CDC – Polio
Polio, sometimes called poliomyelitis, is caused by the poliovirus. This virus can be mild and cause mild or, even, no symptoms. It can also be severe and cause paralysis and, sometimes, death. Some individuals with the virus may have sore throat, fever, tiredness, nausea, headaches, and stomach pain with symptoms only lasting 2-5 days. However, others will go on to develop meningitis (infection of the covering of the spinal cord and/or brain) or paralysis. It is impossible to tell who, if infected, will develop which set of symptoms.
The poliovirus is extremely contagious and is spread through person-to-person contact as it only infects people. The virus lives in the infected individual’s throat and intestines, so it can be spread through respiratory droplets or their contaminated feces (poop). An infected person can spread the virus immediately before the symptoms develop and up to two weeks after symptoms appear.
Even if someone fully recovers from polio, they can develop a condition called post-polio syndrome (PPS) that causes muscle weakness, tiredness, and joint pain. PPS usually begins developing anywhere from 15-40 years after the initial infection. As with the initial infection, it is impossible to tell who will go on to develop PPS. PPS is not contagious.
The poliovirus vaccine is incredibly effective and helped eradicate the disease in the United States. However, the vaccine is still necessary, as this virus is still present in other countries and can be acquired while traveling.