Polio: A Crippling Disease
Medikoe Health Expert
Koramangala, bengaluru, karnataka, india, Bengaluru Feb 10, 2017
Polio, or poliomyelitis, or infantile paralysis, is a debilitating and potentially lethal infectious disease. This is caused by a virus called Poliovirus (PV) which causes muscle weakness resulting in an inability to move. This can occur over a few hours to a few days. The weakness most often involves the legs, but may less commonly involve the muscles of the head, neck, and diaphragm.
Symptoms of Polio
There are two basic patterns of polio infection
- A minor illness, which does not involve the central nervous system (CNS), sometimes called abortive poliomyelitis, and
- A major illness, involving the CNS, which may be paralytic or nonparalytic.
Mostly PV symptoms are asymptomatic.
Rarely, the infection produces minor symptoms; these may include:
- Upper Respiratory tract infection (Sore throat and fever),
- Gastrointestinal disturbances (nausea, vomiting, abdominal pain, constipation or, rarely, diarrhea), and
- Influenza-like illness.
The virus enters the central nervous system in about 1 percent of infections. Most patients with CNS involvement develop nonparalytic aseptic meningitis, with symptoms:
- Headache, neck, back, abdominal and extremity pain
- Lethargy, and
About five in 1000 cases progress to paralytic disease, in which the muscles become infirm, floppy and uncontrolled, and, finally, conclusively paralyzed; this condition is known as acute flaccid paralysis.
Paralytic polio may also be classified as:
Spinal polio: The virus affects the motor neurons in the spinal cord that causes paralysis in the arms and legs, and also causes breathing problems.
Bulbar polio: The virus affects the neurons responsible for senses say sight, taste, and breathing.
Bulbospinal polio: The virus affects both spinal and bulbar polio.
The post-polio syndrome describes symptoms that develop in patients about 30 to 40 years after exposure to acute polio illness. The cause of acute polio illness is unknown.
Symptoms of the post-polio syndrome include
Pain in muscles
Spinal changes such as scoliosis, spondylosis, and/or secondary nerve root and peripheral nerve compression.
Slowly intensifying muscle weakness(any muscles, including the eye muscles and sometimes, termed bulbar polio), generalized fatigue, and intolerance to cold may also occur.
Causes of Polio
The poliovirus is spread through the feces of an infected person. This is quite evident in areas with poor sanitation where the virus is contagious enough to get spread from feces to water supply, or, by touch, to food. Individuals suffering from polio can spread it via feces for weeks, even if their symptoms are not prominent. Direct contact with a person infected by poliovirus can also lead to infection. Once it enters the body it infects the cells of the throat and intestine. The virus stays within the intestines, before spreading to other areas of the body. Eventually, the virus moves into the bloodstream where it can spread to the entire body and can further exacerbate the illness.
Diagnosis of Polio
Laboratory diagnosis of PV can be done by recovering poliovirus from the fecal sample or a swab of the pharynx. Antibodies produced against PV can be diagnostic and are generally detected in the blood of the infected patient in the early stages.
Paralytic polio can be diagnosed by analyzing cerebrospinal fluid of the patient which is done by lumbar puncture shows a significantly increased number of white blood cells. Most of the symptoms are visible and easily diagnosable such as neck and back stiffness, abnormal reflexes, and trouble with swallowing and breathing.
Treatment of Polio
There is no cure for polio. The focus of modern treatment has been on providing relief of symptoms, speeding recovery and preventing complications.
Polio can be prevented by the use of the following two vaccines:
Inactivated poliomyelitis vaccine (IPV)
Oral polio vaccine (OPV)
Oral polio vaccine (OPV); sabin vaccine: It is the live virus available in 10 ml and 50 ml vials; each dose is 2 drops, dropped directly in the mouth. The virus multiplies in the intestines and produces active immunity, simulating natural infection, without producing symptoms of the disease. This is the vaccine of choice in many countries because it is economical, easy to administer, and gives an excellent level of immunity. It is also vaccine of choice for active immunization of children because it is simple to administer, is well accepted, induces systemic as well as intestinal immunity (the portal of entry of disease virus) and is highly efficacious.
Inactivated poliomyelitis vaccine(IPV); Salk vaccine: It is inactivated suspension of the virus and is preferred over OPV for-
Primary immunization in adults (risk of vaccine-induced paralysis following OPV is higher in adults)
For people with a compromised immune system.
Fever and local pain are common. Allergic reactions sometimes occur, probably to the animal protein present in the vaccine.
Concurrent vaccination of all infants and children up to 5 years of age has eradicated the wild virus in many countries through the pulse polio program.
Polio is caused by RNA viruses. They are members of the enterovirus group. There are three types (types 1, 2, and 3) of polioviruses; type I is responsible for about 85% of all paralytic infections. These types are antigenically distinct strains from each other and infection or immunity to one type does not protect against the other two types, however, once immunity is established to one or all of the three strains, immunity is lifelong. They are found to be deadly on their own and can cause permanent damage to spinal cord cells.
In 2014 in California, an outbreak of illness was marked for its resemblance to polio which retrospectively dated back to 2012. All of the affected children developed rapid onset of paralysis in one or more limbs and when analyzed showed a consistent injury to the central spinal cord. All the children were vaccinated against polio and some were positive to enterovirus, a virus known to be associated with limb paralysis and breathing difficulties. The researchers are trying to determine the cause and treatment of the illness as they are quite convinced that it’s not polio. It is now called acute flaccid myelitis.
To date, children suffering from acute flaccid myelitis have not responded to steroid or immunoglobulin treatment. This new outbreak of polio-like illness is being intensely investigated by agents from the U.S. Centers for Disease Control and Prevention.
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