Polio is a viral infection that is most commonly associated with paralysis of children and contributes to morbidity of adulthood. Fortunately, an effective vaccine exists to prevent Polio and is generally given with the routine shots of childhood. Some adult travelers should receive a booster vaccine, especially before international trips.
Basics: A viral infections that effects the gastrointestinal tract and can rarely spread to the central nervous system. Paralysis occurs in less than 1% of infections and the majority are unnoticed or feature a non-specific fever. The paralysis of polio is usually flaccid (weak) and aasymmetric (one side of the body). Legs are more commonly effected that arms. This infection is shed in the feces of infected persons and communicated to others in a fecal-oral route. The vast majority of cases occur in children less than 5 years of age.
Locations: Prior to widespread vaccination, polio was found world-wide. Wild type or naturally occurring polio is decreasing due to massive campaigns to vaccinate and as of 2002 was endemic in 7 countries: Afghanistan, Egypt, India, Niger, Nigeria, Pakistan and Somalia. During 2002 89% of wild type polio was found on the Indian sub-continent and 11% in West Africa. Although localized in geographic clusters, importation of disease to developed nations is still very possible. A large outbreak in 1992-1993 occurred in the Netherlands, among a specific religious group who refused the vaccine.
Polio Vaccine: Two main types of polio vaccines exist. Oral Polio Vaccine (OPV) and Inactivated Poliovirus (IPV) are the two options for polio prevention. The IPV vaccine is used in the USA and is given as an injection. OPV is commonly used in developing nations and is taken orally, as a liquid. Both vaccines are highly effective. The OPV type can cause vaccine associate paralytic polio (VAPP) at a rate of approximately 1 in 2.4 million. This reason was why most nations have switched to the injectable form. Still, OPV is the vaccine of choice for global eradication due to its effectiveness against wild-type polio and lower number of doses required.
Recommendations for Adults: Most adults living in America, Europe and Australia have received their primary series in childhood and are immune to polio. The CDC discusses adults who travel to an area where wild type polio is know to be transmitted and their need for a single IPV vaccine, as a booster. This is a one time booster, for the life of the traveler. More can be read here: http://wwwn.cdc.gov/travel/yellowbook/2008/ch4/poliomyelitis.aspx