4.3.2 Mode of transmission and clinical manifestation of polio
Polioviruses are transmitted when people drink water or eat food contaminated by faeces (or stools) which carry the virus (faeco-oral transmission). However, most children infected by polioviruses never feel ill. Less than 5% of those infected may have general flu-like symptoms such as fever, loose stools, sore throat, headache, or stomach ache. Most children who get a poliovirus infection without symptoms develop immunity and have lifelong protection against polio. A few children may develop a kind of paralysis called acute flaccid paralysis (AFP), which is characterised by acute (rapidly developing, severe) loss of movement or weakness of the legs, arms or hands.
Paralytic polio begins with mild symptoms and fever, followed by severe muscle pain and paralysis, which usually develops during the first week of illness. Patients may lose the use of one or both arms or legs. Some patients may not be able to breathe because of the paralysis of respiratory muscles in the chest, which can lead to death. Some patients who develop paralysis due to polio recover the ability to move the affected limbs to some degree over time, but the degree of recovery varies greatly from person to person. A diagnosis of polio is confirmed by laboratory testing of stool samples.