Variolation

Inoculation is the placement of something to where it will grow or reproduce, and is most commonly used in respect of the introduction of a serum, vaccine, or antigenic substance into the body of a human or animal, especially to produce or boost immunity to a specific disease; but also can be used to refer to the communication of a disease to a living organism by transferring its causative agent into the organism, to implant microorganisms or infectious material into a culture medium such as a brewers vat or a petri dish, to safeguard as if by inoculation, to introduce an idea or attitude into someone's mind, any placement of microorganisms or viruses at a site where infection is possible such as to increase soybeans' nitrogen fixation one can treat soybeans at planting with Rhizobium japonicum inoculant. The verb "to inoculate" is from Middle English "inoculaten", which meant "to graft a scion (a scion is a plant part to be grafted onto another plant); which in turn is from Latin "inoculare", past participle "inoculat-".^[1]^[2]

This article covers variolation, inoculation as a method of purposefully infecting a person with smallpox (Variola) in a controlled manner so as to minimise the severity of the infection and also to induce immunity against further infection. See vaccination for post-variolation methods of safeguarding as if by inoculation by administering weakened or dead pathogens to a healthy person or animal with the intent of conferring immunity against a targeted form of a related disease agent.

Today the terms inoculation, vaccination and immunisation are used more or less interchangeably and popularly refer to the process of artificial induction of immunity against various infectious diseases. The microorganism used in an inoculation is called the inoculant or inoculum.

Origins

The earliest record of inoculation is found in 8th century India, when Madhav wrote the Nidāna, a 79-chapter book which lists diseases along with their causes, symptoms, and complications. He included a special chapter on smallpox (masūrikā) and described the method of inoculation to protect against smallpox.^[3]

Around the same time, it is recorded that the Chinese inoculated their patients by making them snort the powdered scabs of smallpox victims since at least the 10th century. Another method of their inoculation was by scratching the powder into their skin.[3][4]

Importation to the West

The practice was introduced to the west by Lady Mary Wortley Montagu (May 26, 1689-August 21, 1762). Lady Montagu's husband, Edward Wortley Montagu, served as the British ambassador to the Ottoman Empire from 1716 to 1717. She witnessed inoculation being practiced by physicians in Constantinople,^[4] and was greatly impressed:^[5] she had lost a brother to smallpox and bore facial scars from the disease herself. In March 1718 she had the embassy surgeon, Charles Maitland, inoculate her five-year-old son. In 1721, after returning to England, she had her four-year-old daughter inoculated^[6]. She invited friends to see her daughter, including Sir Hans Sloane, the King's physician. Sufficient interest arose that Maitland gained permission to test inoculation at Newgate prison in exchange for their freedom on six prisoners due to be hanged, an experiment which was witnessed by a number of notable doctors.^[7] All survived, and in 1722 the Prince of Wales' daughters received inoculations^[8].

The practice of inoculation slowly spread amongst the royal families of Europe, usually followed by more general adoption amongst the people.

The practice is documented in America as early as 1721, when Zabdiel Boylston, at the urging of Cotton Mather, successfully inoculated two slaves and his own son. Mather, a prominent Boston minister, had heard a description of the African practice of inoculation from his Sudanese slave, Onesimus, in 1706, but had been previously unable to convince local physicians to attempt the procedure.^[9] Following this initial success, Boylston began performing inoculations throughout Boston, despite much controversy and at least one attempt upon his life. The effectiveness of the procedure was proven when, of the nearly three hundred people Boylston inoculated during the outbreak, only six died, whereas the mortality rate among those who contracted the disease naturally was one in six.^[10]

In France considerable opposition arose to the introduction of inoculation. Voltaire, in his Lettres Philosophiques, wrote a criticism of his countrymen for being opposed to inoculation and having so little regard for the welfare of their children, concluding that "had inoculation been practised in France it would have saved the lives of thousands.".^[12]

Inoculation grew in popularity in Europe through the 18th century. Given the high prevalence and often severe consequences of smallpox in Europe in the 18th century (according to Voltaire, there was a 60% incidence of first infection, a 20% mortality rate, and a 20% incidence of severe scarring),^[13] many parents felt that the benefits of inoculation outweighted the risks and so inoculated their children.^[14]

Mechanism

Two forms of the disease of Smallpox were recognised, now known to be due to two strains of the Variola virus. Those contracting Variola Minor had a greatly reduced risk of death — 1-2% — compared to those contracting Variola Major with 20% mortality. Infection via inhaled viral particles in droplets spread the infection more widely than the deliberate infection through a small skin wound. The smaller, localised infection is adequate to stimulate the immune system to produce specific immunity to the virus, while requiring more generations of the virus to reach levels of infection likely to kill the patient. The rising immunity terminates the infection. So the twofold effect is to ensure the less fatal form of the disease is the one caught, and to give the immune system the best start possible in combating it.

Inoculation in the East was historically performed by blowing smallpox crusts into the nostril. In Britain, Europe and the American Colonies the preferred method was rubbing material from a smallpox pustule from a selected mild case (Variola minor) into a scratch between the thumb and forefinger. [5] This would generally be performed when an individual was in normal good health, and thus at peak resistance. The recipient would develop smallpox; however, due to being introduced through the skin rather than the lungs, and possibly because of the inoculated individual's preexisting state of good health, the small inoculum, and the single point of initial infection, the resulting case of smallpox was generally milder than the naturally-occurring form, produced far less facial scarring, and had a far lower mortality rate. As with survivors of the natural disease, the inoculated individual was subsequently immune to re-infection.

Supplanted by vaccination

In 1796, Edward Jenner introduced the far safer method of inoculation with the cowpox virus, a non-fatal virus that also induced immunity to smallpox. This led to smallpox inoculation falling into disuse and eventually being banned in England in 1840.

Contents

Origins

Importation to the West

Mechanism

Supplanted by vaccination

See also

References