Definition:
It is a viral infection often characterized by the acute onset of flaccid paralysis (poliovirus infection occurs in the gastrointestinal tract and spreads to adjacent lymph nodes, and in a minority of cases, the infection travels to the central nervous system). Polio is also defined as a highly contagious viral disease; the virus enters the human body through the mouth, multiplies in the intestines, and invades the nervous system, capable of causing total paralysis within a matter of hours. It mostly affects children under five years of age.
Causes of the Disease:
The poliovirus belongs to the enterovirus genus, consisting of types 1, 2, and 3, and all types can cause paralysis.
Vulnerable Groups:
This disease primarily affects children under the age of five.
Modes of Transmission:
- Person-to-person transmission occurs through the contamination of food or drink with the poliovirus.
- The virus is also transmitted via respiratory droplets and saliva contaminated with the poliovirus.
Incubation Period:
The incubation period ranges between 3 and 35 days, and between 7 and 14 days for paralytic cases.
Symptoms and Signs
Abortive Poliovirus Infection:
This occurs in about 4%–8% of infections and is characterized by a mild illness unaccompanied by paralysis, presenting with fever for two or three days, malaise, muscle pain, and possibly a headache. These symptoms cannot be distinguished from those caused by many other viruses.
1. Non-Paralytic Polio:
Polio causes mild, flu-like signs and symptoms such as:
- Fever.
- Sore throat.
- Headache.
- Vomiting.
- Fatigue.
- Back pain or stiffness.
- Neck pain or stiffness.
- Pain or stiffness in the arms or legs.
- Muscle weakness.
- Meningitis.
2. Paralytic Polio:
This occurs in less than 0.1% of all poliovirus infections. Symptoms occur in two stages: the first is similar to non-paralytic polio, after which the symptoms progress to the second stage, which includes:
- Muscle pain.
- Flaccid paralysis.
- Stiffness in the neck and back.
Diagnosis
In many instances, doctors recognize polio through symptoms, but the infection is confirmed by:
Laboratory Testing:
The virus is isolated by culturing a stool sample taken from the suspected case or a contact (the currently approved test according to the World Health Organization recommendation).
Treatment
There is no cure for polio; the focus of modern treatments is on relieving symptoms.
Prevention
The disease currently has no cure, and the only method to prevent it is to immunize children with the scheduled doses of the polio vaccine. In the Kingdom, the inactivated polio vaccine (IPV) as well as the oral polio vaccine (OPV) are used—administered as two drops in the child's mouth. These doses are given according to the following schedule:
A) Primary Doses:
- First Dose of the Inactivated Polio Vaccine (IPV): at the age of (2 months).
- Second Dose of the Inactivated Polio Vaccine (IPV): at the age of (4 months).
- Third Dose of both the Inactivated (IPV) and Oral (OPV) Polio Vaccines together: at the age of 6 months.
B) Booster Doses:
- First Booster Dose: at the age of 18 months using the Oral Vaccine (OPV).
- Second Booster Dose: upon school entry using the Oral Vaccine (OPV).
C) Additional Doses:
These doses are determined by health authorities based on available data regarding the spread of the disease, and are implemented in the form of campaigns during which all children are immunized.