The countries include Ethiopia, Finland, and Israel.
Poliovirus has been spreading in dozens of countries, the U.S. Centers for Disease Control and Prevention said in a March 3 travel warning.
People planning trips to more than 30 countries, including some in Europe, should be aware of the circulation of the virus, the CDC said.
Poliovirus causes polio, which has no cure and can cause symptoms including paralysis.
The CDC issued a level two warning urging travelers to take enhanced precautions, including ensuring they are up to date on polio vaccines before traveling to any of the countries.
The CDC recommends people receive four doses of a polio vaccine, starting at 2 months of age. That recommendation was kept in place when health officials recently scaled back guidance for some other vaccines.
Adults who have never been vaccinated against polio are generally advised to receive three doses. The second dose should be one to two months after the first. The third dose should be six to 12 months after the second.
Even if people have received a full series, they can receive a booster shot before traveling to a country with polio, according to the CDC. There are standalone polio vaccines and combination shots that include polio.
No other precautions were listed by the CDC in its warning.
Poliovirus spreads mainly through contact with contaminated feces or respiratory droplets from infected persons.
The polio vaccine is highly effective in protecting against poliovirus and paralytic polio, according to the CDC’s Pink Book. At least 99 percent of vaccine recipients are immune after three vaccine doses, the document says.
People should not take a polio vaccine if they have had a severe allergic reaction to a vaccine component or to a prior dose of the vaccine, according to the CDC. The vaccine contains trace amounts of the antibiotics streptomycin, neomycin, and polymyxin B, among other ingredients.
Adverse events recorded following polio vaccination include fever, loss of appetite, and death, according to regulatory documents. Vaccination can also, in rare cases, cause vaccine-associated paralytic polio.
The destinations where poliovirus has been detected within the past 12 months, according to the CDC, are Afghanistan, Algeria, Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Côte d’Ivoire, Democratic Republic of Congo, Djibouti, Ethiopia, Finland, Gaza, Germany, Ghana, Guinea, Israel, Niger, Nigeria, Pakistan, Papua New Guinea, Poland, Senegal, Somalia, South Sudan, Spain, Sudan, Tanzania, the UK, Yemen, and Zimbabwe.
