Sunday, March 18, 2012

Tetanus (lockjaw)

School in Muti, Ethiopia
One of the more enjoyable outreaches that I did while working in Ethiopia was going out to schools to vaccinate school-aged girls and young women (we vaccinated the boys too but, according to the Ethiopian Ministry of Health immunization schedule, we weren't supposed to). We would hike to villages where at least some of the children had never seen a faranji. Watching their reaction to me was fun. First they'd be a little frightened, and then they'd get curious - they'd sneak up behind me, quickly touch my skin or my hair, and then run away. Once the children had warmed up to me, I'd spend a little time playing with them before we had to hike back to the health center.

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.

Risus sardonicus
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.

Neonatal tetanus
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.

Additional information


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.

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.

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].


  1. How many cases of tetanus were in the US last year? How many people are there in the US? And finally, please provide the studies that show dtap is safe during pregnancy.

    1. The most recent summary of notifiable diseases is for 2009: there were 18 cases of tetanus in the U.S. in 2009.

      According to the U.S. Census Bureau, the current population of the U.S. is 313,218,301

      DTaP is not given to adults.

      The Advisory Committee on Immunization Practices (CDC, 2011) cites two published studies that "[do] not suggest any elevated frequency or unusual patterns of adverse events in pregnant women who received Tdap and that the few serious adverse events reported were unlikely to have been caused by the vaccine."

      Gall et al. (2011). Maternal immunization with tetanus-diphtheria-pertussis vaccine: effect on maternal and neonatal serum antibody levels. Am J Obstet Gynecol, 204.

      Talbot et al. (2010). The safety of immunizing with tetanus-diphtheria-acellular pertussis vaccine (Tdap) less than 2 years following previous tetanus vaccination: experience during a mass vaccination campaign of healthcare personnel during a respiratory illness outbreak. Vaccine, 28.

      The ACIP continues:
      "Both tetanus and diphtheria toxoids (Td) and tetanus toxoid vaccines have been used extensively in pregnant women worldwide to prevent neonatal tetanus. Tetanus- and diphtheria-toxoid containing vaccines administered during pregnancy have not been shown to be teratogenic."

      Czeizel & Rockenbauer. (1999). Tetanus toxoid and congenital abnormalities. Int J Gynecol Obstet.

      Silveria et al. (1995). Safety of tetanus toxoid in pregnant women: a hospital-based case-control study of congenital anomalies. Bull World Health Organ 1995