poliomyelitis

an infectious disease caused by a VIRUS that attacks the CENTRAL NERVOUS SYSTEM . The virus is taken in by mouth, passes through the ALIMENTARY CANAL and is excreted with the FAECES . The hands may be contaminated, leading to further spread. The INCUBATION period is seven to 12 days, and there are several types of condition, depending on the severity of the attack. In some cases the symptoms resemble a stomach upset or INFLUENZA ; in others there is, in addition, some stiffness of muscles. paralytic poliomyelitis is less common, resulting in muscle weakness and PARALYSIS , while the most serious cases involve breathing, when the DIAPHRAGM and related muscles are affected (bulbar poliomyelitis). IMMUNIZATION is highly effective, and the disease has almost been eradicated in most countries. However, booster doses are advisable when visiting countries with a high incidence of the disease.