Polio Poliomyelitis

What is Polio?

Polio (poliomyelitis) is an acute highly infectious viral disease which mainly affects young children. It is caused by three types of poliovirus, Types 1, 2, and 3. Poliovirus infection occurs in the gastrointestinal tract and spreads in a minority of cases to the nervous system.

Polio cases have decreased worldwide by over 99 percent since 1988 due to a global effort to eradicate the disease. In countries that report polio cases, roughly 70-80 percent of cases are less than 3 years of age and 80-90 percent of cases are less than 5 years of age.

How do you get Polio?

The virus responsible for polio is transmitted through contaminated food and water and multiplies in the intestine, from where it can invade the nervous system to cause paralysis. Many infected people show no symptoms but do continue to excrete the virus in their feces, potentially transmitting the infection to others.

Susceptibility and Resistance

Susceptibility to infection is universal, however, paralysis occurs in only about 1 percent of infections. Paralysis occurs more frequently in infected, non-immune adults than in non-immunised infants and young children. Type-specific immunity lasts for the patients’ entire lives. Second attacks are rare and result from infection with poliovirus of a different type.

Incubation Period

The incubation period for Polio is 7-14 days.

What are the Symptoms?

Many polio infections show no symptoms at all. When present, initial symptoms of polio include fever, fatigue, headache, vomiting, stiffness in the neck, and pain in the limbs. A small proportion of infections (one in 200) can cause paralysis (often permanent) in only a number of hours. Among those that experience paralysis, 5 to 10 percent die when their breathing muscles become immobilized.

Preventative Measures

There is no cure for polio. It can only be prevented by immunization through a polio vaccine, which is administered multiple times in early childhood.  Keeping childhood vaccinations up to date through booster doses is important before travelling in areas where polio has not been eliminated.  Avoiding contaminated food and water in those areas is important.


There is no known cure or treatment for polio. It can only be prevented through immunisation.


Where Does It Commonly Occur?

Since 1988 there has been a global effort to eliminate this disease through the widespread use of polio vaccination. As a result, in 2013, only three countries in the world continue to report sporadic cases of polio. These countries are Afghanistan, Nigeria, and Pakistan. Occasionally, a case of polio is imported into a country where the disease has been already eliminated, and a few secondary cases may occur. Such cases have occurred in Angola, Niger, Chad, the Democratic Republic of the Congo, and southern Sudan.

Recently, there have been outbreaks of polio in Ethiopia, Somalia and Syria.