|Photo of the polio virus by Dr. Fred Murphy|
and Sylvia Whitfield at the CDC,
public domain image
Polio is caused by a virus. The disease usually - but not always - affects children under the age of five. Many people never develop symptoms from the infection and don't know that they've been infected by the virus. Some people develop non-paralytic polio, whose symptoms resemble those of the flu. Sadly, according to WHO (the World Health Organization), one in 200 infections produces irreversible paralysis, which can be deadly if the respiratory muscles are paralyzed. 5% to 10% of those paralyzed lose the ability to breathe.
The polio virus is very contagious. It enters the mouth from food or water contaminated with virus-laden feces and travels through the digestive tract. The virus multiples in the intestine and enters the nervous system. The virus also replicates in the respiratory tract and may be transmitted from one person to another via sneezes and coughs.
Paralytic polio begins with flu-like symptoms, just like non-paralytic polio. The symptoms include fever, headache, vomiting and fatigue. A stiff or painful neck, back pain and arm or leg pain are generally present as well. In the paralytic form of the disease, paralysis may appear in less than a week.
Unfortunately, some people who recover from polio develop a condition called post-polio syndrome. This condition may appear years after the polio experience. It's generally not life-threatening, but it may very well be life-altering. Symptoms include muscle weakness and fatigue.
Polio can't be treated, but there is a highly effective vaccine to prevent it (the inactivated polio vaccine, or IPV). Multiple doses of the vaccine are needed to provide immunity. It's important that people protect themselves from the disease to prevent its possibly serious effects.