Do You Need a Tetanus Shot?

Tetanus is an acute, often fatal illness that occurs throughout the world. It is caused when spores of a deadly bacterium–Clostridium tetani–enter a wound and excrete a poisonous toxin called ‘tetanospasmin’ which blocks the relaxation of muscles.

C. tetani spores can only grow in environments without exposure to oxygen and are extremely difficult to kill as they are resistant to heat and many antiseptics. C. tetani spores are typically found in the soil and in feces of many farm animals and humans. We tend to think of stepping on a rusty nail as the primary method of contracting tetanus, but many other types of injuries can also lead to tetanus, including frostbite, surgical wounds, animal bites, crush wounds, tattooing and body piercing and IV drug use.

The incubation period of tetanus is between two and 50 days, but most symptoms occur about eight days after infection. Tetanus affects the central nervous system and leads to stiffness and muscular rigidity and convulsive muscle spasms. The symptoms may be localized to the area surrounding the wound, though in 80 percent of cases, they are generalized and affect the entire body. The most common symptom is a stiff jaw, also called ‘lockjaw.’ Spasms may be so severe that the victim breaks bones. Spasms of the diaphragm and the vocal cords may ultimately lead to difficulty breathing and death. In the United States, 25 percent of those who contract generalized tetanus die. There is no lab test to diagnose tetanus and the diagnosis is made purely by observing the clinical signs and symptoms.

Tetanus is very rare in people who are up-to-date with their tetanus vaccination schedule. This is most commonly accomplished by completing a series of three shots in childhood followed by a booster shot every 10 years. In the United States, adults over 50 years old account for 70 percent of tetanus infections–likely due to their failure to keep up with their booster shots. The tetanus vaccine is recommended by the Centers for Disease Control and Prevention (CDC), the American Academy of Family Physicians (AAFP) and the American College of Physicians (ACP). In adults, the traditional booster shot has been the Td shot which combines the tetanus immunization with an immunization for diphtheria. The Td shot is almost 100 percent effective for adults receiving the correct initial shots of three immunizations (either as a child or as an adult) and a routine booster every 10 years.

On a related note, cases of pertussis (whooping cough) are increasing in children and adults. Although children are routinely immunized against pertussis with their three-shot tetanus vaccination series, it seems that this may not provide adequate protection to adults who may become ill themselves or pass the disease on to small children, particularly those under 12 months of age. As a result, in 2005, a new tetanus vaccine that includes protection against pertussis was developed–the Adacel vaccine or Tdap. The vaccine is recommended to be given to adults aged 19-64 years to replace a 10-year booster shot of Td. After receiving a single dose of Tdap, adults should receive the standard Td booster every 10 years. If an adult wants extra protection against pertussis (for example, adults with close contact with an infant younger than 12 months), he or she may receive a single dose of Tdap after an interval as short as two years since their last Td booster. The Tdap vaccine is not approved for adults over 65 years of age.

Td and Tdap should not be given to patients who have had a previous serious allergic reaction to that vaccine. The most common side effects are redness nodules and pain at the injection site. These symptoms resolve spontaneously and do not require medical attention.

Dr. McMahon, a graduate of Yale University and the University of Pittsburgh School of Medicine, is board certified in Internal Medicine. She is a member of the American College of Physicians and the Allegheny and Pennsylvania Medical Societies. She is in solo practice in the North Hills.