Seasonal Trends in Foodborne Illness: Summer vs. Winter Patterns
Foodborne illnesses in the United States exhibit distinct seasonal patterns depending on the type of pathogen involved. According to the CDC, norovirus, which accounts for 58% of foodborne illnesses, peaks during the winter months, particularly from December to March. This makes winter the season with the highest total case volume when all pathogens are considered. However, bacterial and parasitic pathogens such as Salmonella, Campylobacter, Listeria, and Cyclospora show a strong summer peak, driven by factors like warm temperatures, outdoor cooking, and increased consumption of raw or undercooked foods. Vibrio infections, often linked to raw shellfish, also spike in July and August. While summer is the peak season for many severe bacterial and parasitic infections, the dominance of norovirus in winter skews the overall case count toward colder months. 
