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Tetanus is caused by a bacteria called
Clostridium tetani, whose spores (the dormant form) are found in
soil, street dust, and animal (or even human) feces. Tetanus spores
germinate in the body, producing a highly poisonous neurotoxin in
the blood, spreading to the nervous system. The infection is usually
transmitted through deep puncture wounds or cuts or scratches that
are not cleaned well. Between 1997 and 1999, approximately 64% of
tetanus cases in the United States were associated with such wounds
as punctures, lacerations, or abrasions. Many people associate
tetanus with rusty nails and other dirty objects, but any wound can
be a source. Less common ways of getting tetanus are animal
scratches and bites, surgical wounds, dental work, and therapeutic
abortion. About 18% of cases reported between 1997 and 1999 were a
result of intravenous drug use. Cases have also been reported in
people with no known wound or medical condition.
The first symptom of tetanus is often a stiff or
"locked" jaw that prevents the patient from opening his/her mouth or
swallowing. This is also called trismus and results in a facial
expression called a sardonic smile (or risus sardonicus). Stiffness
of the neck and other muscles throughout the body and uncontrollable
spasms often follow. Sometimes these convulsions are severe enough
to cause broken bones. The bacterial toxin (tetanospasmin)
affects the nerve endings, causing a continuous stimulation of
muscles. Other symptoms include irritability, restlessness, loss of
appetite, and drooling. People with tetanus that is localized
experience pain and tingling only at the wound site and spasms in
nearby muscles.
In the underdeveloped world, neonatal tetanus
accounts for about one-half of tetanus deaths and is related to
infection of the umbilical stump in a baby born of an unimmunized
mother. The Centers for Disease Control and Prevention (CDC)
estimate that over 270,000 deaths occur annually worldwide as a
result of neonatal tetanus. In contrast, only two cases of neonatal
tetanus in the United States were reported to the CDC between 1989
and 1999. Mothers who have been adequately immunized against tetanus
protect their newborns by passing the antibody through the placenta. |
