Poliomyelitis

Introduction

Poliomyelitis, often referred to as Polio, is an infectious disease caused by the poliovirus. The disease is highly contagious and primarily affects children under the age of five. In severe cases, it can lead to irreversible paralysis and even death.

Etiology

The causative agent of poliomyelitis is the poliovirus, a member of the genus Enterovirus and the family Picornaviridae. The virus is small, with an icosahedral symmetry and a positive-sense single-stranded RNA genome. There are three serotypes of the poliovirus, P1, P2, and P3, each of which can cause a distinct form of the disease.

A close-up image of the poliovirus, showing its icosahedral symmetry.

Transmission

Poliovirus is transmitted primarily through the fecal-oral route, although it can also be spread through the oral-oral route. The virus is highly contagious and can spread rapidly in areas with poor sanitation and hygiene. Once ingested, the virus multiplies in the intestines and can then spread to the nervous system, causing paralysis.

Clinical Manifestations

The majority of individuals infected with the poliovirus are asymptomatic. However, in a small percentage of cases, the virus can invade the central nervous system and cause paralysis. The severity and location of the paralysis can vary, but it often affects the legs. In severe cases, the virus can paralyze the muscles involved in breathing, leading to respiratory failure and death.

Diagnosis

The diagnosis of poliomyelitis is primarily based on clinical symptoms, particularly the presence of acute flaccid paralysis. Laboratory confirmation can be obtained through isolation of the virus from a stool sample or a throat swab. Serological testing can also be used to detect antibodies to the virus.

Treatment

There is no specific treatment for poliomyelitis. Management of the disease primarily involves supportive care, including pain relief, physiotherapy to prevent deformity and maximize mobility, and respiratory support in severe cases.

Prevention

The primary method of prevention is vaccination. Two types of vaccine are available: the oral polio vaccine (OPV) and the inactivated polio vaccine (IPV). Both vaccines are highly effective at preventing the disease.

Eradication Efforts

The World Health Organization (WHO) launched the Global Polio Eradication Initiative in 1988, with the aim of eradicating the disease worldwide. As of 2021, polio remains endemic in only two countries: Afghanistan and Pakistan.