Poliomyelitis is an infectious viral disease affecting the nervous system of infants. It is caused by the polio virus and transmitted by fecal contamination. Polio can be of two types – the paralytic and the non-paralytic.
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Infection with the poliovirus causes poliomyelitis. These are RNA viruses belonging to the Enterovirus family inhabit in the gastrointestinal tract, particularly the intestine and the oropharynx. Once infected with the polio virus, it takes anywhere from 6 to 20 days for the symptoms to appear. Three serotypes of the virus have been identified – PV1, PV2, PV3 of which PV1 is the most common and virulent strain that is closely linked with paralysis.
Polio is a contagious disease that is transmitted by ingestion of fecal contaminated water or food. During the initial phase of the infection, the individual excretes fecal matter loaded with the infectious viral particles. Risk factors that increase the probability of infection are malnutrition and immune deficiency.
Paralytic polio affects about 1% of those infected with the virus. Once the virus enters the body it spreads via the nerve fiber pathways and in the process replicate and destroy motor neurons within the brain stem, cortex and spinal cord, causing paralytic poliomyelitis. The severity of the damage depends on the amount of damage suffered by the neurons and the part of the Central Nervous System affected.
Laboratory diagnosis of polio involves examination of the stool samples and/or throat swabs of an individual suspected with the infection. Antibody assays are performed on the blood samples of the suspect. Once the patient is tested positive by these initial diagnostic tests, further confirmation is done by genetic mapping or PCR technology. These advanced techniques not only confirm the infection, but also help determine the source of infection – wild type due to natural reasons or vaccine type due to the polio vaccine.
Prevention is better than cure, but in the event of an infection, the disease can only be managed. It cannot be cured and leaves long-lasting effects on the survivor. Course of treatment for a person infected with polio virus includes administration of medication for alleviation of the symptoms, speedy recovery and prevention of complications. Medications include antibiotics to prevent secondary infections, muscle relaxants and analgesics for pain relief, nutritious diet and physiotherapy.
For those afflicted with paralysis of the limbs, long-term rehabilitation is necessary in the form of orthopedic surgery, prosthetics, corrective shoes and braces.
Polio is an infectious disease but can be prevented by vaccination. Two types of vaccination are administered – Live attenuated vaccine also known as the Oral Polio Vaccine (OPV) and the Inactivated Polio Vaccine (IPV). Both the vaccines are equally effective, but OPV is inexpensive and carries a minute chance of infection while IPV is expensive and is completely non-infectious.
Polio had assumed epidemic proportions in the early 1900s and became the subject of global health policies in the mid 1950s. Due to rapid immunization programs of WHO and UNICEF, several countries have been eradicated of this dreaded disease and are now polio-free. The ultimate aim is to eradicate polio from the face of the earth.