stages of tetanus include the incubation period (time fran inoculation to the first symptoms) and the period of onset (time from the first symptom to the first generalized spasm) The shorter these periods are, the higher the risk of death is.
Tetanus Clinical Forms • Clinical forms: • local (not common), • cephalic (rare), • generalized (most common, representing 80% of cases) • neonatal tetanus
Generalized tetanus The usual presenting symptoms are: • restlessness; • pain caused by muscle spasm; • stiffness of the back, neck, thighs and abdomen. • difficulty in opening the mouth (trismus, or lockjaw-masseter rigidity), the hallmark of tetanus; this is the first symptom in more than 50% of patient • risus sardonicus (facial spasm / sneering expression)
Generalized tetanus • The generalized spasm consists of opisthotonic posturing with flexion of the arms and extension of the legs. • During the spasm, the upper airway can be obstructed, or the diaphragm may participate in general muscular contraction.
Generalized tetanus • Sudden stimuli (e.g., bright light or noise) can precipitate tonic seizure, accompanied by diaphragmatic, intercostal, glottal, or laryngeal spasm, and result in hypoxia and respiratory arrest • Spasms may occur frequently and last for several minutes. • Spasmscontinue for 3–4 weeks.
Generalized tetanus • Labile hypertension, tachycardia, arrhythmias, profuse sweating, marked intermittent vasoconstriction, tachypnea, and hypotension may occur singly or in varying combinations.
Generalized tetanus • The complications of tetanus are respiratory arrest secondary to tetanic spasms, pneumonia secondary to aspiration, pulmonary emboli, cardiac problems related to sympathetic overactivity or to cardiomyopathy, fractures of thoracic vertebrae caused by violent spasms.
Cephalic tetanus Is a rare form of the disease, occasionallyoccurring with otitis media (ear infections) in which C. tetani ispresent in the flora of the middle ear, or following injuries to thehead. There is involvement of the cranial nerves, especially in thefacial area.
Localized tetanus • Localized tetanus is characterized by intermittent painful spasms of muscles in the same anatomic area as the injury • The stiffness and spasms may persist for weeks in the local area and then gradually abate. • Local tetanus mayprecede the onset of generalized tetanus, but is generally milder. Only about 1% of cases are fatal.
Neonatal tetanus • Generalized tetanus in newborns • It occurs through infection of unhealed umbilical stump if mothers are inadequately immunized.
Tetanus • Tetanus is diagnosed by clinical observation. There are currently no blood test that can be used to diagnose tetanus.
Laboratory findings • Blood counts, blood chemistries, and CSF values are normal. • C. tetani is isolated from the wound in only 30% of cases, probably because of the fastidious anaerobic requirements of the organism.
Differential Diagnosis • Trismus may also be present in patients with encephalitis, but in contrast to those with tetanus, these patients are not fully conscious. • Acute strychnine poisoning is the only disease that resembles tetanus. • Hepatic encephalopathy is sometimes associated with prominent muscular stiffness and rigidity.
Treatment of tetanus • Treatment of tetanus is aimed at prevention of muscle spasms and respiratory complications, neutralization of circulating toxin, and elimination of the source of the toxin.
Tetanus antitoxin • Human tetanus immune globulin (HTIG) is recommended for persons withtetanus. • TIG can only help remove unbound tetanus toxin. Itcannot affect toxin bound to nerve endings. • A single intramusculardose of 5000 units is generally recommended for childrenand adults, with part of the dose infiltrated around the wound if itcan be identified.
Control of muscular spasms and rigidity • Sedation requires prevent respiratory depression • Diazepam is the drug of choice produces a sedative effect without inducing depression • Magnesium intravenous infusion prevents muscule spasm.
Control of sympathetic overactivity • Propranolol and labetalol are examples of beta-adrenergic blocking agents that have been used in patients with tetanus to treat marked sympathetic overactivity, including hypertension, tachycardia, and profuse sweating.
Immunization • Infants should receive diphtheria-pertussis-tetanus (DPT) vaccine at 2 months of age. Two additional doses are given at 4 and 6 months of age. A booster injection of DPT is given at 18 months and 4-6 years • At 16 years of age, a booster dose of combined adult-type tetanus and diphtheria toxoids is administered.
Immunization Teatanus-diphteria vaccine is given to adolescents and adults as a booster shot every 10 years.
Immunization • In the event of tetanus prone-injury a booster dose of vaccine should be given if more than 5 years have elapsed since last dose.
Immunization • Adults who have not been immunized should receive two doses of alum-precipitated tetanus toxoid intramuscularly, 1 month apart, followed by a booster dose after 6 months. • Patients with wounds that are contained with dirt or feces and who have not received adequate active immunization in the past 5 years or in whom immunodeficiency is suspected should receive passive immunization with HTIG (250-500 units, intramusculary) in addition to active immunization.
Dose Primary 1 Primary 2 Primary 3 Primary4 Age 2 months 4 months 6 months 15-18 months Interval --- 4 wks 4 wks 6 mos Routine DTaP Primary Vaccination Schedule
