Tetanus in the context of Booster dose

Bacteria are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit the air, soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria play a vital role in many stages of the nutrient cycle by recycling nutrients and the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Bacteria also live in mutualistic, commensal and parasitic relationships with plants and animals. Most bacteria have not been characterised and there are many species that cannot be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.

Like all animals, humans carry vast numbers (approximately 10 to 10) of bacteria. Most are in the gut, though there are many on the skin. Most of the bacteria in and on the body are harmless or rendered so by the protective effects of the immune system, and many are beneficial, particularly the ones in the gut. However, several species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy, tuberculosis, tetanus and bubonic plague. The most common fatal bacterial diseases are respiratory infections. Antibiotics are used to treat bacterial infections and are also used in farming, making antibiotic resistance a growing problem. Bacteria are important in sewage treatment and the breakdown of oil spills, the production of cheese and yogurt through fermentation, the recovery of gold, palladium, copper and other metals in the mining sector (biomining, bioleaching), as well as in biotechnology, and the manufacture of antibiotics and other chemicals.

Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating the body's adaptive immunity, they help prevent sickness from an infectious disease. When a sufficiently large percentage of a population has been vaccinated, herd immunity results. Herd immunity protects those who may be immunocompromised and cannot get a vaccine because even a weakened version would harm them.

The effectiveness of vaccination has been widely studied and verified. Vaccination is the most effective method of preventing infectious diseases; widespread immunity due to vaccination is largely responsible for the worldwide eradication of smallpox and the elimination of diseases such as polio and tetanus from much of the world. According to the World Health Organization (WHO), vaccination prevents 3.5–5 million deaths per year. A WHO-funded study by The Lancet estimates that, during the 50-year period starting in 1974, vaccination prevented 154 million deaths, including 146 million among children under age 5. However, some diseases have seen rising cases due to relatively low vaccination rates attributable partly to vaccine hesitancy.

Vaccine equity means ensuring that everyone in the world has equal access to vaccines. The importance of vaccine equity has been emphasized by researchers and public health experts during the COVID-19 pandemic but is relevant to other illnesses and vaccines as well. Historically, world-wide immunization campaigns have led to the eradication of smallpox and significantly reduced polio, measles, tuberculosis, diphtheria, whooping cough, and tetanus.

There are important reasons to establish mechanisms for global vaccine equity. Multiple factors support the emergence and spread of pandemics, not least the ability of people to travel long distances and widely transmit viruses. A virus that remains in circulation somewhere in the world is likely to spread and recur in other areas. The more widespread a virus is, and the larger and more varied the population it affects, the more likely it is to evolve more transmissible, more virulent, and more vaccine resistant variants. Vaccine equity can be essential to stop both the spread and the evolution of a disease. Ensuring that all populations receive access to vaccines is a pragmatic means towards achieving global public health. Failing to do so increases the likelihood of further waves of a disease.

Alexandre Émile John Yersin (22 September 1863 – 1 March 1943) was a Swiss-French physician and bacteriologist. He is remembered for his work as a pioneer in microbiology and immunology. Yersin is the co-discoverer of both the Diphtheria and Tetanus toxins (1890 with Émile Roux) and of the bacillus responsible for the bubonic plague or pest (1894, with Kitasato Shibasaburō). The bacteria was later named in his honour: Yersinia pestis. Yersin also demonstrated for the first time that the same bacillus was present in the rodent as well as in the human disease, thus underlining the possible means of transmission.

The Pasteur Institute (French: Institut Pasteur, pronounced [ɛ̃stity pastœʁ]) is a French non-profit private foundation dedicated to the study of biology, micro-organisms, diseases, and vaccines. It is named after Louis Pasteur, who invented pasteurization and vaccines for anthrax and rabies. The institute was founded on 4 June 1887 and inaugurated on 14 November 1888.

For over a century, the Institut Pasteur has researched infectious diseases. This worldwide biomedical research organization based in Paris was the first to isolate HIV, the virus that causes AIDS, in 1983. It has also been responsible for discoveries that have enabled medical science to control diseases such as diphtheria, tetanus, tuberculosis, poliomyelitis, influenza, yellow fever, and plague.

Tetanus toxin (TeNT) is an extremely potent neurotoxin produced by the vegetative cell of Clostridium tetani in anaerobic conditions, causing tetanus. It has no known function for clostridia in the soil environment where they are normally encountered. It is also called spasmogenic toxin, tentoxilysin, tetanospasmin, or tetanus neurotoxin. The LD₅₀ of this toxin has been measured to be approximately 2.5–3 ng/kg, making it second only to the related botulinum toxin (LD₅₀ 2 ng/kg) as the deadliest toxin in the world. However, these tests are conducted solely on mice, which may react to the toxin differently from humans and other animals.

C. tetani also produces the exotoxin tetanolysin, a hemolysin, that causes destruction of tissues.

Clostridium tetani is a common soil bacterium and the causative agent of tetanus. Vegetative cells of Clostridium tetani are usually rod-shaped and up to 2.5 μm long, but they become enlarged and tennis racket- or drumstick-shaped when forming spores. C. tetani spores are extremely hardy and can be found globally in soil or in the gastrointestinal tract of animals. If inoculated into a wound, C. tetani can grow and produce a potent toxin, tetanospasmin, which interferes with motor neurons, causing tetanus. The toxin's action can be prevented with tetanus toxoid vaccines, which are often administered to children worldwide.

