What causes polio disease?

Poliovirus enters through the mouth and multiplies in the digestive tract. It can pass from an infected person through poor hand hygiene, contaminated food, or contaminated water. Some infections cause no clear symptoms; others cause a mild illness with fever, tiredness, headache, nausea, or muscle discomfort. In a small group of affected people, the virus reaches the nervous system and damages nerve cells that control muscles. This may lead to weakness or paralysis, sometimes affecting breathing or swallowing. The virus is not caused by cold weather, a muscle strain, or a person’s character.

Vaccination is the main way to prevent polio and is included in routine childhood immunisation programmes. Check that children and adults travelling to places where polio transmission occurs have received the vaccines recommended for them. Wash hands carefully after using the toilet and before preparing or eating food; safe water and sanitation also reduce spread. If someone may have been exposed or develops sudden weakness, contact a clinician promptly and explain the travel or contact history. Find more information about [Childhood Immunisation](/treatments/preventive-care-and-vaccination/childhood-immunisation/).

Get urgent medical help for new weakness in an arm or leg, difficulty walking, trouble swallowing, breathing difficulty, or rapidly worsening muscle weakness. Sudden weakness has several possible causes and should not be diagnosed at home. Keep the person away from close contact until a clinician gives advice, use careful hand hygiene, and tell the service about recent travel, vaccination history, and possible exposure.

Ask whether the vaccination record is complete, whether a booster is advised for travel, and which symptoms need immediate assessment. You can also ask how to protect household members if polio is suspected and whether testing or public-health advice is needed.