Understanding Polio: An In-Depth Overview
Polio, or poliomyelitis, is an extremely contagious illness that was formerly a globally widespread cause for concern. It is caused by the poliovirus and affects mostly children under five years of age and, in severe infections, can result in lifelong paralysis or death. Despite widespread health campaigns that have brought it under some control, polio remains an issue of medical and health concern.
This guide is intended to describe what polio is, how it spreads, symptoms, methods of treatment, and long-standing attempts to eradicate it completely.
What causes Polio?
Polio is caused by the poliovirus, an enterovirus. It was first discovered in 1909. Transmission occurs mainly through human-to-human contact, contaminated food or water — particularly in poorly sanitized environments. Knowing how polio spreads is vital for outbreak prevention, especially in areas with struggling health systems.
A Brief History of Polio
While polio had been present for centuries, it was only in the 19th and 20th centuries that it was a significant concern for public health. In 1916, a major epidemic occurred in New York City that killed more than 2,000 individuals, leading to widespread panic. Their most severe epidemic in America was in 1952 with almost 58,000 reported cases, inclusive of over 3,000 fatalities and over 21,000 cases of paralysis.
These statistics highlight just how devastating an effect polio had before there was a vaccine.
Types of Poliovirus
There are three types of poliovirus: Type 1, Type 2, and Type 3. Though all can lead to paralysis, Type 1 is most frequently encountered. Global health bodies labeled Type 2 as eradicated in 2015 and Type 3 in 2019. Now only wild poliovirus Type 1 is still endemic, mostly in Afghanistan and Pakistan.
Symptoms and effects on the nervous system
Polio does not produce any symptoms in many people who have it. Some people get mild symptoms that resemble the flu — such as sore throat, headache, fever, and exhaustion. But in 1 of every 200 infections, the virus attacks the central nervous system, causing muscle weakness and paralysis. In severe cases, it weakens the breathing muscles, necessitating mechanical ventilation.
It is permanent neurological damage that can result from such an injury. Thousands of patients in the mid-20th century were using "iron lungs" – massive machines that breathed for them – due to paralysis caused by polio.
Treatment
There is no cure for polio today. Symptomatic treatment is centered around physical therapy, the alleviation of pain, and orthopedic care. Post-polio syndrome, a syndrome that develops many years after the infection, with symptoms of weakness, joint ache, and exhaustion, occurs in some survivors.
Knowledge of these long-term consequences of polio highlights the significance of prevention through immunization.
Polio Vaccine: A Worldwide Milestone
One of medicine's greatest milestones was achieved in 1955, with Dr. Jonas Salk's introduction of the inactivated polio vaccine (IPV). Dr. Albert Sabin later developed an oral polio vaccine (OPV) in 1961; this soon found favor with many regions in the world because it was easy to administer, as well as being effective.
Both of these vaccines have had a significant role to play in the dramatic reduction of polio patients globally. Polio, at the inception of the Global Polio Eradication Initiative (GPEI) in 1988, was still endemic in 125 countries, with over 350,000 cases reported each year. By 2024, that number had reduced to a handful of cases around the world — a testament to the success of vaccines like the polio vaccine.
Why Polio Persists in Some Countries
Continuing Global Eradication Efforts
Eradicating polio has necessitated one of the largest health collaborations in history. Global health organizations such as the World Health Organization (WHO), UNICEF, and Rotary International have spearheaded massive vaccination campaigns that have reached over 2.5 billion children since 1988. Support in terms of money, education, and ongoing surveillance are all vital pillars of these campaigns.
While the pandemic caused by COVID-19 interrupted routine immunizations in 2020, worldwide partners restarted their work with increased urgency.
Is Polio a Threat Now?
Despite their extremely low levels now, polio remains a threat, especially in regions with falling vaccination rates. One such example was a vaccine-derived case of polio that was confirmed in New York in 2022, reminding everyone that even countries that are considered free of polio are not immune if their immunization levels fall. Ongoing vigilance, vaccination, and surveillance will be required to avoid a rise.
Polio is no longer the global threat that it was before, but the battle against it is not finished. With a mix of science, international cooperation, and health education, we are closer than we have ever been to eradicating it permanently. By learning the causes, symptoms, and past of polio, and by contributing to persistent vaccination programs, each of us is helping ensure that future generations only read about polio in their history books.