The 2026 FIFA World Cup will present one of the most complex infectious disease challenges ever faced by infection preventionists and public health officials. Spanning 3 countries, 16 host cities, and millions of international travelers, the tournament creates opportunities for the spread of respiratory illnesses, foodborne diseases, sexually transmitted infections, vector-borne pathogens, and rare high-consequence diseases. While the matches will last only a few weeks, surveillance efforts will need to continue for months afterward as infections such as tuberculosis and other travel-associated diseases emerge.