A medical condition characterized by a prolonged contraction of skeletal muscle fibers.
The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, rod-shaped, obligate anaerobic bacterium Clostridium tetani.
Infection generally occurs through wound contamination and often involves a cut or deep puncture wound. As the infection progresses, muscle spasms develop in the jaw (thus the name “lockjaw”) and elsewhere in the body. Infection can be prevented by proper immunization or post-exposure prophylaxis.
Signs and Symptoms
Tetanus often begins with mild spasms in the jaw muscles—also known as lockjaw. The spasms can also affect the chest, neck, back, abdominal muscles, and buttocks. Back muscle spasms often cause aching called opisthotonos. Sometimes the spasms affect muscles that help with breathing, which can lead to breathing problems.
Prolonged muscular action causes sudden, powerful, and painful contractions of muscle groups, which is called “tetany”. These episodes can cause fractures and muscle tears. Other symptoms include drooling, excessive sweating, fever, hand or foot spasms, irritability, swallowing difficulty, and uncontrolled urination or defecation.
Mortality rates reported vary from 48% to 73%. In recent years, approximately 11% of reported tetanus cases have been fatal. The highest mortality rates are in unvaccinated people, people over 60 years of age, or newborns.
Tetanus is caused by the tetanus bacterium Clostridium tetani. Tetanus is often associated with rust – especially rusty nails. Objects that accumulate rust are often found outdoors, or in places that harbor anaerobic bacteria. The rust itself does not cause tetanus, nor does it contain more C. tetani bacteria. The rough surface of rusty metal merely provides a prime habitat for C. tetani endospores to reside in, and the nail affords a means to puncture skin and deliver endospores deep within the body at the site of the wound.
An endospore is a non-metabolizing survival structure that begins to metabolize and cause infection once in an adequate environment. Because C. tetani is an anaerobic bacterium, it and its endospores thrive in environments that lack oxygen. Hence, stepping on a nail (rusty or not) may result in a tetanus infection, as the low-oxygen (anaerobic) environment is caused by the oxidization of the same object that causes a puncture wound, delivering endospores to a suitable environment for growth.
Tetanus is an international health problem, as C. tetani spores are ubiquitous. The disease occurs almost exclusively in persons unvaccinated or inadequately immunized. It is more common in hot, damp climates with soil rich in organic matter. This is particularly true with manure–treated soils, as the spores are widely distributed in the intestines and feces of many animals such as horses, sheep, cattle, dogs, cats, rats, guinea pigs, and chickens. Spores can be introduced into the body through puncture wounds. In agricultural areas, a significant number of human adults may harbor the organism. The spores can also be found on skin surfaces and in contaminated heroin. Heroin users, particularly those that inject the drug, appear to be at high risk for tetanus.