Polio (also know as poliomyelitis), is a contagious viral disease that attacks the central nervous system and that can cause temporary or permanent paralysis and weakness.
Signs and Symptoms:
Polios is a viral illness that, in about 95% of cases, actually produces no symptoms at all (asymptomatic polio). In the 4% to 8% of cases in which there are symptoms (symptomatic polio), the illness appears in three forms:
- A mild form abortive polio (most people with this form of polio may not even suspect they have it because their sickness is limited to mild flu-like symptoms such as upper respiratory infection, diarrhea, fever, sore throat, and a general feeling of being ill).
- A more serious form associated with aseptic meningitis called nonparalytic polio (1% to 5% show neurological symptoms such as sensitivity to light and neck stiffness).
- A severe, debilitating form called paralytic polio (this occurs in 0.1% to 2% of cases).
Contagiousness:
Polio is transmitted primarily through the ingestion of material contaminated with the virus found in stool. The polio virus lives in the throat and intestinal tract of infected persons. The virus enters the body through the mouth, usually from hands contaminated from an infected person, or not washing hands after using the bathroom and drinking contaminated water are common culprits in the transmission of the disease.
Duration:
Although the acute illness usually lasts less than 2 weeks, damage to the nerves could last a lifetime. In the past, some patients with polio never regained full use of their limbs, which would appear withered. Those who did fully recover might go on to develop post-polio syndrome (PPS) as many as 30 to 40 years after contracting polio. In PPS, the damage done to the nerves during the disease causes an acceleration of the normal, gradual weakness due to aging.
Prevention:
Two types of the polio vaccine are available: oral polio vaccine (OPV) and inactivated polio vaccine (IPV).
OPV is made with a live, but weakened, virus. OPV protects vaccinated persons directly. OPV also protects other susceptible persons who care indirectly vaccinated as the vaccine spreads in the community. Because of wide spread OPV no cases of paralytic polio caused by naturally circulating polio virus have been reported in the United States since 1979.
As of January 1997, the recommended schedule for polio vaccination for children was two doses of IPV at 2 and 4 months of age, followed by two doses of OPV at 12-18 months and 4-6 years. This schedule is expected to reduce the small number of polio cases caused by the oral vaccine.
Booster doses of polio vaccine are also recommended for persons traveling to areas of the world (Afghanistan, Egypt, India, Nigeria, and Pakistan) where polio is still a problem.
