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How does poliovirus spread from one person to another?

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Polio vaccine — polio A health care worker giving a polio vaccine to a child in Katsina state, Nigeria, 2014.

The poliovirus is highly contagious and spreads primarily through the fecal-oral route. This occurs when the virus is ingested via food, water, or hands that have been contaminated with the feces of an infected person.123

Additionally, the virus can spread through:
* Close personal contact: Touching contaminated surfaces and subsequently touching the mouth.2
* Respiratory droplets: Ingestion of droplets or saliva expelled from the throat of an infected individual, particularly during the early stages of infection.132

Because infected individuals can shed the virus from their throats for a week and in their feces for a month or more—even if they show no symptoms—the virus can spread easily in environments with poor sanitation or low vaccination coverage. Once ingested, the virus multiplies in the lymph nodes of the intestinal tract and may spread through the bloodstream.123