Federal health officials have issued urgent travel advisories for the United Kingdom, Germany, Finland, Poland, and Spain due to the circulation of polio, a highly infectious disease that attacks the nervous system. While most people infected with polio show no symptoms, severe cases can result in muscle weakness, paralysis, and even death if breathing muscles are affected. The virus, which was eradicated from the United States in 1979, has recently been detected in wastewater samples in several countries, raising concerns about silent transmission from asymptomatic individuals. The CDC recommends travelers to these countries ensure they are up to date on polio vaccinations and take enhanced precautions, such as receiving a booster and practicing good hygiene. Polio remains a threat in 39 countries and territories worldwide, despite widespread vaccination efforts.