[1] The disease was first recognized as a distinct condition by the English physician Michael Underwood in 1789,[1][7] and the virus that causes it was first identified in 1909 by the Austrian immunologist Karl Landsteiner.

[16][17][18] About one to five in 1,000 cases progress to paralytic disease, in which the muscles become weak, floppy and poorly controlled, and, finally, completely paralyzed; this condition is known as acute flaccid paralysis.

In communities with low vaccine coverage, this weakened virus may continue to circulate and, over time may mutate and revert to a virulent form.

[42] The mechanisms by which poliovirus spreads to the CNS are poorly understood, but it appears to be primarily a chance event – largely independent of the age, gender, or socioeconomic position of the individual.

This leads to the development of paralytic poliomyelitis, the various forms of which (spinal, bulbar, and bulbospinal) vary only with the amount of neuronal damage and inflammation that occurs, and the region of the CNS affected.

Poliovirus samples are further analysed using reverse transcription polymerase chain reaction (RT-PCR) or genomic sequencing to determine the serotype (i.e., 1, 2, or 3), and whether the virus is a wild or vaccine-derived strain.

The results of a large clinical trial were promising; the gamma globulin was shown to be about 80 percent effective in preventing the development of paralytic poliomyelitis.

[53] Due to the limited supply of blood plasma gamma globulin was later deemed impractical for widespread use and the medical community focused on the development of a polio vaccine.

[57] The Salk vaccine is based on poliovirus grown in a type of monkey kidney tissue culture (vero cell line), which is chemically inactivated with formalin.

[61] OPV efficiently blocks person-to-person transmission of wild poliovirus by oral–oral and fecal–oral routes, thereby protecting both individual vaccine recipients and the wider community.

Supportive measures include antibiotics to prevent infections in weakened muscles, analgesics for pain, moderate exercise and a nutritious diet.

Historically, a noninvasive, negative-pressure ventilator, more commonly called an iron lung, was used to artificially maintain respiration during an acute polio infection until a person could breathe independently (generally about one to two weeks).

[71] The neurophysiological processes involved in recovery following acute paralytic poliomyelitis are quite effective; muscles are able to retain normal strength even if half the original motor neurons have been lost.

Extended use of braces or wheelchairs may cause compression neuropathy, as well as a loss of proper function of the veins in the legs, due to pooling of blood in paralyzed lower limbs.

[91] With improvements in sanitation and hygiene during the 19th century, the general level of herd immunity in the population declined; this provided circumstances where epidemics of polio became frequent.

In addition, environmental and wastewater samples are tested for the presence of poliovirus - this is an effective method of detecting circulating virus which has not given rise to severe symptoms.

[115] During 2011, the CIA ran a fake hepatitis vaccination clinic in Abbottabad, Pakistan, in an attempt to locate Osama bin Laden.

[138] On 27 March 2014, the WHO announced the eradication of poliomyelitis in the South-East Asia Region, which includes eleven countries: Bangladesh, Bhutan, North Korea, India, Indonesia, Maldives, Myanmar, Nepal, Sri Lanka, Thailand and Timor-Leste.

Doctors and international public health agencies report more than 90 cases of polio in Syria, with fears of contagion in rebel areas from lack of sanitation and safe-water services.

[145] In 2024, the Gaza Health Ministry reported that several children have shown symptoms consistent with polio, with laboratory tests confirming that a 10-month-old child is infected with the virus.

[147] United Nations Secretary-General António Guterres urged for a weeklong cease-fire in Gaza to facilitate vaccinations and prevent a potential polio outbreak, emphasizing the risk faced by many children.

[154] Africa was declared free of wild polio in August 2020, although cases of circulating vaccine-derived poliovirus type 2 continue to appear in several countries.

[156][157] The effects of polio have been known since prehistory; Egyptian paintings and carvings depict otherwise healthy people with withered limbs, and young children walking with canes.

[158] The earliest known case of polio is indicated by the remains of a teenage girl discovered in a 4000-year-old burial site in the United Arab Emirates, exhibiting characteristic symptoms of the condition.

In developed countries during the late 19th and early 20th centuries, improvements were made in community sanitation, including better sewage disposal and clean water supplies.

These changes drastically increased the proportion of children and adults at risk of paralytic polio infection, by reducing childhood exposure and immunity to the disease.

Respiratory centers designed to assist the most severe polio patients, first established in 1952 at the Blegdam Hospital of Copenhagen by Danish anesthesiologist Bjørn Ibsen, were the precursors of modern intensive care units (ICU).

)[168] The polio epidemics not only altered the lives of those who survived them, but also brought profound cultural changes, spurring grassroots fund-raising campaigns that would revolutionize medical philanthropy, and giving rise to the modern field of rehabilitation therapy.

[177] The following countries have been considered polio-free, but not confirmed as of April 2024: Somalia, Djibouti, Sudan, Egypt, Libya, Tunisia, Morocco, Palestine, Lebanon, Syria, Jordan, Saudi Arabia, Bahrain, Qatar, Oman, Yemen, the UAE, Iraq, Kuwait, and Iran.

[182] The retention of live poliovirus samples in laboratories and vaccine manufacturing facilities (which carry a risk of escape of the virus) should progressively be reduced.