Polio classification

The term poliomyelitis is used to identify the disease caused by any of the three serotypes of poliovirus (P1, P2 and P3). Most cases of poliovirus infection are asymptomatic. For symptomatic cases, two basic disease patterns are described: a minor form which does not involve the central nervous system (CNS), sometimes called abortive poliomyelitis, and a major form involving the CNS, which may be paralytic or non-paralytic.^[1] According to the ELCPPC classification, the paralytic form of the disease may be classified into: sporadic, epidemic; epidemiologically abnormal; or imported.^[2]

In most people with a normal immune system, poliovirus infection is asymptomatic. Patients with subclinical poliomyelitis often acquire active immunity against future infections, caused by the same viral strain.^[1]

Abortive poliomyelitis is a mild form of poliomyelitis, often presenting with symptoms of gastroenteritis, such as: fever, nausea, vomiting, diarrhea, or constipation; or symptoms of acute respiratory infection, such as: fever, headache, and sore throat.^[1]

Patients with this form of poliomyelitis often present with symptoms of non-paralytic meningitis, such as: fever; headache; vomiting; lethargy; irritability; neck, back, abdominal and upper or lower limb pain. Muscle spasm usually occurs in the neck, back and hamstring muscles.^[1]

Patients with paralytic poliomyelitis present with the same symptoms as those of the non-paralytic form. Additional symptoms in the paralytic form include: muscle weakness; asymmetrical paralysis; muscle atrophy; tremors; and skeletal deformities.^[3][1][4]

Paralytic poliomyelitis may be classified into 2 forms, that may coexist in the same patient:

This form of the disease affects the muscles supplied by spinal nerves.

This form of the disease affects the muscles supplied by cranial nerves. Encephalitis may also occur in this form.

Until 1976, paralytic poliomyelitis was classified according to the epidemiological data. The ECPPC, or Epidemiologic Classication of Paralytic Poliomyelitis Cases, distributed these cases into 1 of 4 categories:^[2]

• Epidemic
• Endemic
• Imported
• Immune deficient

In 1985, a new classification was proposed, in order to incorporate, not only epidemiological information but also viral isolation, and characterization of the viral strain. This new classification was named ELCPPC, or Epidemiologic and Laboratory Classification of Paralytic Poliomyelitis Cases, and it classifies paralytic poliomyelitis according to the following classes:^[2]

Any case of poliomyelitis that is not epidemiologically related to another, and that may be caused by either the wild form of the virus, or by the virus in the vaccine.

When a case of the disease is epidemiologically linked to a similar case. The virus may, or may not, be related to the virus in the vaccine.

Any presumed or confirmed case of poliomyelitis that may be caused by either the wild form of the virus, or by the virus in the vaccine, irrespectively to the origin of the host’s immunological deficiency.

Any new case of poliomyelitis in a person who has entered the US (either foreign or US resident), and that has been symptomatic for the previous 30 days of entrance, or that develops symptoms during the initial 30 days in the country.

Template:WH Template:WS