Poliomyelitis and the Epidemics
Poliomyelitis, a neuromuscular disease also known as infantile paralysis, is caused by the poliovirus of which there are three types. Infection occurs by fecal/oral contamination. The virus replicates in the gastrointestinal tract and is carried by the blood throughout the body. In 1%-2% of the infections, the poliovirus invades the nerve cells (motor neurons) of the spinal cord. When it does, muscles connected to the damaged or destroyed nerve cells can no longer properly function, resulting in weakness or paralysis of the limbs, and, possibly, the muscles controlling speech, swallowing, and breathing.
Poliomyelitis dates back to at least 1350 BC. Major epidemics occurred in Stockholm, Sweden (1887, 1905, 1911) and in Vermont, United States (1894). In 1916, the great New York epidemic killed 6,000 people and left 27,000 disabled. The number of cases reported during the '40s ranged from a low of 4,167 in 1942 to a high of 42,033 in 1949. The largest number of cases ever reported in the United States was over 58,000 in 1952.
The vaccine developed by Jonas E. Salk, using killed or inactivated poliovirus (IPV), was made available by injection in 1955. The oral polio vaccine (OPV), developed by Albert B. Sabin using the live but weakened poliovirus, was approved for use in 1962.
Acute Poliomyelitis in the World Today
As of August 2002, there were 483 confirmed cases of acute poliomyelitis reported to authorities worldwide. It should be noted that not every case is reported. The World Health Organization (WHO) target date for worldwide certification is 2005. Certification is the process that verifies that a region is polio-free. To date, the Region of the Americas (36 countries), the Western Pacific Region (37 countries and areas including China), and the WHO European Region (51 countries) have been certified polio-free. Acute poliomyelitis is now found only in parts of Africa and South Asia. A main resurgence of polio occurred in Northern India in late 2002 with 1,554 cases detected nationwide.
The last case of acute poliomyelitis in the Western Hemisphere caused by the wild poliovirus (that naturally occurs in the environment) was reported in Peru in 1991. During the last half of 2000, seven laboratory-confirmed cases of poliomyelitis were reported in the Dominican Republic and Haiti. The isolated virus is unusual because it was derived from the oral poliovirus vaccine (OPV). Mass vaccination campaigns have been conducted in both of these nations.
All of the new cases of poliomyelitis reported since 1979 in the United States have been caused by the oral polio vaccine (OPV), the “live” vaccine. The number of vaccine-associated cases confirmed in 1995, 1996, 1997, and 1998 was 6, 5, 3, and 1, respectively. As a result of these cases, The National Childhood Vaccine Injury Act of 1986 (PL-99-660) created a no-fault compensation alternative to suing manufacturers. The Centers for Disease Control and Prevention and the Federal Drug Administration developed a Vaccine Adverse Event Reporting System (VAERS) to collect data on the reactions to all vaccines.
In an effort to decrease the number of vaccine-associated cases of polio caused by an all-OPV schedule, the United States Advisory Committee on Immunization Practices (ACIP) changed its policy on polio vaccination in early 1997, and again, in June 1999. The recommended IPV-only immunization schedule took effect January 1, 2000. No cases of acute poliomyelitis have been reported in the United States since 1999.
The WHO recommends an all-OPV schedule in the mass campaign to eradicate the poliovirus from the world.
Denmark uses a sequence of IPV and/or OPV. France, The Netherlands, and Canada use IPV exclusively. Australia, Germany, New Zealand, Switzerland, and the United Kingdom use the OPV (except for special cases).
The Late Effects of Poliomyelitis
The World Health Organization estimates there are up to 20,000,000 survivors of poliomyelitis living in the world today.
Preliminary numbers from a National Health Interview Survey (1996) estimate that there are 1,000,000 survivors of polio in the United States.
Of the 1,000,000 survivors of polio in the United States, 450,000 are living with the effects of permanent paralysis, ranging from unequal leg lengths resulting in a limp to paralysis of the breathing muscles resulting in the use of a ventilator.
