Polio or Poliomyelitis: Viral Paralytic Disease

Paralytic polio can lead to temporary or permanent muscle paralysis, disability and deformities of the hips, ankles and feet. Since polio immunization has become widespread, cases of polio are very rare. An ancient disease, it was first recognized as a medical entity by Jakob Heine in 1840.

Incidence of the condition

Half a centurz ago, ago in 1952, there were nearly 58,000 known cases of polio in the United States, but currently in the US, about 8 cases of polio are reported yearly. Over a third of these individuals developed paralytic polio. Of the 1/3 infected with paralytic polio, 3,000 died. These cases were usually in children, and the cause has been traced to the oral poliovirus vaccine in most cases. Infants and young children are at greatest risk and infections are more common during the summer and autumn seasons.

Signs and symptoms of poliomyelitis

There are three basic patterns of polio infection:

• Subclinical infections,
• Nonparalytic,
• Paralytic

Every stadium has its own recognizable symptoms.
 

Sub-clinical infection

• No symptoms, or symptoms lasting 72 hours or less
• Slight fever
• Headache
• General discomfort or uneasiness (malaise)
• Sore throat
• Red throat
• Vomiting

Non-paralytic poliomyelitis

Symptoms last 1 to 2 weeks

• Irritability
• Pain or stiffness of the back, arms, legs, abdomen
• Muscle tenderness and spasms in any area of the body
• Neck pain and stiffness
• Pain in the front part of neck
• Backache
• Leg pain (calf muscles)
• Skin rash or lesion with pain
• Muscle stiffness
• Moderate fever
• Headache
• Vomiting
• Diarrhea
• Excessive tiredness, fatigue

Paralytic poliomyelitis

• Fever, occurring 5 to 7 days before other symptoms
• Headache
• Stiff neck and back
• Bloated feeling of abdomen
• Swallowing difficulty
• Muscle pain
• Muscle contractions or muscle spasms, particularly in the calf, neck, or back
• Drooling
• Breathing difficulty
• Muscle weakness, asymmetrical (only on one side, or worse on one side)
• Rapid onset
• Progresses to paralysis
• Location depends on where the spinal cord is affected
• Abnormal sensations (but not loss of sensation) of an area
• Sensitivity to touch, mild touch may be painful
• Difficulty beginning to urinate
• Constipation
• Irritability or poor temper control
• Positive Babinski's reflex

Post-polio syndrome

Affecting people who have recovered from polio, post-polio syndrome is a cluster of disabling signs and symptoms that appear decades — between 10 and 40 years — after the initial illness.

Common signs and symptoms include:

• New muscle weakness in limbs
• Breathing or swallowing problems
• Sleep-related breathing disorders, such as sleep apnea
• Decreased tolerance of cold temperatures
• General fatigue and exhaustion with minimal activity
• Muscle and joint pain

Virus target tissues

Polio has also been divided into several types, depending on which part of the body is affected.

Spinal polio
This type of the disease, the most common form, attacks nerve cells in the spinal cord and may cause paralysis of the muscles in arms, legs, and respiratory muscles. Children under the age of 5 are most likely to become paralyzed in a single leg, whereas paralysis of both arms and legs is more common in adults. An affected limb becomes floppy and poorly controlled — the condition of acute flaccid paralysis (AFP).

Bulbar polio
During this type of infection the virus affects the motor neurons in the brain, where the centers of certain nerves, called the cranial nerves, are located. These nerves are involved in the patient’s ability to see, hear, smell, taste and swallow.  

Bulbospinal polio
This is a combination of both bulbar and spinal paralytic polio. It usually leads to paralysis of arms and legs and may also affect breathing, swallowing and heart function.

The cause of poliomyelitis, ways of transmission

The cause of poliomyelitis is a virus called Poliovirus, which resides exclusively in humans. It is transmitted primarily through the fecal-oral path of infection, especially in areas where ventilation and sanitation systems are inadequate. Several studies have proven that it also can be transmitted through contaminated water and food. Although people carrying the virus are most contagious seven to 10 days before and after the signs and symptoms appear, they can spread the virus for weeks thereafter through their feces.

