Health Tips

Image credit: https://phil.cdc.gov/Details.aspx?pid=5578

What you see here is a young girl experiencing deformity in her right leg as a result of being infected by the poliovirus. Poliovirus belongs to the genus Enterovirus and it is what caused polio. Polio is also known as poliomyelitis, is a disabling and life-threatening infectious disease.

If you have read some historical texts, polio is likely to remain in your mind as a disease in a distant past. Does it still exist in today’s world?

Yes, polio does still exist -- even in Malaysia

Image credit: Bahagian Kawalan Penyakit, KKM

Although polio cases have decreased by over 99% since 1988, from an estimated more than 350 000 cases to 22 reported cases in 2017. This reduction is the result of the global effort to eradicate the disease. Today, only 3 countries in the world have never stopped transmission of polio, which are Pakistan, Afghanistan and Nigeria. 

Unfortunately, Malaysia has also seen 4 cases of confirmed polio incidents in Sabah since year 2019, all of which affected children who aged below 12 years old. The authority has quickly responded by initiating the Polio Immunisation campaign in June, although the effort has been halted due to the high COVID-19 cases that followed suit. 

How polio affects people

Image credit: CDC

The poliovirus can be spread from one person to another. Most people who get infected with poliovirus (about 72 out of 100) will not have any visible symptoms. About 1 out of 4 people with poliovirus infection will have flu-like symptoms (which share an uncanny similarity with COVID-19 and other viral infections) that may include:

• Sore throat

• Fever

• Tiredness

• Nausea

• Headache

• Stomach pain

These symptoms usually last 2 to 5 days, then go away on their own. 

Among a smaller proportion of people, the virus can infect a person’s nervous system, i.e. brain and spinal cord, causing debilitating symptoms, such as:

• Tingling feeling/ feeling of pins and needles in the legs (paresthesia)

• Meningitis, which is the inflammation of the membranes that cover the brain and spinal cord. In the case of polio, the inflammation is caused by the infection of poliovirus. 

• Paralysis. In a clinical setting, such a symptom is known as acute flaccid paralysis (AFP). While there can be many reasons for the occurence of AFP, healthcare professionals must rule out the cause of polio whenever they encounter patients with unexplained AFP. This is to ensure that any importation of poliovirus is quickly identified and investigated. 

Image credit: https://africa-health.com/news/rotary-releases-us8-1-million-to-end-polio-in-nigeria/

Paralysis is the most severe consequence among them all, because it can lead to permanent disability and death. Between 2 and 10 out of 100 people who have paralysis from polio virus infection die, because the virus affects the muscles that help them breathe.

Even children who seem to fully recover can develop new muscle pain, weakness, or paralysis as adults, 15 to 40 years later. This is called post-polio syndrome (PPS). PPS is not infectious, but it can make it extremely difficult for the person to go on with their normal lives.

How does polio spread?

Poliovirus is spread through person-to-person contact and it mainly lives in a person’s throat and intestines. Poliovirus only infects people. It enters the body through the mouth and spreads through:

• Contact with the feces (poop) of an infected person.

• Droplets from a sneeze or cough of an infected person (less common).

You can get infected with poliovirus if:

• You have feces on your hands, and you touch your mouth.

• You put in your mouth objects like toys that are contaminated with feces.

An infected person may spread the virus to others immediately before and up to 2 weeks after symptoms appear.

• The virus can live in an infected person’s feces for many weeks. It can contaminate food and water in unsanitary conditions.

• People who don’t have symptoms can still pass the virus to others and make them sick.

Image credit:https://www.thailandmedical.news/news/polio-outbreak-in-philippines

Polio is extremely infectious, even more so than flu and the infamous COVID-19 virus. Scientists use the indicator R₀ (pronounced as “R naught”), or basic reproduction number, to communicate how infectious a virus is. R₀ tells you the average number of people who will contract a contagious disease from one person with that disease. To grasp how infectious polio is, here are the comparisons of its R₀ .

Source: https://sph.umich.edu/pursuit/2020posts/how-scientists-quantify-outbreaks.html

To put into simpler terms, a person with polio can potentially transmit the poliovirus to 5 to 7 persons; in contrast to 2-4 persons for COVID-19 and 1 to 2 persons for the flu.

This R₀ is not permanent, however. With good prevention strategies and vaccinations, R₀ can be reduced to below 1, which the disease is expected to decline and die out. Likewise, if the vaccination rate in a population is reduced, R₀ can even increase and affect more people in the population!

Polio can’t be cured, but it can be prevented through vaccination

Image credit: https://www.unicef.org/immunization/polio

Although there’s no cure for polio at the moment, it is one of the few diseases that can be eradicated completely because:

• polio only affects humans, and there is no animal that can be infected by polio

• an effective and inexpensive vaccine for polio exists, it’s called inactivated polio vaccine (IPV) in Malaysia

• immunity against polio is life-long

• the virus can only survive for a very short time in the environment

In Malaysia, an inactivated polio vaccination (IPV) is compulsory for every child. Children shall receive four doses of polio vaccine in total, which occur at ages of 2 months, 3 months, 5 months and 18 months respectively. They are given as injections in the leg or arm. Four doses of free vaccination given by the Ministry of Health Malaysia can protect your child for life, what a bargain! 

Polio is an unnecessary suffering 

For something like polio, there is really no reason that any child should suffer from its consequences due to failure of vaccination -- whether it is because of baseless anti-vaccine attitude or lack of access to vaccination service. If anything that the present global COVID-19 pandemic has taught us is that vaccination is a modern science victory that everyone should champion, because prevention is always better than cure.

Image credit: https://www.bernama.com/en/features/news.php?id=1797842

References:

1. CDC - What is Polio. https://www.cdc.gov/polio/what-is-polio/index.htm

2. Immunise4Life - Children. https://www.immunise4life.my/children/

Written By

Ms Joyce Toh

Reviewed By

Doc2us Medical Board