The incubation time (form the first signs and symptoms) ranges from three to 35 days, with a more common span of six to 20 days. This group of RNA viruses colonize the gastrointestinal tract – specifically the oropharynx and the intestine. Poliomyelitis is caused by infection with a member of the genus Enterovirus known as poliovirus (PV). It is characterized by confusion, changes in mental status, headaches, fever, and, less commonly, seizures and spastic paralysis. Įncephalitis, an infection of the brain tissue itself, can occur in rare cases, and is usually restricted to infants. In those who develop paralysis, between 2 and 10 percent die as the paralysis affects the breathing muscles. Depending on the site of paralysis, paralytic poliomyelitis is classified as spinal, bulbar, or bulbospinal. The weakness most often involves the legs, but may less commonly involve the muscles of the head, neck, and diaphragm. About one to five in 1000 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. Most patients with CNS involvement develop nonparalytic aseptic meningitis, with symptoms of headache, neck, back, abdominal and extremity pain, fever, vomiting, stomach pain, lethargy, and irritability. In about 1 percent of infections the virus can migrate from the gastrointestinal tract into the central nervous system (CNS). These symptoms are temporary and full recovery occurs within one or two weeks. In about 25% of cases, the infection produces minor symptoms which may include sore throat and low fever. In most people with a normal immune system, a poliovirus infection is asymptomatic. Adults are more likely to develop symptoms, including severe symptoms, than children. Two basic patterns of polio infection are described: a minor illness which does not involve the central nervous system (CNS), sometimes called abortive poliomyelitis, and a major illness involving the CNS, which may be paralytic or nonparalytic. The term "poliomyelitis" is used to identify the disease caused by any of the three serotypes of poliovirus. Signs and symptoms Outcomes of poliovirus infection in children Outcome There are rare incidences of disease transmission and/or of paralytic polio associated with the attenuated oral vaccine and for this reason the injected vaccine is preferred. Through the use of both types of vaccine, incidence of wild polio has decreased from an estimated 350,000 cases in 1988 to 6 confirmed cases in 2021, confined to just three countries. There are two broad types of polio vaccine an injected vaccine using inactivated poliovirus and an oral vaccine containing attenuated (weakened) live virus. The disease can be prevented by the polio vaccine, with multiple doses required for lifelong protection. Once infected, there is no specific treatment. Following the introduction of polio vaccines in the 1950s polio incidence declined rapidly. Major outbreaks started to occur in the late 19th century in Europe and the United States, and in the 20th century, it became one of the most worrying childhood diseases. The disease was first recognized as a distinct condition by the English physician Michael Underwood in 1789, and the virus that causes it was first identified in 1909 by the Austrian immunologist Karl Landsteiner. Poliomyelitis has existed for thousands of years, with depictions of the disease in ancient art. The disease may be diagnosed by finding the virus in the feces or detecting antibodies against it in the blood. Those who are infected may spread the disease for up to six weeks even if no symptoms are present. poor hygiene, or by ingestion of food or water contaminated by human feces), or via the oral-oral route. It is highly infectious, and is spread from person to person either through fecal-oral transmission (e.g. Years after recovery, post-polio syndrome may occur, with a slow development of muscle weakness similar to that which the person had during the initial infection. A less common symptom is permanent paralysis, and possible death in extreme cases. These symptoms usually pass within one or two weeks. Approximately 70% of cases are asymptomatic, mild symptoms which can occur include sore throat and fever in a proportion of cases more severe symptoms develop such as headache, neck stiffness, and paresthesia. Poliomyelitis, commonly shortened to polio, is an infectious disease caused by the poliovirus. Poliovirus spread by fecal–oral route įinding the virus in the feces or antibodies in the blood Muscle weakness resulting in an inability to move
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