Transcript Tetanus
Tetanus Tetanus Caused by Clostridium Tetani Gram positive Spore-forming Anaerobic rod Reservoir Spores of C. tetani are found in soils throughout the world Spores are very resistant to harsh conditions heat radiation chemicals drying Spores can survive for a long time in environment---100yrs possibly! Tetanus (cont’d) Entry of C. tetani into the body usually involves implantation of spores into a wound After gaining entry, C. tetani spores can persist in the body for months, waiting for the proper low oxygen growth conditions to develop Tetanus (cont’d) When the oxygen levels of the surrounding tissue is sufficiently low, the implanted C. tetani spore then germinates into a new, active vegetative cell that grows and multiplies and most importantly produces tetanus toxin Tetanus (cont’d) The virulence factor (toxin) responsible for the symptoms of tetanus is called tetanospasmin Tetanospasmin is an extremely lethal neurotoxin Induces spastic paralysis by inhibiting release of inhibitory neurotransmitters Physiologic consequence is uncontrolled muscle contractions Tetanus (cont’d) As growing cells of C. tetani produce tetanospasmin at the wound site, the toxin starts to migrate along nerves into the Central Nervous System where it blocks the release of inhibitory neurotransmitters As a consequence of too much “activator transmitters”, muscles are OVERstimulated to repeatedly contract—called spastic paralysis Tetanus (cont’d) A person suffering from tetanus undergoes convulsive muscle contractions of the jaw--called LOCKJAW The contractions by the muscles of the back and extremities may become so violent and strong that bone fractures may occur Unfortunately, the affected individual is conscious throughout the illness, but cannot stop these contractions Tetanus (cont’d) Death may occur from tetanus, often from cardiac (heart) and respiratory (lung) effects or secondary complications from the infection Diagnosis of Tetanus Tetanus is suspected upon exposure to a bite or puncture wound Because C. tetani exhibits such exquisite sensitivity to oxygen, it is very difficult to recover and/or grow from clinical specimens As a result, diagnosis is made on the basis of clinical findings and history Tetanus (cont’d) Tetanus is not common in U.S.A. because of mandatory vaccination However, a few cases/year in nonvaccinated or improper booster individuals Tetanus is still very common in Third World countries—causing several hundred thousand deaths per year Many of these deaths involve neonatal tetanus due to the umbilical cord being unsterilely cut Treatment of Tetanus Very difficult to treat once symptoms have developed Antitoxin is administered Muscle relaxants Supportive therapy (ventilator) Cleansing of the wound Treatment of Tetanus (cont’d) If recovery does occur, there are usually no long-term side effects. Recovered individuals do not necessarily develop “natural Immunity” against the infection--because the very small amount of tetanus toxin produced during the infection does not elicit a strong, protective immune response which would produce enough antibodies against future re-infection Prevention of Tetanus A highly effective vaccine is available Tetanus immunity is achieved using a formalized tetanus toxoid Toxoid is administered as part of the childhood DPT vaccine 4 primary immunizations starting at 2 months of age Boosters every 10 yrs they *&!@# hurt!!