poliomyelitis n : an acute viral disease marked by inflammation of nerve cells of the brain stem and spinal cord [syn: polio, infantile paralysis, acute anterior poliomyelitis]
Nounpoliomyelitis (plural: poliomyelitides)
Poliomyelitis, often called polio or infantile paralysis, is an acute viral infectious disease spread from person to person, primarily via the fecal-oral route. The term derives from the Greek polio (πολίός), meaning "grey", myelon (µυελός), referring to the "spinal cord", and -itis, which denotes inflammation. Although around 90% of polio infections have no symptoms at all, affected individuals can exhibit a range of symptoms if the virus enters the blood stream. In fewer than 1% of cases the virus enters the central nervous system, preferentially infecting and destroying motor neurons, leading to muscle weakness and acute flaccid paralysis. Different types of paralysis may occur, depending on the nerves involved. Spinal polio is the most common form, characterized by asymmetric paralysis that most often involves the legs. Bulbar polio leads to weakness of muscles innervated by cranial nerves. Bulbospinal polio is a combination of bulbar and spinal paralysis.
Poliomyelitis was first recognized as a distinct condition by Jakob Heine in 1840. Its causative agent, poliovirus, was identified in 1908 by Karl Landsteiner. Enhanced vaccination efforts led by the World Health Organization, UNICEF and Rotary International could result in global eradication of the disease.
Poliomyelitis is caused by infection with a member of the genus Enterovirus known as poliovirus (PV). This group of RNA viruses prefers to inhabit the gastrointestinal tract. All three are extremely virulent and produce the same disease symptoms. In endemic areas, wild polioviruses can infect virtually the entire human population. It is seasonal in temperate climates, with peak transmission occurring in summer and autumn. Virus particles are excreted in the feces for several weeks following initial infection. a mode especially visible in areas with good sanitation and hygiene. malnutrition, tonsillectomy, physical activity immediately following the onset of paralysis, skeletal muscle injury due to injection of vaccines or therapeutic agents, and pregnancy. Although the virus can cross the placenta during pregnancy, the fetus does not appear to be affected by either maternal infection or polio vaccination. Maternal antibodies also cross the placenta, providing passive immunity that protects the infant from polio infection during the first few months of life.