The occurrence of new muscle weakness and atrophy, many years after acute poliomyelitis, was first reported in the medical literature in 1875.
In the late '70s, polio survivors started to report that they were “tiring more easily” and that they were in search of physicians who were knowledgeable about poliomyelitis. The sheer weight of numbers of polio survivors from the epidemics of the '40s and '50s compelled medical professionals to begin to address the problem.
The triad of major symptoms includes inordinate fatigue, new muscle weakness with or without loss of muscle bulk, and muscle pain with possible muscle twitching. Other symptoms include sleeping problems, breathing difficulties, decreased ability to tolerate cold temperatures, joint pain, and a noticeable decline in the ability to carry out customary activities.
Research suggests that 120,000-180,000 polio survivors may be developing “post-polio syndrome.” The diagnosis is based on the following general criteria: prior episode of paralytic polio; period of functional stability; gradual or abrupt new weakness usually accompanied by the health problems listed above; exclusion of other medical, orthopedic, and neurologic conditions that may cause the same symptoms.
Nerve cells damaged by the poliovirus during the acute stage of poliomyelitis left the accompanying muscles orphaned and paralyzed. During recovery, the surviving nerve cells “sprouted” and reconnected to the orphaned muscles. The nerve and muscle combination is called a motor unit, and the most widely accepted explanation of the new weakness is a dysfunction of the motor unit.
For diagnosed post-polio syndrome, the current treatment, which must be unique to each individual, is the management of the symptoms. The specific cause(s) of the symptoms need(s) to be identified and treated and/or eliminated. Many times the cause is overuse; however, disuse also can result in new weakness.
Although some physicians use exacting criteria for the diagnosis of “post-polio syndrome,” many physicians and polio survivors alike acknowledge that aging polio survivors will encounter “wear and tear” musculoskeletal problems. Thus, whatever the cause and whatever the label of the diagnosis, there are consequences to living long-term with the late effects of poliomyelitis.
Surveys of polio survivors cite the following lifestyle changes as the most beneficial: adopting energy conservation techniques, employing household help, buying special equipment, modifying the home, cutting back on work, and implementing a general conditioning exercise program.
Polio survivors are advised to examine their daily schedules, both at work and at home, and modify, if necessary, the intensity and timing of their activities by utilizing appropriate energy-saving techniques and equipment.
The role of exercise is controversial. Recent research indicates that supervised, low intensity, interval exercise can increase strength with no apparent damage. Polio survivors are best advised to heed their bodies' warning signs of pain. The general recommendation is to avoid activity that causes pain and fatigue after ten minutes.
Limited research has been conducted on medications to address muscle fatigue. No medicine has been found in controlled studies to provide consistent and significant benefits.
In 1987, the Social Security Administration acknowledged the late effects of poliomyelitis and issued criteria for the evaluation of the ability of polio survivors to continue employment in its Program Operations Manual System (POMS). The listing number is DI 24580.010E.3.
Polio survivors are also susceptible to all the other diseases that affect the general population. One study revealed that 35% of the individuals complaining of post-polio problems had another medical condition such as diabetes; other secondary conditions included obesity and elevated cholesterol.
In treating other conditions, polio survivors should be aware that the side effects of some medications are weakness and fatigue; taking those medications can noticeably increase post-polio symptoms. Also, the recovery time after injury, surgery, and other illnesses is reported by polio survivors to be longer. Polio survivors facing surgery should seek a consultation with the anesthesiologist (READ MORE) to discuss prior medical history related to poliomyelitis.
Many survivors express concern over the lack of knowledge and adequate assistance from medical professionals about issues related to poliomyelitis. Through the networking efforts of many, more professionals are gaining expertise and do provide sound advice. However, polio survivors must educate themselves, be resourceful, and work in collaboration with open-minded health professionals.
To assist with the education of polio survivors and health professionals, International Polio Network has available the Handbook on the Late Effects of Poliomyelitis for Physicians and Survivors (Revised edition, 1999). International Polio Network also publishes the quarterly Polio Network News and compiles an annual Post-Polio Directory of clinics, health professionals, and support groups.