Infectious diseases

Polio

( Updated at 11/05/2023 )

4 minutes of reading

What is polio?

Poliomyelitis is an infectious disease caused by poliovirus, a very contagious virus of the enterovirus group that spreads through oral secretions and feces.

This disease may not give symptoms, but in some cases it can be extremely disabling or even deadly, since invading the nervous system it can cause paralysis of the respiratory muscles.

Are there any cases of polio in Portugal?

At the moment, there are no cases of poliomyelitis in Portugal and the last case of the disease in the country was recorded in 1986. Since 2002, the European region has been considered polio-free.

Polio cases have declined by more than 99 percent since 1988. That is, from about 350 thousand cases in more than 125 endemic countries, it went to 175 cases reported in 2019, worldwide.

The introduction of vaccines and improved sanitation have contributed to this reduction.

What are the symptoms of polio?

People infected with poliovirus are often asymptomatic (about 90 to 95% of cases), meaning they have no symptoms. In cases where symptoms are reported, they may be similar to those of other viral diseases and present:

fever
fatigue
headache
sore throat
Vomiting
stiffness in the neck
Pain in the muscles

What is the incubation period of the disease?

The incubation period is 3 to 6 days. When there is paralysis, it usually occurs 7 to 21 days after infection.

How is polio diagnosed?

The diagnosis of poliomyelitis includes the patient's complete medical history, including history of recent travel and vaccination history with symptom screening and may include tests of stool, blood, urine, cerebrospinal fluid for the virus.

How is polio transmitted?

Poliovirus, the virus that causes polio, lodges in the throat and intestines and is shed through faeces and respiratory droplets. Therefore, it can be transmitted from person-to-person via fecal-oral, by:

Direct contact with:
- faeces from an infected person
- contaminated pharyngeal droplets and secretions, especially by coughing, sneezing
- by airway, through the inhalation of droplets
indirect contact with contaminated water, food or objects

Who is most at risk of getting polio?

The main risk group for this disease is children.

What are the complications of this disease?

If poliovirus spreads in the bloodstream, it can lead to serious complications, especially in the nervous system, affecting the brain and spinal cord, such as:

Paralysis: This is the most serious complication and is characterized by the inability to move parts of the body, and is potentially deadly if it hits the muscles that help you breathe
Meningitis: Inflammation of the meninges, membranes that protect the brain and spinal cord, is the most common complication
Post-polio syndrome: signs and symptoms of the disease in the long term

In more severe cases, it can even cause death.

What is post-polio syndrome?

Post-polio syndrome is a condition that affects between 20 and 50% of polio survivors. This syndrome is characterized by a set of signs and symptoms that manifest in the long term, on average, 35 years after infection, and may include:

progressive muscle weakness, with muscle flaccidity and atrophy of the muscles
mental and physical fatigue
pain associated with joint deformities

Is there a vaccine to prevent the disease?

yes. The vaccine is included in the National Vaccination Program. Vaccination is the best preventive measure to reduce the risk of polio virus circulating worldwide and the only one that allows the disease to be eradicated from the planet.

Portugal started the National Polio Eradication Program in 1995 according to the rules instituted by the World Health Organization, but the elimination of poliomyelitis in Portugal was achieved through a vaccination campaign in 1965/1966 and by the application of the National Vaccination Program from 1965 to the present day.