Poliomyelitis

脊髓灰质炎

Evidence-backed information EN 5/7 applicable sections · ZH 5/7 applicable sections Updated Oct 23, 2026

Poliomyelitis is a highly infectious viral disease that has seen a greater than 99% reduction in global cases since 1988 through the Global Polio Eradication Initiative ^[1]^[2]^[3]. Wild poliovirus type 1 remains endemic in two countries as of recent reporting, while types 2 and 3 have been eradicated ^[3]. The disease largely affects children under five but can occur in any unvaccinated person, and it can only be prevented rather than cured ^[1]^[3].

Read the full clinical and epidemiological profile 6

Definition

Poliomyelitis is a highly infectious viral disease caused by poliovirus that invades the nervous system and can produce paralysis within hours ^[1]^[3]. The virus enters through the mouth, multiplies in the intestine, and may subsequently attack the nervous system ^[3].

Clinical features

Initial manifestations include fever, fatigue, headache, vomiting, neck stiffness, and limb pain, typically lasting 2–10 days ^[1]^[3]. Approximately one in 200 infections results in irreversible paralysis, usually of the legs, and among those paralyzed 5–10% die if breathing muscles are immobilized ^[1]^[3]. Up to 90% of infected individuals show no or mild symptoms and the illness goes unrecognized ^[3].

Epidemiology

Global incidence of polio has fallen by over 99% since 1988, from an estimated 350,000 cases across more than 125 endemic countries to a small number of cases and two remaining endemic countries ^[1]^[2]^[3]. Wild poliovirus type 2 was eradicated in 1999 and type 3 in 2020, with type 1 persisting in Pakistan and Afghanistan as of 2022 ^[3]. Regional certification of polio-free status has been achieved for the Americas (1994), Western Pacific (2000), Europe (2002), and South-East Asia (2014) ^[1].

Transmission

The virus spreads person-to-person principally via the faecal-oral route and less often through common vehicles such as contaminated water or food ^[1]^[3]. It multiplies in the intestine after entering through the mouth and can then invade the nervous system ^[3]. Importation into polio-free areas can lead to rapid spread among unimmunized populations ^[2].

Prevention

Polio can only be prevented, as no cure exists, and vaccination given multiple times confers lifelong protection in children ^[1]^[2]. Two safe and effective vaccines are available, oral polio vaccine and inactivated polio vaccine, used in varying combinations based on local epidemiological and programmatic contexts ^[1]. Eradication strategies prioritize immunization and disease surveillance, particularly in affected or high-risk countries ^[1].

References

1 World Health Organization. Poliomyelitis [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/news-room/fact-sheets/detail/poliomyelitis
2 World Health Organization. Poliomyelitis [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/news-room/questions-and-answers/item/poliomyelitis
3 World Health Organization. Poliomyelitis (polio) [Internet]. cited 23 Oct 2026. Available from: https://www.who.int/health-topics/poliomyelitis