Tetanus overview

# Overview
Tetanus is a medical condition that is characterized by a prolonged contraction of skeletal muscle fibers. The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, 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 in the jaw develop hence the common name, lockjaw. This is followed by difficulty swallowing and general muscle stiffness and spasms in other parts of the body. Infection can be prevented by proper immunization and by post-exposure prophylaxis.
Tetanus affects skeletal muscle, a type of striated muscle. The other type of striated muscle, cardiac or heart muscle cannot be tetanized because of their intrinsic electrical properties. In recent years, approximately 11% of reported tetanus cases have been fatal. The highest mortality rates are in unvaccinated persons and persons over 60 years of age. C. tetani, the bacteria that causes tetanus, is recovered from the initial wound in only about 30% of cases, and can be found in patients who do not have tetanus.
The clinical manifestations of tetanus are caused when tetanus toxin blocks inhibitory nerve impulses, by interfering with the release of neurotransmitters. This leads to unopposed muscle contraction and spasm. Seizures may occur, and the autonomic nervous system may also be affected. The term tetany refers to sustained muscle contraction that is not caused by tetanus.

# Historical Perspective
In 1884 Carle and Rattone discovered tetanus by injecting animals with pus from a patient who had died of tetanus. In 1924 Descombey developed the tetanus toxoid,  which was extensively utilized in the second World War.

# Classification
Tetanus can be classified with respect to its patterns of presentation into neonatal, cephalic, generalized or local.

# Pathophysiology
The bacteria that causes tetanus, Clostridium tetani is introduced into the human body usually by a wound. The toxins produced by the bacterium, utilize the blood and/or lymphatics to gain access to target tissues. The toxins can act at various places in the central nervous system, including the spinal cord, peripheral motor end plates, and the brain. They can also act on the sympathetic nervous system.

# Causes
Clostridium tetani is a rod-shaped, anaerobic bacterium of the genus Clostridium.  Like other Clostridium species, it is Gram-positive, and its appearance on a gram stain resembles tennis rackets or drumsticks. C. tetani is found as spores in soil or as parasites in the gastrointestinal tract of animals. C. tetani produces a potent biological toxin, tetanospasmin, and is the causative agent of tetanus.

# Differentiating Tetanus from other Diseases
Tetanus must be differentiated from strychnine poisoning, dental infections, drug reactions, hypocalcemia, meningitis, stroke and stiff man syndrome.

# Epidemiology and Demographics
Tetanus is an infectious disease which is not know to be contagious and can be prevented with a vaccine. There are less than 100 cases of tetanus in the US and around five deaths can be attributed to tetanus every year. There are about one million cases of tetanus reported worldwide. These according to an estimate lead to 300,000 to 500,000 deaths every year.  The incidence of tetanus in the United States is 0.01 cases per 100,000 individuals.  Tetanus is more commonly seen in Hispanics. Individuals greater than age 65 have a higher incidence of tetanus. Tetanus has a case fatality rate of 13.2%.

# Risk Factors
Clostridium tetani spores can be found in various locations including manure, soil and dust. Inhabitants of developing countries are at a higher risk of acquiring tetanus because of lack of tetanus vaccination and less focus on general hygiene. Various risk factors for tetanus include contaminated wounds, punctured wounds, crushing, burns and working in unhygienic environment.

# Screening
The United States Preventive Services Task Force (USPSTF) has not recommended any guidelines for the screening of tetanus.

# Natural History, Complications and Prognosis
Tetanus can have an incubation period of 2 to 38 days with the man being 7 to days post exposure. The presentation and progression may vary depending on the type of tetanus. Generalized tetanus can involve the respiratory muscles making it difficult to breathe. The complications of tetanus include fractures, laryngospasm, aspiration pneumonia and pulmonary embolism. Tetanus has a fatality rate of almost 11%. The fatality rate of tetanus might be associated with prolonged  convulsions and contractions. Tetanus without spasms has an excellent prognosis. Early diagnosis is also associated with a good prognosis.

# Diagnosis

## History and Symptoms
The history of a patient presenting with tetanus typically reveals soil, rust containing metal or manure related contamination of an injury or a wound. Punctured wounds, burns, scratches by animals,  fractures, otitis media and surgical wounds that are contaminated, these can be related to surgeries on the gastrointestinal tract or abortions. History of recent accident or an injury leading to break in the continuity of the skin in the a contaminated environment is helpful in making a diagnosis. Trismus, or lockjaw, spasms of the facial muscles (risus sardonicus), neck stiffness and swallowing difficulty are some important symptoms of tetanus.

## Physical Examination
Tetanus may initially present with muscle stiffness. The distribution may vary with the type of tetanus. Maseters are commonly involved initially with an  accompanying headache. Neck stiffness, difficulty swallowing, spasms involving various muscles groups including the abdominal muscles and sweating may be seen later in the disease.

## Laboratory Findings
Tetanus is a clinical diagnosis and there are no laboratory findings characteristic of tetanus. The diagnosis is based on the a detailed history and a thorough physical exam. Bacteriologic confirmation is not required. C. tetani can be found in individuals without tetanus and only 30% of tetanic wounds may yield the pathogen.

## Xray
Tetanus is clinical diagnosis and there are no x ray findings associated with tetanus.

## CT scan
Tetanus is clinical diagnosis and there are no CT scan findings associated with tetanus.

## MRI
Tetanus is clinical diagnosis and there are no MRI findings associated with tetanus.

## Ultrasound
Tetanus is clinical diagnosis and there are no ultrasound findings associated with tetanus.

## Other Imaging Studies
Tetanus is clinical diagnosis and there are no other imaging studies done for tetanus.

## Other Diagnostic Studies
Tetanus is clinical diagnosis and other diagnostic studies are not done for tetanus.

# Treatment

## Medical Therapy
Tetanus is a medical emergency. Medical therapy includes hospitalization, immediate treatment with human tetanus immune globulin (TIG) (or equine antitoxin if human immune globulin is not available), a tetanus toxoid booster, agents to control muscle spasm, aggressive wound care, and antimicrobial therapy. Mechanical ventilation and agents to control autonomic nervous system instability may be required among patients with severe disease.

## Surgery
The only surgical intervention required for the management of tetanus is wound debridement. The contaminated wound must always be cleaned.

## Primary Prevention
A very common primary prevention method for tetanus is vaccinating against the bacteria which causes tetanus, Clostridium tetani. Other methods of primary prevention include proper wound care, avoiding injuries, wearing protective equipment when playing, keeping surroundings clean, controlling diabetes, ensuring aseptic gynecological procedures,  aggressively managing burn and compound fracture injuries and avoiding IV drug abuse

## Secondary Prevention
Tetanus vaccine can prevent Tetanus for approximately 10 years. Post-exposure care is indicated in people who do not know exactly when their last Tetanus booster was and who did not complete their primary prevention set of vaccinations. These patients will typically receive passive immunity with tetanus immune globulin (TIG).

## Cost-Effectiveness of Therapy
The major cost encountered with tetanus is in the form of the vaccine. There are many different trade names associated with the tetanus vaccine that come with slightly different costs. The prices of the vaccines are all listed in the following tables. The tables are separated based upon pediatric doses versus adult doses. The DTaP vaccine that is mentioned in the passage stands for Diptheria, Tetanus, and Pertussis.