Poliovirus, the causative agent of the disease poliomyelitis, also known as polio, is a highly infectious virus and mainly infects young children. The disease caused by this virus has been one of the landmark diseases in medical history because of its widespread eruption, causing paralysis, followed by death in severe cases. Though global efforts in vaccination against polio have resulted in reduced polio cases, the presence of poliovirus in certain geographic regions remains a concern. Therefore, it is essential to continue monitoring and conducting various studies.

Here, we elaborate on the key facts regarding poliovirus, its causes, symptoms, and methods of prevention. It also explains how the virus is used for laboratory research to achieve better ways of controlling and treating the viral infection.

Overview of Poliovirus

Poliovirus is an enterovirus belonging to the Picornaviridae family. It is an RNA virus, which means that its genetic material is ribonucleic acid rather than DNA. The virus is transmitted through the fecal-oral route, where it enters the body through contaminated food, water, or direct contact with an infected person. After entering the body, the virus instantly multiplies within the intestines and spreads to the nervous system, causing damage to motor neurons.

There are three strains of wild poliovirus known today, Type 1, Type 2, and Type 3. Type 2 was declared eradicated in 2015 and efforts continue to hunt down the remaining strains. The disease could range from asymptomatic infection to severe paralysis. It has been fortunate that with the introduction of effective vaccines, there has been a drastic cut in the number of polio cases, although isolated outbreaks still occur in some countries.

Top Facts about Poliovirus

1. Poliovirus Nearly Eradicated: Due to massive vaccination campaigns, the virus has been nearly eradicated from most of the world. Today, according to current information, polio is endemic in only two countries: Afghanistan and Pakistan.
2. Polio Vaccination was a Major Medical Breakthrough: The developmental efforts into the polio vaccine led by Dr. Jonas Salk in 1955 and later improved by Dr. Albert Sabin were a time of major breakthroughs in the medical history of preventing millions of deaths and paralysis cases.
3. Polio Caused Global Outbreaks: One of the diseases feared throughout the first half of the 20th century was polio, which could trigger widespread epidemics in some countries of the planet, including the United States and Europe.
4. Not Everyone Infected Shows Symptoms: Statistics reveal that about 72% of those infected with poliovirus will not experience symptoms or signs of the disease. Only a few percent of the infected would eventually suffer from paralysis.
5. The Iron Lung: Before ventilators were available for everyone, patients diagnosed with severe polio-related respiratory complications were placed in an “iron lung,” a machine that helps them breathe.
6. Oral and Injectable Vaccines: There are two types of polio vaccines-the inactivated poliovirus vaccine (IPV), which is injected into the body and the oral poliovirus vaccine(OPV), taken orally. Both vaccines have been pivotal in control of the disease.

Causes 

The primary cause of polio is infection with the poliovirus, which spreads through contaminated water, food, and fecal matter. The virus thrives in unsanitary conditions where there is a lack of proper hygiene and sanitation.

Transmission Routes:

• Fecal-Oral Transmission: It is the most common route of transmission. One gets infected when they consume food or water contaminated with fecal matter that contains the poliovirus. The easy routes of transmission are guaranteed through poor hygiene and a lack of proper sanitation facilities.
• Person-to-Person Contact: The virus is transmitted via droplets or aerosols from the throat. Poliovirus can also be spread through close contact with an infected person, especially if they come into contact with their bodily fluids or stool. 

Individuals living in crowded or unsanitary environments are more likely to be exposed to the infection especially in areas where clean sources of water and appropriate facilities for waste disposal are scarce. The virus predominantly targets children younger than 5 years of age, but adults with full exposure to an infected person can also become infected if they are not vaccinated.

Symptoms 

The symptoms of polio vary according to the extent of infection. Many people infected with the virus are asymptomatic. However some may have mild or severe symptoms.

Asymptomatic Infection:

• Some studies have shown that 72% of people infected with poliovirus are asymptomatic, yet they can still spread the virus to others. These individuals serve as silent carriers of the virus.

Mild Symptoms (Abortive Polio):

• Fever
• Fatigue
• Headache
• Nausea
• Sore throat
• Vomiting

These symptoms typically clear up within a few days, and individuals may never even realize.

Non-Paralytic Polio: In some cases, polio results in flu-like illnesses, including:

• Stiffness in the neck and back
• Pain or tenderness of muscles

These symptoms can last for several days to a few weeks but do not result in paralysis.

Paralytic Polio (The most severe form):

• Weakness or paralysis of arms, legs, or both.
• Respiratory paralysis (the virus impairs the muscles that assist in respiration).
• Loss of reflexes.

In rare cases, paralytic polio can result in permanent disability or even death when the respiratory muscles of the patient get paralyzed.

Prevention and Control Measures 

Prevention of polio is best achieved through vaccination. Vaccines have reduced polio significantly across the entire globe and now is the main approach in a worldwide campaign to eradicate the disease from the face of the earth.

1. Vaccination:

The Inactivated Poliovirus Vaccine (IPV), administered via injection, is widely used in several countries also for routine childhood immunization schemes. It is a killed-virus particle, and provides excellent immunity against polio.

The Oral Poliovirus vaccine (OPV),is an orally administered, weakened virus. The immunity as well as the arrest of further spread due to the shedding in the feces happens but can not be used worldwide because it carries a small risk of vaccine-derived polio.

2. Hygiene and Sanitation:

Improved sanitary conditions, including disposal of sewage and access to clean drinking water, is equally important in preventing the virus transmission. Education on hygiene, including handwashing with soap, is also vital in prevention.

3. Surveillance and Monitoring:

World polio surveillance efforts are being formed to detect new cases of polio and react promptly. They include monitoring outbreaks, collection of stool samples for testing, and identification of areas that require vaccination campaigns.

Uses at MIS Lab

The viruses in the lab are applied in several applications at Microbe Investigations Switzerland (MIS) including testing the effectiveness of disinfectants and antiviral products among many others. 

• BS EN 17914: Quantitative suspension test method for establishing virucidal activity of chemical disinfectants and antiseptics in food, industrial, domestic, and institutional areas.
• EN 14476 Test – Quantitative suspension test for the determination of virucidal activity of disinfection products in the medical area.
• BS EN 16777 – Quantitative Non-porous Surface test without mechanical action for the evaluation of virucidal activity of chemical disinfectants used in the medical area.
• ASTM E1053 : 2011 – Standard to Assess Virucidal Activity of Chemicals Intended for Disinfection of Inanimate and Nonporous environmental surfaces
• JIS L 1922 – Determination of Antiviral Activity of Textile Products
• ISO 21702: 2019 is a proper method for measuring antiviral activity on plastics and other non-porous surfaces of antiviral-treated products against viruses.
• ASTM E1838 – outlines a test method to assess the effectiveness of handwash and hand rub product formulation in eliminating transient viruses from the skin.

Conclusion

Poliovirus remains a critical subject of study despite significant progress toward its eradication. The virus can cause severe illness, including paralysis, and still poses a threat in regions where vaccination coverage is low. Understanding the virus, its symptoms, transmission, and prevention measures is essential for global health efforts. Vaccination, improved sanitation, and rigorous surveillance are the keys to preventing further outbreaks.

For laboratories and manufacturers interested in determining if their products are effective against viruses, Microbe Investigations Switzerland (MIS) provides comprehensive testing services. Contact MIS today and learn how we can serve your needs in viral testing and product validation.