- Polio is a viral infection occurring in Afghanistan, Nigeria, and Pakistan and acquired primarily through consumption of fecally contaminated food or water.
- Risk is very low for travelers going to affected countries, regardless of immunization status.
- Symptoms include fever, sore throat, and gastrointestinal upset. Headache, neck, back, and leg stiffness may also occur.
- Consequences of infection include permanent limb or respiratory muscle paralysis and death.
- Prevention includes observing standard food and beverage precautions and frequent, thorough handwashing.
- Inactivated (killed) polio vaccine (IPV) is routinely given at ages 2, 4, and 6 to 18 months and then at age 4 to 6 years. Completely unvaccinated at-risk adults may need an entire series and every effort should be made to complete the series. However, even a single dose is beneficial.
- Vaccine side effects are most commonly injection-site reactions such as pain and redness.
- A single, one-time adult booster dose is recommended for travel to risk areas, even in those who have had the complete childhood series.
Polio, a highly infectious viral disease that affects the nervous and muscular systems, is acquired through consumption of fecally contaminated food or water. Humans are the only known reservoir of the polio virus. Most infections have no symptoms or are mild; complete recovery seldom occurs in persons who develop muscular and nervous system complications. No drugs or treatments that cure polio are available.
Polio has been eradicated from most countries but still occurs in Afghanistan, Nigeria, and Pakistan. A small number of other countries periodically report circulation of vaccine-derived polio viruses, which may also cause polio disease.
In risk areas, poliovirus is predominantly transmitted through consumption of fecally contaminated food or water or via the oral-to-oral route from saliva or throat secretions of infected persons. Transmission occurs throughout the year in the tropics but peaks in the summer in temperate climates.
Risk to travelers is low and even completely unvaccinated travelers going to a country where polio is still circulating have almost no risk of acquiring clinical polio. Children are most commonly affected in endemic countries.
Symptoms may appear 7 to 10 days following exposure with mild cases causing fever, sore throat, gastrointestinal disturbances, or influenza-like symptoms, with recovery within a week. More serious cases result in headache and stiffness of neck, back, legs, throat, and chest muscles.
Consequences of Infection
Polio can result in difficulty swallowing and breathing, muscular disability, permanent limb paralysis, or fatal respiratory paralysis. Death occurs in about 2% to 75% of symptomatic cases.
Need for Medical Assistance
Unimmunized travelers who develop symptoms of polio during travel to or return from countries where polio still occurs should seek urgent medical assistance.
Observe food and beverage precautions and hand-hygiene (frequent, thorough handwashing) measures; see Food and Beverage Precautions.
An inactivated (killed) polio vaccine (IPV) is available in the U.S. and is given routinely as a childhood vaccination and to certain at-risk travelers. Combination vaccines are also available. Live oral polio vaccine (OPV) is no longer available in the U.S. (although it is still used in some countries).
The most common vaccine side effects are local reactions (pain or redness) at the injection site.
Persons with underlying medical conditions or who have concerns about the vaccine should speak to their health care provider before vaccine administration.
IPV is given as follows:
- Routine, regardless of travel, for children younger than 18 years: 3 doses, at ages 2, 4, 6-18 months; a fourth dose at school entry or at age 4-6 years.
- Previously unvaccinated adults traveling to risk countries who are 18 years and older: 3 doses at 0, 1-2, and 6-12 months after the second dose. If earlier protection is needed for travel: Efforts should be made to complete the series prior to travel, but even a single dose is beneficial.
- Adults traveling to risk countries, Hajj/Umra pilgrims from a risk country who have a completed childhood vaccination but no history of an adult booster, or those needing to meet a destination-country entry requirement: single dose booster. More than 1 lifetime adult booster is unnecessary unless given to meet a destination entry requirement, in which case the booster must be given between 4 weeks and 1 year of departure from the origin country.
- Residents of or long-stay (more than 4 weeks) visitors in Afghanistan, Nigeria, or Pakistan who are onward travelers to other countries, if they have not received 1 additional dose of polio vaccine between 4 weeks and 1 year of departure from the country (regardless of primary series completion): single-dose booster
Revaccination with an IPV primary series may be needed for a child who had been vaccinated with a routine OPV series outside the U.S.
Persons younger than 18 years who received their last childhood dose 10 or more years previously should receive the adult booster.
Vaccination is required for:
- Hajj and Umra pilgrims traveling to Saudi Arabia (regardless of age and vaccination status) coming from countries on a defined list of suspected polio-endemic countries and countries at high risk for reimportation of polio.
- Travelers going to certain polio-free countries that have an entry requirement for travelers (residents or long stay visitors) coming from countries on a defined list of suspected polio-endemic countries.