|School in Muti, Ethiopia|
Aside from protecting the vaccine recipient, one of the goals of vaccinating woman and girls who will soon be of child-bearing age against tetanus is to protect their babies from neonatal (newborn) tetanus.
Tetanus is the only vaccine-preventable disease that is not transmitted from person to person or, in the case of rabies and yellow fever (both of which I am immunized against), from animal to person. In my opinion, tetanus is one of the most frightening vaccine-preventable diseases and, to top it off, humans do not develop immunity to tetanus after being infected with the bacteria.
Tetanus is caused by a toxin produced by a bacteria, Clostridium tetani. Tetanospasmin, or tetanus toxin, is the second most poisonous substance known (the most poisonous substance is produced by a bacteria of the same genus, C. botulinum. That's right - Botox). C. tetani is found primarily in soil but is also found in the gastrointestinal tract of animal and humans.
C. tetani produces spores that are resistant to conditions that normally kill bacteria – even boiling will not kill C. tetani spores. Tetanus spores are introduced into tissue usually through wounds or, in the case of neonatal tetanus, through the umbilical stump. Tetanus has also been associated with piercings, injection drug use, chronic otitis media (ear infection), animal bites, burns, and, on rare occasions, no source of infection is identified.
CDC/ AFIP/C. Farmer
Tetanus toxin is released from the bacteria and enters motor nerves and blood. The toxin is transported to the spinal cord and brain where it blocks the action of inhibitory neurotransmitters. Reflexive responses are unopposed, resulting in painful muscle contractions. With localized tetanus, the spasms are limited to the part of the body infected with the tetanus bacteria. In generalized tetanus, every muscle group in the body contracts. Ironically, spasms of facial muscle make the person appear as if she or he is smiling. This is called risus sardonicus. A person with tetanus has no reason to smile; the muscle spasms are excruciatingly painful and consciousness is not lost, so the person remains completely aware.
People with generalized tetanus or cephalic (head) tetanus usually require critical care with endotracheal intubation and mechanical ventilation. They frequently require sedation and sometimes drug-induced paralysis to manage the spasms. People who recover from severe tetanus often have psychiatric problems as the result of their ordeal.
Tetanus vaccine is inactivated tetanus toxin, also known as tetanus toxoid. In response to the vaccine, the immune system makes antibodies to tetanus toxin. These antibodies do not kill C. tetani or prevent infection, but prevent tetanus toxin from entering the nervous system and causing tetanus. A person infected with C. tetani will need to be treated with antibiotics to kill the bacteria.
Antibodies to tetanus toxin pass through the placenta to the fetus, providing the newborn baby protection against neonatal tetanus. Babies receive their primary diphtheria, tetanus, and acellular pertussis (DTaP) series at 2, 4, and 6 months of age. Until then, they are protected by their mother's antibodies.
Adults who have received a primary diphtheria, tetanus, and pertussis series (DTP or DTaP) should receive tetanus and diphtheria (Td) boosters every ten years. Pregnant women who have completed a primary DTP/DTaP series should receive one dose of tetanus, diphtheria, and acellular pertussis vaccine (Tdap) either before becoming pregnant or after 20 weeks of gestation. Pregnant women who have not completed a tetanus primary series should receive three doses of tetanus and diphtheria vaccine (Td) including one dose of Tdap.
American College of Obstetrics and Gynecologists. (2012). Update on immunization and pregnancy: tetanus, diphtheria, and pertussis vaccination. ACOG committee opinion No. 521. Obstetrics and Gynecology, 119(3), 690-691. http://www.acog.org/Resources_And_Publications/Committee_Opinions/Committee_on_Obstetric_Practice/Update_on_Immunization_and_Pregnancy_Tetanus_Diphtheria_and_Pertussis_Vaccination.
Arnon, S. S. (2011). Tetanus (Clostridium tetani). In R. M. Kliegman, B. F. Stanton, J. W. St. Geme III, N. F. Schor, & R. E. Behrman (Eds.). Nelson textbook of pediatrics (19th Ed.). [Electronic version].
Centers for Disease Control and Prevention. (2011). Updated recommendations for use of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine (Tdap) in pregnant women and persons who have or anticipate having close contact with an infant aged <12 months – Advisory Committee on Immunization Practices (ACIP), 2011. Morbidity and Mortality Weekly Report, 60(41), 1424-1426. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6041a4.htm.
Reddy, P. & Bleck, T. P. (2010). Clostridium tetani (tetanus). In G. L. Mandell, J. E. Bennett, & R. Dolin (Eds). Mandell, Douglas, and Bennett's principles and practice of infectious diseases (7th ed.). [Electronic version].
Wassilak, S. G. F., Roper, M. H., Kretsinger, K., Orenstein, W. A. (2008). Tetanus toxoid. In S. A. Plotkin, W. A. Orenstein, & P. A. Offit (Eds) Vaccines (5th Ed.). [Electronic version].