Polio is composed of a RNA genome and a protein capsid.

Polio infects human cells by binding to an immunoglobulin like receptor, CD155 on the cell surface.

Polio is a highly infectious disease. There are 3 different types of polio Virus: PV1, PV2 and PV3. These types of polio are distinguished by their capsid proteins. This will determine their interaction with host cells.

Polio is only transmitted from human to human and is not transmitted from animal to human.

This can lead to issues with motor neurons that control muscle movement, respiratory muscles that control breathing and brain stem that can cause meningitis, encephalitis or other neurological problems.

Meningitis is inflammation of the protective membranes surrounding the brain and spinal cord. Encephalitis is inflammation of the brain.

Polio can survive in high acidic conditions, such as the stomach, making it easier to spread throughout the body. This fact plays a role in being apart of the Picornaviridae family.

Someone can also obtain the virus by eating raw or under cooked meat or drink water that is contaminated with the feces of someone that is already infected. Someone can get the virus by touching a contaminated object, unknowingly, and putting their hands on their mouth.

There are 2 different types of vaccinations for polio: inactivated polio vaccine and oral polio vaccine. IPV contains a killed (inactivated) virus whereas OPV contains a live, weakened virus. In the United States, only IPV is used. IPV is the only vaccine that has been used for polio in the USA since 2000.

There are 4 total doses of vaccine for polio. Polio vaccinations is recommended at the age of 2 months, 4 months, 6-18 months and between the age of 4-6 or prior to starting school.

It is recommended to treat the symptoms of polio due to there being no cure. Many physicians would try to manage the current symptoms and prevent any further complications.

Physicians would recommend treating the mild symptoms such as; Tylenol or Ibuprofen for pain or fever, warm compression for muscle/joint pain and bed rest due to fatigue.

Patients that had severe symptoms may require additional treatment. Many patients that experienced muscle weakness, partial paralysis would require physical/occupations therapy for maintain currently muscle strength/flexibility, maintain mobility and prevent deformities.

Patients that had permanent weakness or issues with ambulation would require leg bracing and/or the use of a walker to assist with ambulation.

Patients that experienced weakness/paralysis of the diaphragm would require treatment of a ventilator to assist with breathing due to muscle weakness.

Abortive polio is considered a mild version of polio. Approximately 5% of infected people will have mild symptoms. Typically these symptoms mirror flu like symptoms such as: fever, fatigue, headache, nausea/vomiting or diarrhea. Abortive polio usually is short lived and will last between 24-72 hours and will make a full recovery.

Non paralytic polio is considered a milder form of polio. Approximately 1% of infected people will have increased symptoms. Symptoms are the same as listed above, however, accompanied with neck pain, stiffness and an intense headache. People may have original symptoms for a few days and appear to be getting better then the second phase will start. The second phase would be the neck pain, muscle weakness/stiffness and intense headache. Patients do not experience any form of paralysis.

Paralytic polio is considered to be a very rare form of polio. The symptoms begin similar to non paralytic polio but have an increase in intense pain, tingling/pens and needles to their hands/arms, muscle spasms, weakness and eventually lead to paralysis of different parts of the body. People will have lasting effects from paralytic polio.

Physicians can swab the inside of someones mouth to obtain saliva that will be sent to a lab for processing. The lab will keep the virus isolated and identified. Swabbing is a key part of surveillance.

Stool cultures are a crucial part in diagnosing polio. Typically, 2 stool cultures are obtained, 24 hours apart and within 14 days of paralysis onset are collected to increase the chances of detecting the virus. These samples will be sent to World Health Origination lab for processing.

Blood specimen is obtained to check for antibodies of polio. This will help determine if your body has fought off the virus or if you have immunity from the vaccination.

Lumbar puncture is collected to obtain cerebrospinal fluid from the spinal canal. This procedure requires a needle to be placed into the low back to obtain the fluid. In some cases, polio can be hard to detect with results from a lumbar puncture.

The most recent countries with reports in 2025 include Afghanistan and Pakistan. These countries reported cases of wild polio, type 1, which is where it is naturally occurring polio that circulate in the environment. Type 2 polio was declared eradicated in September 2015 with the last case being reported in India in 1999. Type 3 polio was declared eradicated in October 2019 with the last case being reported in Nigeria in 2012.

There have been reports of polio virus detected in wastewater systems in several countries, including European nations.

There is no certain known explanation for post polio syndrome. It is believed it can have relations to the affect on motor neurons in the spinal cord. Polio will destroy these motor neurons, and the remaining neurons will sprout new fibers in order to grow larger. This will promote recovery to muscles but puts extra stress on the nerve cell body. It is believed that over time the stress can be too much on the nerve cell body leading to breakdown.

Symptoms of post polio syndrome include increased muscle/joint weakness that worsens, easily fatigued, loss of muscle tissue, breathing problems, sleep apnea, or decrease in tolerance of cold temperatures.

Risk factors for post polio syndrome include severity of initial polio illness, it appears the more severe the initial illness will increase the risk for post polio syndrome. The age of initial illness, it appears if initial illness occurred in adulthood then that will increase the risk of the syndrome. The recovery process appears to have an affect as well, meaning the greater the recovery of initial illness appears to increase the risk of the syndrome. This is believed due to the greater recovery initially places more stress on the nerve cell body.

Complications of post polio syndrome include increased in frequent falls due to lower extremity muscle weakness, increased fatigue that can be disabling, chronic pain, osteoporosis, chronic respiratory failure and malnutrition due to chewing difficulties due to muscles weakness.

There is no cure for post polio syndrome. Many physicians treat the symptoms of the syndrome such a as, therapy, oxygen, medications for pain and ambulation assistive devices.

In about 1 in 200 cases, irreversible paralysis will occur mainly in the arms and legs.

Mainly affects children under the age of 5.

In July 2022, there was a report of paralytic polio in an un-vaccinated adult in the US in New York. This was the first reported case in almost a decade.

There were around 16,000 cases of paralytic polio reported in the US each year in the 20th century compared to none in 2023.

The first polio vaccine arrived at Mayo clinic on April 13, 1955, one day after it was licensed in US.

Dr. Jonas Salk and colleagues developed the first polio vaccine in 1955.

Dr. Albert Sabin developed a second polio vaccine in 1961.

The polio outbreak began in 1900 in the US, with the first major epidemic in 1916 resulting in over 6,000 deaths.

In 1952, the US reached a peak outbreak reporting nearly 58,000 cases, resulting in over 3,000 deaths.

It is believed that polio killed over half a million individuals each year world-wide.

It is believed that the first recorded case of polio was in 1773 by Sir Walter Scott. It was said that Walter developed a high fever and lost the use of his right leg.

It is believed there is a chance that polio was present during ancient Egypt. There were paintings and carvings present showing people with weakened limbs and children with canes at a young age. There is a theory that Roman Emperor Claudius was stricken with polio that later caused him to walk with a limp for the rest of his life.