Poliomyelitis

Poliomyelitis, commonly known as polio, is an acute intestinal infectious disease caused by infection with the poliovirus. It is also referred to as "infantile paralysis", posing a serious threat to the health of children.

The sources of infection include patients, those with latent infections, and virus carriers, with latent infections and individuals with mild paralytic symptoms being the primary sources of transmission. The main mode of transmission is through the digestive tract, but in the early stages of the disease, it can also spread through respiratory droplets via the oral-oral route. The general population is susceptible, and infection can lead to long-lasting immunity.

The incubation period is typically 3-35 days, with an average of 5-14 days. Polio infection can be categorized as asymptomatic (latent infection), abortive (mild), non-paralytic, and paralytic. Latent infections account for 90 to 95 percent of all infections, abortive cases represent about 4 to 8 percent, and they may exhibit upper respiratory symptoms, gastrointestinal symptoms, and flu-like symptoms.

Non-paralytic cases, compared to abortive cases, may show more severe systemic symptoms, including signs of meningeal irritation. Only 1-2 percent of infected individuals develop muscle paralysis, and typical polio cases refer to those with paralysis, usually asymmetric and without sensory impairment, especially in the limbs (particularly the lower limbs).

Polio is a vaccine-preventable disease, and vaccination with the polio vaccine is effective in preventing polio. The national immunization program includes both inactivated polio vaccine and attenuated live polio vaccine. China achieved the goal of polio eradication in the year 2000. In addition to vaccination, conducting high-quality surveillance of acute flaccid paralysis cases, responding promptly to wild poliovirus and vaccine-derived poliovirus cases, and taking measures to maintain the nation's polio-free status are essential in ongoing efforts against polio.