Poliomyelitis (Infantile Paralysis): Causes, Symptoms, Transmission, Treatment and Prevention

Poliomyelitis, also known as infantile paralysis, is a highly contagious infectious disease caused by a virus belonging to the Picornaviridae family, which attacks the nervous system. The poliovirus (an RNA virus) generally affects children under 5 years of age. There are 3 types of poliovirus strains (type 1, type 2, and type 3).

The severity of the disease is determined by its high mortality rate and the resulting motor disabilities. The frequency of severe manifestations is 1 case of paralysis for every 200 subclinical infections.

Poliovirus type 1 was the primary cause of most paralytic polio cases worldwide until vaccines were administered globally. Types 2 and 3 have been considered completely eradicated since 2015.

In 1988, when the Global Polio Eradication Initiative (GPEI) was launched, the virus was present in over 125 countries and caused paralysis in approximately 1,000 children daily. Thanks to immunization efforts, the incidence of polio has decreased by up to 99% to date. In Romania, the last case of polio was recorded in 1992.

Mode of transmission

The virus spreads from person to person through contact with the feces of an infected individual, by consuming food or water contaminated with fecal matter, or through the air via droplets expectorated during sneezing or coughing.

The poliovirus is highly contagious, which is why carriers can infect non-immunized individuals, especially if basic hygiene measures are not followed. Proper hand hygiene, especially washing with soap and water for at least 20 seconds, can significantly reduce the risk of virus transmission. Additionally, disinfecting surfaces and frequently touched objects, such as door handles or work surfaces, can help eliminate the virus and prevent infection.

Transmission of the poliovirus from human to animal is not possible.

Symptoms

The poliovirus enters the oropharynx and multiplies locally in the tonsils, in the lymph nodes of the neck, and subsequently in Peyer's patches and the small intestine. The polio virus enters cells, allowing it to spread to the nervous system, affecting the spinal cord and leading to muscle atrophy and limb paralysis.

The incubation period is usually 6-20 days. Infected individuals are contagious 7-10 days before the onset of symptoms, and virus shedding occurs for 5 to 10 days via nasopharyngeal secretions and for 2 to 3 weeks (sometimes even up to 4-6 months) via feces.

Most patients infected with the polio virus will not exhibit any symptoms, and in some cases, patients may have minor, flu-like symptoms such as fever, fatigue, nausea, headache, or pain in the limbs. Self-limiting episodes of gastroenteritis or respiratory tract infections may also occur.

Severe forms of the disease are rare. The initial signs and symptoms of paralytic polio, such as fever and headache, often mimic those of non-paralytic polio. However, within a week, other signs and symptoms appear, including:

• loss of reflexes
• severe muscle pain
• temporary or permanent muscle paralysis

Diagnosis

Diagnosis is made by a neurologist. A new neurological assessment exam will be performed 60 days after the onset of paralysis to determine the degree of motor deficit recovery.

Other laboratory tests may also be necessary, including:

• stool tests (stool culture)
• pharyngeal swab to investigate other enteroviruses
• blood tests to determine antibody titers (2 samples will be collected to track antibody dynamics)
• CSF (if the investigating physician deems a lumbar puncture necessary for differential diagnosis)

Treatment

There is no cure for polio. Furthermore, there is no effective antiviral treatment.

Bed rest and high intake of fluids and sugars are recommended. Certain antipyretics or painkillers may be administered to alleviate symptoms, as well as B-group vitamins orally or intravenously. In some cases, the use of portable ventilators may be necessary to facilitate breathing.

Patients presenting with peripheral motor deficit syndrome must be admitted to a medical institution.

Prevention

Polio has been eliminated with the help of vaccination. However, the virus continues to circulate in different parts of the world, such as Afghanistan, Nigeria, and Pakistan, which remain endemic areas.

In Romania, the oral polio vaccine (OPV, live attenuated vaccine) was administered until 2008, and it was replaced in 2009 by the inactivated polio vaccine (IPV). The replacement of OPV with IPV has eliminated cases of paralysis associated with the oral polio vaccine.

Any person who did not receive a complete series of vaccines (three doses at 2, 4, and 6-18 months, one dose at 4-6 years) in childhood must complete the vaccination schedule as soon as possible.

References
http://medfam.ro/books/infectioase/poliomielita.htm
https://www.who.int/news-room/fact-sheets/detail/poliomyelitis
https://www.cedars-sinai.org/health-library/diseases-and-conditions/p/polio-poliomyelitis.html
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4212416/
https://www.cnscbt.ro/index.php/polio
https://www.cnscbt.ro/index.php/metodologii/paf/458-metodologia-de-supraveghere-a-paraliziei-acute-flasce-si-de-mediu/file
https://www.sfatulmedicului.ro/Meningita-si-alte-infectii-ale-sistemului-nervos/poliomielita-paralizia-infantila-infectia-cu-virusul-poliomielitic_663#Tratament
http://medfam.ro/books/infectioase/poliomielita.htm
https://doc.ro/sanatate/poliomielita-tipuri-factori-de-risc-simptome-tratament