Pathogenesis of poliomyelitis

Once the poliovirus invades a patient’s body, it multiplies in throat lining and intestinal tract, and then travels to the central nervous system through blood and lymph. While the virus moves along nerve fibers, it damages the motor neurons that normally carry messages between the patient’s brain and muscles.
The mechanism by which the virus does harm after reaching the nervous system has been well studied: In order to compensate for the missing neurons, the remaining nerve cells spread new fibers. This places added stress on the nerve cell body, which has to nourish the additional fibers. Over time, this stress may be more than the neuron can handle.

Risk factors of developing poliomyelitis

Most common risk factors of developing this serious infection are:

• Travelling to an area where polio is endemic.
• Living with or caring for someone who may be shedding wild poliovirus.
• Handling laboratory specimens that contain the virus.
• A compromised immune system, such as those occuring with the HIV infection, can make one more prone to all kinds of infections, including poliomyelitis.
• Mouth, nose, or throat trauma, such as dental surgery or a tonsillectomy.
• Extreme stress or strenuous physical activity after being exposed to the virus.

Diagnosis of poliomyelitis

There are several very effective diagnostic tools for an accurate diagnosis of poliomyelitis. Some of the most common are:

Complete medical history and physical examination

This should be the first step of poliomyelitis diagnosis

Cultures of the throat, urine, and stool

These specimens are grown on a special medium and checked for the presence of the poliovirus.

Lumbar puncture

This diagnostic tool has become routine. A special needle is placed onto the lower back and thrust into the spinal canal. A small amount of cerebral spinal fluid is removed and sent for testing to determine whether there is an infection or other problems.

Possible complications of poliomyelitis

Besides the temporary or permanent muscle paralysis, the poliovirus can cause several other complications such as:

Pulmonary edema

This potentially life-threatening condition occurs when increased pressure in lung blood vessels forces fluid into the air sacs, filling the lungs with fluid.

Aspiration pneumonia

This inflammation occurs following the inhalation of foreign material.

Urinary tract infections

These infections usually begin when bacteria enter the bladder through the urinary tract.   

Intestinal obstruction

This is a partial or complete blockage of bowels that prevents food from moving through the intestinal tract.  

Myocarditis

This infection involves the muscular layer of the heart becoming inflamed, leading to chest pain, an abnormal heartbeat, or congestive heart failure

Cor pulmonale

This condition occurs when the right side of heart can't pump hard enough to compete with the lungs' increased blood pressure.

Treatment of poliomyelitis

Unfortunately, there is no cure for the poliovirus infection. Because no cure exists, the focus is on increasing comfort and preventing complications. Supportive treatments include:

• Antibiotics for the infections
• Analgesics for the pain
• Portable ventilators for the breathing problems
• Moderate exercise
• A nutritious diet

Moist heat, heating pads, and warm towels may reduce muscle pain and spasm. Physical therapy combined with braces or corrective shoes, orthopedic surgery, or similar interventions may eventually be necessary to maximize the recovery of muscle strength and function.

Prevention and immunization

There are several prevention measures of poliomyelitis and some of those are:

1. Adequate hygiene and hand washing

2. Immunization against the poliovirus: In the US, the polio vaccine is recommended to be given at the following ages:

• 2 months
• 4 months
•  between 6 and 18 months
• between 4 and 6 years

 
Two versions of the vaccine may be administered:

IPV - Inactivated Polio Vaccine

This vaccine administered by injection at all four immunization visits. Administration of the IPV cannot cause polio, and is safe for individuals with weakened immune systems.

OPV - Oral Polio Vaccine

Administered orally, OPV has been known to cause vaccine-associated paralytic poliomyelitis (VAPP) in rare cases. It should not be given to a child if they have any of the following:

• weakened immune systems
• cancer
• AIDS or HIV infection
• allergies to neomycin, streptomycin, or polymyxin B
• are taking long-term steroids