Polio returns after 27 years: All you need to know

A three-month-old Malaysian infant has been diagnosed with polio, the first case reported in the country in 27 years.

The baby boy from Tuaran in Sabah state tested positive for polio after being admitted to a hospital with fever and muscle weakness. He is being treated in an isolation ward and is in stable condition, but still requires assistance to breathe.

What is Polio?

Polio, or poliomyelitis, is a deadly infectious disease caused by the poliovirus, and can cause irreversible paralysis within hours by invading a person’s brain and spinal cord.

It is mainly transmitted by food, water or hands contaminated with human faeces containing the virus. The virus spreads rapidly among children, especially in unsanitary conditions and underdeveloped regions.

Malaysia was declared polio-free in 2000, after reporting its last known case of the disease in 1992. Its resurgence comes just months after the Philippines reported its first cases of polio since 1993 in September.

Tests showed the child was infected with a polio strain that shared genetic links with the virus detected in the recent outbreak in Philippines.

The child in the recent case was confirmed to be infected with VDPV1 which is classified as a circulating vaccine-derived poliovirus (cVDPV) type 1. The cVDPV originates from a poliovirus that has been weakened by the orally-administered polio vaccine.

The weakened virus has been excreted from the body through the faeces. However, in unsanitary environments, the virus can infect others who have not been immunised. There is no cure for polio but spread of the disease can be prevented with polio immunisation.

Why is vaccination important?

Vaccines are biological preparations made from bacteria and viruses known to cause severe and contagious diseases. A portion or the whole of the microorganism known as an “antigen” is usually weakened or killed before it is made into a vaccine.

Once the antigen enters the human body, it will cause an immunological response which results in the formation and the release of antibodies into the bloodstream. The antibodies produced by our body will then work to fight off and neutralise the antigen.

Besides the antigen, a vaccine also contains other components in its formulation such as adjuvants, stabilisers and preservatives, all of which have been added to ensure the quality and safety of vaccines.

A vaccine shot generates antibodies and memory cells which can remain in the body for years. Antibodies neutralise and destroy the invading bacteria or virus while memory cells act as reminders to stimulate an immune response if the body is exposed to the same virus again in the future, resulting in the prevention of dangerous diseases.

The main issue that lead to the new polio case is the low immunisation rates in the region.

Investigations in the area where the baby lived showed 23 of 199 children between the ages of two and 15 years had not received the polio vaccine. Vaccination rates needed to be above 95 percent to prevent infection. The longer the virus spreads in the community, it will undergo genetic mutation until it once again becomes an active virus.

The success in eradicating the disease in the year 2000 was due to prevention efforts through the polio vaccination which was introduced in the National Immunisation Programme in 1972. The programme was made even more effective when the vaccine was changed from being administered orally to being administered through injection.

In the wake of the recent case the parents of the children have agreed to have them vaccinated. Vaccination activities will be continued in the area of and will be expanded to other risk areas

The authorities have also stepped up monitoring of acute flaccid paralysis (AFP) cases. A clinical syndrome which is characterised by weakness of the muscles of respiration and swallowing, a common sign of acute polio. As many as 646 people have been checked and symptoms of AFP have not been detected.

It is currently not compulsory for Malaysian children to be vaccinated before admission to school as it is up to each school to conduct further verification of each student’s immunisation status. The Malaysian government is currently studying to make immunisation vaccination compulsory.