Clostridium is a genus of anaerobic, Gram-positive bacteria. Species of Clostridium inhabit soils and the intestinal tracts of animals, including humans. This genus includes several significant human pathogens, including the causative agents of botulism and tetanus. It also formerly included an important cause of diarrhea, Clostridioides difficile, which was reclassified into the Clostridioides genus in 2016.

Titus Cornelius, also known as Titus, Tye, and famously as Colonel Tye (c. 1753 – September 1780), was a slave of African descent in the Province of New Jersey who escaped from his master and fought as a Black Loyalist during the American Revolutionary War; he was known for his leadership and fighting skills. He fought with a volunteer corps of escaped Virginia Colony slaves in the Ethiopian Regiment, and he led the Black Brigade associators. Tye died from tetanus from a musket wound in the wrist following a short siege in September 1780 against Captain Joshua Huddy. He was one of the most feared and effective guerrilla leaders opposing the American patriot forces in central New Jersey.

A vaccine-preventable disease is an infectious disease for which an effective preventive vaccine exists. If a person acquires a vaccine-preventable disease and dies from it, the death is considered a vaccine-preventable death.

The most common and serious vaccine-preventable diseases tracked by the World Health Organization (WHO) are: diphtheria, Haemophilus influenzae serotype b infection, hepatitis B, measles, meningitis, mumps, pertussis, poliomyelitis, rubella, tetanus, tuberculosis, and yellow fever. The WHO reports licensed vaccines being available to prevent, or contribute to the prevention and control of, 31 vaccine-preventable infections.

Risus sardonicus or rictus grin is a highly characteristic, abnormal, sustained spasm of the facial muscles that appears to produce grinning. It may be caused by tetanus, strychnine poisoning, or Wilson's disease, and has been reported after execution by hanging.

The condition's name derives from the appearance of raised eyebrows and an open "grin", which can appear sardonic or malevolent to the lay observer, displayed by those experiencing these muscle spasms.

A tetanic contraction (also called tetanized state, tetanus, or physiologic tetanus, the latter to differentiate from the disease called tetanus) is a sustained muscle contraction evoked when the motor nerve that innervates a skeletal muscle emits action potentials at a very high rate. During this state, a motor unit has been maximally stimulated by its motor neuron and remains that way for some time. This occurs when a muscle's motor unit is stimulated by multiple impulses at a sufficiently high frequency. Each stimulus causes a twitch. If stimuli are delivered slowly enough, the tension in the muscle will relax between successive twitches. If stimuli are delivered at high frequency, the twitches will overlap, resulting in tetanic contraction. A tetanic contraction can be either unfused (incomplete) or fused (complete). An unfused tetanus is when the muscle fibers do not completely relax before the next stimulus because they are being stimulated at a fast rate; however there is a partial relaxation of the muscle fibers between the twitches. Fused tetanus is when there is no relaxation of the muscle fibers between stimuli and it occurs during a high rate of stimulation. A fused tetanic contraction is the strongest single-unit twitch in contraction. When tetanized, the contracting tension in the muscle remains constant in a steady state. This is the maximal possible contraction. During tetanic contractions, muscles can shorten, lengthen or remain constant length.

Tetanic contraction is usually normal (such as when holding up a heavy box). Muscles often exhibit some level of tetanic activity, leading to muscle tone, in order to maintain posture; for example, in a crouching position, some muscles require sustained contraction to hold the position. Tetanic contraction can exist in a variety of states, including isotonic and isometric forms—for example, lifting a heavy box off the floor is isotonic, but holding it at the elevated position is isometric. Isotonic contractions place muscles in a constant tension but the muscle length changes, while isometric contractions hold a constant muscle length.

Tetanolysin is a toxin produced by Clostridium tetani bacteria. Its function is unknown, but it is believed to contribute to the pathogenesis of tetanus. The other C. tetani toxin, tetanospasmin, is more definitively linked to tetanus. It is sensitive to oxygen.

Tetanolysin belongs to a family of protein toxins known as thiol-activated cytolysins, which bind to cholesterol. It is related to streptolysin O and the θ-toxin of Clostridium perfringens. Cytolysins form pores in the cytoplasmic membrane that allows for the passage of ions and other molecules into the cell. The molecular weight of tetanolysin is around 55,000 daltons.

Benzylpenicillin, also known as penicillin G (PenG) or BENPEN, is an antibiotic used to treat a number of bacterial infections. This includes pneumonia, strep throat, syphilis, necrotizing enterocolitis, diphtheria, gas gangrene, leptospirosis, cellulitis, and tetanus. It is not a first-line agent for pneumococcal meningitis. Due to benzylpenicillin's limited bioavailability for oral medications, it is generally taken as an injection in the form of a sodium, potassium, benzathine, or procaine salt. Benzylpenicillin is given by injection into a vein or muscle. Two long-acting forms benzathine benzylpenicillin and procaine benzylpenicillin are available for use by injection into a muscle only.

Side effects include diarrhea, seizures, and allergic reactions including anaphylaxis. When used to treat syphilis or Lyme disease a reaction known as Jarisch–Herxheimer may occur. It is not recommended in those with a history of penicillin allergy. Use during pregnancy is generally safe in the penicillin and β-lactam class of medications.