What is the most common cause of bacterial diarrhea in the U.S.?

The most common cause of bacterial diarrhea in the U.S. is Campylobacter jejuni. This bacterium is frequently associated with foodborne illness and is particularly linked to undercooked poultry, unpasteurized milk, and contaminated water. Infection typically presents with symptoms such as diarrhea, cramping, fever, and sometimes vomiting, which align with the common presentation of bacterial gastroenteritis.

While other bacteria, such as Escherichia coli, Salmonella Typhi, and associated Salmonellosis (which refers to infections caused by the Salmonella species), can also cause diarrhea, they are not as prevalent in terms of incidence compared to Campylobacter jejuni. Escherichia coli, particularly certain strains like O157:H7, can cause severe foodborne illness but is less frequently the leading cause overall. Salmonella Typhi is primarily responsible for typhoid fever, a more severe illness that is not as common as the gastrointestinal infections caused by Campylobacter jejuni. Salmonellosis includes a broader category of infections caused by various species of Salmonella, yet Campylobacter jejuni remains the most common individual bacterial pathogen responsible for diarrhea in the population.