Poliomyelitis, or Polio is a crippling and potentially deadly infectious disease. It is caused by the poliovirus. The virus spreads from person to person and can invade an infected person’s brain and spinal cord, causing paralysis (can’t move parts of the body). Most people who get infected with poliovirus (about 72 out of 100) will not have any visible symptoms.
About 1 out of 4 people with poliovirus infection will have flu-like symptoms that may include:
These symptoms usually last 2 to 5 days then go away on their own.
A smaller proportion of people with poliovirus infection will develop other more serious symptoms that affect the brain and spinal cord:
Paralysis is the most severe symptom associated with polio because it can lead to permanent disability and death. Between 2 and 10 out of 100 people who have paralysis from poliovirus infection die because the virus affects the muscles that help them breathe.
Even children who seem to fully recover can develop new muscle pain, weakness, or paralysis as adults, 15 to 40 years later. This is called post-polio syndrome. Note that "poliomyelitis" (or "polio" for short) is defined as the paralytic disease. So only people with the paralytic infection are considered to have the disease.
Poliovirus only infects humans. It is very contagious and spreads through person-to-person contact. The virus lives in an infected person’s throat and intestines. It enters the body through the mouth and spreads through contact with the feces (poop) of an infected person and, though less common, through droplets from a sneeze or cough. You can get infected with poliovirus if you have feces on your hands and you touch your mouth. Also, you can get infected if you put in your mouth objects like toys that are contaminated with feces.
An infected person may spread the virus to others immediately before and about 1 to 2 weeks after symptoms appear. The virus can live in an infected person’s feces for many weeks. It can contaminate food and water in unsanitary conditions.
People who don’t have symptoms can still pass the virus to others and make them sick.
Due to the frequency and speed of worldwide travel, continued immunization and vigilance are required to maintain any area’s freedom from polio. Clinicians are the most likely to first suspect a case of breakthrough polio. Even a single suspected paralytic polio case should be reported immediately to state and local health departments and then to the CDC at 404-639-8255. Be prepared to give preliminary clinical and other information, such as the patient’s vaccine history and any patient contact with the oral polio vaccine. Two cases of suspected paralytic polio suggest the presence of virus in 200 asymptomatic or mildly symptomatic persons. Also, this would suggest a potential for wild polio transmission and should be reported as above, with urgency. Two cases of suspected paralytic polio would require outbreak control, with vaccination of everyone in the epidemic area whose vaccine histories are uncertain, from the age of 6 weeks and older. Persons who have a history of polio disease also should be immunized with IPV, as the likelihood that they have had all three serotypes of polio is low; they may be susceptible to the other two serotypes and need vaccine protection.
The need to obtain specimens early in the disease course is vital. Two stool specimens, 24 hours apart, during the first 14 days after the onset of paralytic disease give the highest likelihood of poliovirus isolation; two pharyngeal swabs, 24 hours apart, give an intermediate likelihood of poliovirus isolation. Any suspected polio case in a member of a group (religious or otherwise) abstaining from vaccination must be assigned the highest priority for urgent follow-up and specimen collection.
Due to United States’ success in eliminating polio, the more powerful oral polio vaccine is no longer used in this country, although this vaccine is still appropriately in use globally. In countries where polio is currently endemic or during polio outbreaks, the oral polio vaccine remains the best strategy for reducing the total number of cases of polio infection.