Tetanus

Tetanus (lockjaw) is a disease in which a toxin produced by the anaerobic bacterium Clostridium tetani causes severe muscle spasms. Tetanus occurs in many parts of the world, especially in developing countries. Worldwide, as many as 50,000 people die each year from tetanus.
Spores of Clostridium tetani can live for years in animal feces and soil. Once tetanus spores gain entry into a person's body-typically through a wound-they begin to grow (germinate). Only growing tetanus bacilli produce toxin; it is the toxin-not the bacteria themselves-that causes disease. Tetanus sometimes develops after cuts with dirty, rusty objects or deep punctures from stepping on a nail; the infection can also result from clean, superficial wounds. Injecting drug users and people with burns or surgical wounds are at particular risk of developing tetanus. After childbirth, tetanus infection of the woman's uterus and the umbilical stump of the newborn (tetanus neonatorum) can occur-a hazard in developing countries.

Symptoms
Symptoms usually appear 5 to 10 days after infection, but they can start as soon as 2 days or as late as 50 days after infection. The most common symptom is stiffness of the jaw, which accounts for the name "lockjaw."
Other symptoms include restlessness, difficulty in swallowing, irritability, headache, fever, sore throat, chills, and muscle spasms and stiffness in the neck, arms, and legs. As the disease progresses, a person may have difficulty opening the jaw (trismus). Spasm of the facial muscles produces a facial expression of a fixed smile and raised eyebrows (risus sardonicus).
Rigidity or spasm of abdominal, neck, and back muscles can cause a distinctive posture with the head and heels pulled back and the body arched forward (opisthotonos) . Spasms of sphincter muscles in the lower abdomen can lead to constipation and retention of urine.
Minor disturbances- such as noise, a draft, or the bed being jarred-can trigger painful muscle spasms and profuse sweating. During full-body spasms, a person cannot cry out or speak because of rigid chest muscles or throat spasm. This condition also prevents normal breathing, causing oxygen deprivation or fatal suffocation. Tetanal spasms may be limited to muscle groups near the wound. Such local tetanus may persist for weeks.

Diagnosis & Prognosis
A doctor suspects tetanus when muscle stiffness or a spasm occurs after a person has suffered a wound. Although Clostridium tetani can sometimes be cultured from a swab sample taken from the wound, negative culture results do not always mean tetanus is not present.
Tetanus has a worldwide mortality rate of 50%. Death is most likely in injecting drug users, the very young, and the very old. The prognosis is grave if symptoms worsen rapidly or treatment is delayed.

Prevention
Preventing tetanus is far better than treating tetanus once it develops. Tetanus rarely develops in a person who has completed a primary series of tetanus vaccinations (three or more injections). The tetanus vaccine stimulates the body to neutralize the toxin rather than the bacteria themselves. In young children, the tetanus vaccine is given as part of a series that includes the diphtheria and pertussis (whooping cough) vaccines. Adults who have completed the primary series of tetanus vaccination should also receive tetanus boosters every 10 years.
The guidelines for vaccination of injured people are complex: in general, people who have completed a primary series do not need a booster if they had one in the previous 5 years. People who have not completed a primary series or who have gone more than 10 years without a booster require a booster and may also require tetanus immune globulin.
The other preventive measure is prompt, thorough cleaning of wounds (especially deep puncture wounds), because dirt and dead tissue promote the growth of Clostridium tetani. Surgical removal of foreign material and damaged tissue may be necessary.

Treatment
Once symptoms of tetanus appear, the person is hospitalized and kept in a quiet room. Antibiotics (for example, metronidazole, penicillin, or tetracycline) are given to kill the bacteria and prevent further production of toxin; however, antibiotics have no effect on toxin that has already been produced. Tetanus immune globulin is given to neutralize the toxin. Other drugs may be given to provide sedation; relax the muscles; relieve pain; and control seizures, heart rate, and blood pressure.
For people with moderate to severe infections, a ventilator may be required to assist breathing. Because people with tetanus have trouble swallowing, nourishment is given intravenously or through a tube inserted through the nose and into the stomach.
Although many other diseases (for example, chickenpox) leave a person immune to further episodes of the disease, people who survive a tetanus infection are not immune to tetanus. Thus, the full series of vaccinations must be given after the person recovers.
[Merck]