Tetanus is caused by the tetanus bacterium Clostridium tetani.[22] Tetanus is an international health problem, as C. tetani spores are ubiquitous. Spores can be introduced into the body through a puncture wound (penetrating trauma). Due to C. tetani being an anaerobic bacterium, it and its endospores thrive in environments that lack oxygen, such as a puncture wound.
The disease occurs almost exclusively in persons inadequately immunized.[23] It is more common in hot, damp climates with soil rich in organic matter. Manure-treated soils may contain spores, as they are widely distributed in the intestines and feces of many animals such as horses, sheep, cattle, dogs, cats, rats, guinea pigs, and chickens.[8] 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.[8] Heroin users, particularly those that inject the drug subcutaneously, appear to be at high risk of contracting tetanus.[8] Rarely, tetanus can be contracted through surgical procedures, intramuscular injections, compound fractures, and dental infections.[24] The bite of a dog can transmit tetanus.[25]
Tetanus is often associated with rust, especially rusty nails. Although rust itself does not cause tetanus, objects that accumulate rust are often found outdoors or in places that harbour anaerobic bacteria. Additionally, the rough surface of rusty metal provides a habitat for C. tetani, while a nail affords a means to puncture skin and deliver endospores deep within the body at the site of the wound.[26] An endospore is a non-metabolizing survival structure that begins to metabolize and cause infection once in an adequate environment. Hence, stepping on a nail (rusty or not) may result in a tetanus infection, as the low-oxygen (anaerobic) environment may exist under the skin, and the puncturing object can deliver endospores to a suitable environment for growth.[27]
There are currently no blood tests for diagnosing tetanus. The diagnosis is based on the presentation of tetanus symptoms and does not depend upon isolation of the bacterium, which is recovered from the wound in only 30% of cases and can be isolated from patients without tetanus. Laboratory identification of C. tetani can be demonstrated only by production of tetanospasmin in mice.[8] Having recently experienced head trauma may indicate cephalic tetanus if no other diagnosis has been made.
The "spatula test" is a clinical test for tetanus that involves touching the posterior pharyngeal wall with a soft-tipped instrument and observing the effect. A positive test result is the involuntary contraction of the jaw (biting down on the "spatula") and a negative test result would normally be a gag reflex attempting to expel the foreign object. A short report in The American Journal of Tropical Medicine and Hygiene states that, in a patient research study, the spatula test had a high specificity (zero false-positive test results) and a high sensitivity (94% of infected patients produced a positive test).[28]
Tetanus often begins with mild spasms in the jaw muscles—also known as lockjaw or trismus. The spasms can also affect the facial muscles resulting in an appearance called risus sardonicus. Chest, neck, back, abdominal muscles, and buttocks may be affected. Back muscle spasms often cause arching, called opisthotonos. Sometimes the spasms affect muscles that help with breathing, which can lead to breathing problems.[8]
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, difficulty swallowing, suffocation, heart attack, breathing problems, irregular heartbeat, and uncontrolled urination or defecation.[citation needed]
Even with treatment, about 10% of people who contract tetanus die.[8] The mortality rate is higher in unvaccinated people and people over 60 years of age.[8]
Incubation period[edit] => The incubation period of tetanus may be up to several months, but is usually about ten days.[9][10] In general, the farther the injury site is from the central nervous system, the longer the incubation period. The shorter the incubation period, the more severe the symptoms.[11] In neonatal tetanus, symptoms usually appear from 4 to 14 days after birth, averaging about 7 days. On the basis of clinical findings, four different forms of tetanus have been described.[8]
Generalized tetanus[edit] => Generalized tetanus is the most common type of tetanus, representing about 80% of cases. The generalized form usually presents with a descending pattern. The first sign is trismus, or lockjaw, and the facial spasms called risus sardonicus, followed by stiffness of the neck, difficulty in swallowing, and rigidity of pectoral and calf muscles. Other symptoms include elevated temperature, sweating, elevated blood pressure, and episodic rapid heart rate. Spasms may occur frequently and last for several minutes with the body shaped into a characteristic form called opisthotonos. Spasms continue for up to four weeks, and complete recovery may take months.[citation needed] Sympathetic overactivity (SOA) is common in severe tetanus and manifests as labile hypertension, tachycardia, dysrhythmia, peripheral vasculature constriction, profuse sweating, fever, increased carbon dioxide output, increased catecholamine excretion and late development of hypotension. Death can occur within four days.
Neonatal tetanus is a form of generalized tetanus that occurs in newborns, usually those born to mothers who themselves have not been vaccinated. If the mother has been vaccinated against tetanus, the infants acquire passive immunity and are thus protected.[12] It usually occurs through infection of the unhealed umbilical stump, particularly when the stump is cut with a non-sterile instrument. As of 1998 neonatal tetanus was common in many developing countries and was responsible for about 14% (215,000) of all neonatal deaths.[13] In 2010 the worldwide death toll was 58,000 newborns. As the result of a public health campaign, the death toll from neonatal tetanus was reduced by 90% between 1990 and 2010, and by 2013 the disease had been largely eliminated from all but 25 countries.[14] Neonatal tetanus is rare in developed countries.
Local tetanus[edit] => Local tetanus is an uncommon form of the disease, in which patients have persistent contraction of muscles in the same anatomic area as the injury. The contractions may persist for many weeks before gradually subsiding. Local tetanus is generally milder; only about 1% of cases are fatal, but it may precede the onset of generalized tetanus.[citation needed]
Cephalic tetanus[edit] => Cephalic tetanus is the rarest form of the disease (0.9–3% of cases)[15] and is limited to muscles and nerves in the head.[16] It usually occurs after trauma to the head area, including skull fracture,[17] laceration,[17] eye injury,[16] dental extraction,[18] and otitis media,[19] but it has been observed from injuries to other parts of the body.[20] Paralysis of the facial nerve is most frequently implicated, which may cause lockjaw, facial palsy, or ptosis, but other cranial nerves can also be affected.[18][21] Cephalic tetanus may progress to a more generalized form of the disease.[15][21] Due to its rarity, clinicians may be unfamiliar with the clinical presentation and may not suspect tetanus as the illness.[16] Treatment can be complicated as symptoms may be concurrent with the initial injury that caused the infection.[17] Cephalic tetanus is more likely than other forms of tetanus to be fatal, with the progression to generalized tetanus carrying a 15–30% case fatality rate.[15][17][21]