[Biology Class Notes] on What is Polio? Pdf for Exam

Polio Symptoms

Polio is called poliomyelitis which is a type of a highly contagious disease and is caused by a virus which attacks the human nervous system. Children that are younger than 5 years of age are more prone to contract the virus than the children of any other age group. According to the World Health Organization, 1 in every 200 polio infections would result in the permanent paralysis. The virus is transmitted through person-to-person and is spread mainly through the faecal-oral route or, less likely, by a common vehicle, for example, contaminated water or food. It then multiplies in the intestine from where it could invade the nervous system and result in paralysis. Today we will learn about what is polio, the polio symptoms, what causes polio, and types of polio in detail. 

Poliomyelitis Definition

The polio definition is as follows:

Polio also is called as poliomyelitis. It is a type of a viral disease which destroys the nerve cells that are present in the spinal cord leading to paralysis or muscle weakness to some of the parts of the body. It is a highly contagious disease which affects the nervous system and is caused by the poliovirus called Picornaviridae.

Polio Causes

Let us learn about the poliomyelitis causes in detail.

Since it is a highly contagious virus, polio transmits by the contact with the infected faeces. Objects such as toys which have come near infected faeces may also transmit the virus. Sometimes it can transmit via a sneeze or cough since the virus lives in the throat and the intestines. This is, however, less common.

People that are living in the areas with limited access to the running water or flush toilets often tend to contract polio from drinking water which is contaminated by the infected human waste. In fact, the virus is so contagious that anybody living with a person who has the virus can easily catch it too.

Pregnant women and people having weakened immune systems, like those who are HIV-positive and younger children are most susceptible to the poliovirus.

In case you have not been vaccinated, you may increase your risk of contracting the poliovirus if you:

1. travel to the area which has had a recent polio outbreak

2. take care of or are living with someone who is infected with polio

3. are handling a laboratory specimen of the virus

4. have the tonsils removed

5. have extreme stress or are undergoing a strenuous activity after the exposure to the virus

Types of Polio

There are three different types of polio infections:

1. Subclinical: This type of polio does not experience any kind of symptoms since this does not affect the central nervous system including the brain and the spinal cord. 95 per cent of the total polio cases identified is usually subclinical.

2. Non-paralytic: This type of polio affects the central nervous system, however, does not result in paralysis.

3. Paralytic: This is the most serious and the rarest form of polio since it results in total or partial paralysis in the patient. There are three types of paralytic polio:

• Spinal Polio: affects the spine.

• Bulbar Polio: affects the brain stem.

• Bulbospinal Polio: affects both the spine and the brainstem.

Signs and Symptoms of Poliomyelitis

Let us learn about what are the symptoms of polio. The polio signs and symptoms include the following

It’s estimated that a total of 95 to 99 per cent of the people that contract poliovirus are asymptomatic. This is referred to as subclinical polio. Even without the symptoms, the people infected with the poliovirus may still spread the virus and cause an infection in others.

1. Non-paralytic Polio

The signs and symptoms of the non-paralytic polio may last from 1 to 10 days. These signs and symptoms are flu-like and include:

1. Fever

2. Headache 

3. Vomiting

4. Fatigue

5. Sore throat

6. Meningitis

The non-paralytic polio is also called abortive polio.

2. Paralytic Polio

Around 1 per cent of the total polio cases may develop into the paralytic polio. Paralytic polio leads to the paralysis in the brainstem (bulbar polio), spinal cord (spinal polio), or both (bulbospinal polio).

The initial symptoms are quite similar to the non-paralytic polio. However, after a week, more severe symptoms start to appear. These include:

1. Loss of the reflexes

2. Loose and floppy limbs, often on one side of the body

3. Severe muscle pain and spasms

4. A sudden paralysis, which can be temporary or permanent

5. Deformed limbs, especially the hips, feet, and ankles

It is rare for the full paralysis to develop. Less than 1 per cent of all the polio cases would result in a permanent paralysis. In 5 to 10 per cent of the polio paralysis cases, the virus attacks the muscles which help you to breathe and eventually cause death.

3. Post-polio Syndrome

It is possible for polio to return even if you have recovered. This can generally occur after 15 to 40 years. The common symptoms of post-polio syndrome or PPS are:

1. Continuous muscle and joint weakness

2. Easily exhausted or fatigued

3. Muscle pain which gets worse

4. Muscle wasting also known as muscle atrophy

5. Sleep apnea, or any sleep-related breathing problems

6. Trouble in breathing and swallowing

7. Lower tolerance of colder temperatures

8. A new onset of weakness in the previously uninvolved muscles

9. Trouble related to the concentration and memory

10. Depression

These were the different signs of polio that you must know about.