What is the history of polio?
Polio is caused by a virus and has been around for thousands of years. There are even Egyptian artifacts portraying individuals with typical features of post-polio paralysis. Polio has been called many different names, including infantile paralysis, debility of the lower extremities, and spinal paralytic paralysis. We now refer to the virus and disease as polio, which is short for poliomyelitis and has Greek derivation: polios (gray), myelos (marrow), and itis (inflammation).
Polio is caused by a very infectious enterovirus, poliovirus (PV), which primarily affects young children and is spread through direct person-to-person contact, with infected mucus, phlegm, feces, or by contact with food and water contaminated by feces of another infected individual. The virus multiplies in the gastrointestinal tract where it can also invade the nervous system, causing permanent neurological damage in some individuals.
Most individuals infected with polio remain asymptomatic or develop only mild flu-like symptoms, including fatigue, malaise, fever, headache, sore throat, and vomiting. In fact, the symptoms, if present, may only last 48-72 hours; however, those individuals will continue to shed virus in their stools for a prolonged period, serving as a reservoir for subsequent infections. About 2%-5% of infected individuals go on to develop more serious symptoms that may include respiratory problems and paralysis. Currently, there is no cure for polio; only vaccination can prevent the spread of the disease, and although in the developed world it is almost unheard of, globally, polio remains a fairly common disease. Originally, international organizations believed it possible to eradicate polio by 2000, though this has been more difficult than initially hoped for.
What causes polio?
The symptoms of polio are caused by the poliovirus, which is a small RNA virus that is spread through contact with the oral mucosa (mouth, nose, etc). Most commonly, the virus attaches to and infects intestinal cells, multiplies, and is excreted in the stool of the infected individual. Rarely, in 2% of the cases, the virus spreads from the gastrointestinal tract to the nervous system and causes paralytic disease.
How is polio spread?
Polio is spread in an “oral-fecal” manner. Person-to-person infection occurs by contact with infected mucus, phlegm, feces, or by contact with food and water contaminated by feces of another infected individual.
What are signs and symptoms of polio?
The signs and symptoms of polio differ depending on the extent of the infection. Signs and symptoms can be divided into paralytic and non-paralytic polio.
In non-paralytic polio which accounts for most individuals infected with polio, patients remain asymptomatic or develop only mild flu-like symptoms, including fatigue, malaise, fever, headache, sore throat, and vomiting. The symptoms, if present, may only last 48-72 hours, though usually they last for one to two weeks.
Paralytic polio occurs in about 2% of people infected with the polio virus and is a much more serious disease. Symptoms occur as a result of nervous system and spinal cord infection and inflammation. Symptoms can include