As early as 1580 BCE, poliomyelitis—a viral disease that has afflicted people for centuries—was first reported. The Greek terms “polios,” meaning grey, and “myelon,” referring to the spinal cord, are the source of the disease’s name, highlighting its attack on the central nervous system. Children under five are most commonly affected by polio, which can cause irreversible paralysis in extreme cases. When polio was at its worst in the early to mid-1900s, hundreds of people died each year from the disease, and it was widely disfiguring.
Transmission and Causes
Polio is mostly spread by person-to-person contact through the fecal-oral route, in addition to contaminated food and drink. The virus grows in the colon and can enter the nervous system, where it kills nerve cells, resulting in paralysis.
Primary Means of Transmission:
- Direct contact with an infected person’s excrement (often seen in unsanitary locations)
- Tainted food and water
- Through respiratory droplets from sneezes or coughs, though less frequently
The virus may incubate for three to thirty-five days. About 90% of cases are asymptomatic or produce mild flu-like symptoms. However, the virus can occasionally enter the central nervous system, leading to more serious neurological symptoms.
Polio Types and Symptoms
Polio presents in various forms, with differing degrees of severity:
1. Asymptomatic Polio:
In 90% of cases, those infected with the virus show no symptoms.
2. Non-Paralytic Polio:
This form manifests with flu-like symptoms, including headache, fever, fatigue, and stiffness in the back and neck. Symptoms usually persist for one to ten days.
3. Paralytic Polio:
In less than 1% of cases, polio results in paralysis. The virus reaches the central nervous system, targeting motor neurons in the brainstem and spinal cord. Paralysis, which is often irreversible, can occur within hours. The most affected areas are the legs, breathing muscles, and other body parts.
Diagnosis and Treatment
Polio is diagnosed through stool samples, throat swabs, or (in severe cases) cerebrospinal fluid. There is no cure for polio post-infection; treatment focuses on symptom relief and preventing complications.
Supportive Therapies:
- Medications to ease muscle soreness
- Physical therapy to restore function and prevent deformities
- Mechanical ventilation for those with respiratory paralysis
Survivors of severe polio may experience long-term complications, such as Post-Polio Syndrome (PPS), which leads to fatigue and muscle weakness decades after the initial infection.
Vaccination and Prevention
Vaccination is the most effective way to prevent polio. There are two main types of vaccines used worldwide:
1. Inactivated Poliovirus Vaccine (IPV):
IPV is an injection containing an inactivated or killed virus. It provides immunity without the risk of spreading polio. IPV is predominantly used in countries where polio transmission risk is low.
2. Oral Poliovirus Vaccine (OPV):
OPV is administered orally and contains a weakened form of the virus. OPV has helped eradicate polio in many regions due to its affordability and ease of use. However, in areas with low transmission, there is a small risk of vaccine-derived poliovirus (VDPV), where the weakened virus mutates in populations with insufficient immunity.
Prevention Strategies:
- Maintaining high immunization rates
- Enhancing surveillance to detect potential outbreaks
- Providing clean water, sanitation, and promoting good hygiene practices in vulnerable areas
Global Eradication Efforts
Significant progress in polio eradication has been made since widespread vaccination campaigns began in the mid-20th century. The Global Polio Eradication Initiative (GPEI), launched in 1988, aimed to eliminate polio worldwide. Since then, polio cases have decreased by over 99%, with the disease now endemic only in a few regions.
Successes:
As of 2024, Afghanistan and Pakistan are the only countries where polio remains endemic. The Americas, Europe, and the Western Pacific have been declared polio-free.
Challenges:
- Limited access to vaccines and medical care in conflict-ridden areas
- Vaccine hesitancy in some populations
- The emergence of vaccine-derived poliovirus (VDPV), which occurs when the weakened virus in OPV mutates and regains virulence in areas with low immunity
Despite these challenges, global health organizations remain committed to eradicating polio through sustained immunization campaigns.
Post-Polio Syndrome
Post-Polio Syndrome (PPS) is a late complication experienced by many polio survivors, typically appearing 15–40 years after the initial infection. PPS is characterized by:
- Progressive muscle wasting
- Fatigue
- Joint and muscle pain
Although there is no specific treatment for PPS, management includes physical therapy, pain relief, and lifestyle modifications to improve quality of life.
Conclusion
Polio has had a devastating impact on public health throughout history. However, through international cooperation, robust vaccination campaigns, and persistent global health efforts, eradication is now within reach. While challenges remain, particularly in areas with poor healthcare access, the world is closer than ever to eliminating this crippling disease. Continued vaccination efforts and global collaboration will be crucial in achieving a polio-free world.
