Salmonella species cause diarrhea and systemic infections, which can be fatal in particularly susceptible persons, such as the immunocompromised, the very young and the elderly. Animals used for food production are common carriers of Salmonella, which can subsequently contaminate foods such as meat, dairy products and eggs. Foods often implicated in outbreaks include poultry and poultry products, meat and meat products, dairy products, egg products, seafood and fresh produce. An estimated 800,000 to four million infections occur every year in the U.S., most of them as individual cases apparently unrelated to outbreaks. Between 128,000 and 640,000 of those infections are associated with Salmonella enteritidis in eggs. Over the past decade, more than 500 outbreaks have been attributed to S. enteritidis, with more than 70 deaths. In 1994 an estimated 224,000 people became ill from consuming ice cream in one outbreak alone.

Campylobacter

The bacterium Campylobacter is the most frequently identified cause of acute infectious diarrhea in developed countries and is the most commonly isolated bacterial intestinal pathogen in the U.S.. It has been estimated that between two and four million cases of campylobacteriosis occur every year with an associated 120 to 360 deaths. Campylobacter jejuni and C. coli (two closely related species) are commonly foodborne and are the infectious agents most frequently described in association with Guillain-Barr¿ syndrome, as frequently as one in 1,000 cases. Several prospective studies have implicated raw or undercooked chicken as major sources of C. jejuni/coli infections. Unpasteurized milk and untreated water have also caused outbreaks of disease.

Toxin-producing Escherichia coli

Several strains of the bacterium E. coli cause a variety of diseases in humans and animals. E. coli O157:H7 is a type associated with a particularly severe form of human disease. E. coli O157:H7 causes hemorrhagic colitis, which begins with watery diarrhea and severe abdominal pain and rapidly progresses to passage of bloody stools. It has been associated with HUS, a life-threatening complication of hemorrhagic colitis characterized by acute kidney failure that is particularly serious in young children. E. coli O157:H7 is found in cattle, but there may be other reservoirs; the dynamics of E. coli O157:H7 in food-producing animals are not well understood. Approximately 25,000 cases of foodborne illness can be attributed to E. coli O157:H7 every year, with as many as 100 deaths resulting. E. coli O157:H7 outbreaks have recently been associated with ground beef, raw milk, lettuce, and minimally processed and fresh fruit juices. The most recent outbreak in the fall of 1996 in three western states and British Columbia was associated with unpasteurized apple juice and sickened 66 people, causing the death of one child.

Vibrio

Vibrio species are gram-negative bacteria most commonly associated with seafood-containing dishes. Vibrio parahaemolyticus is the species most commonly reported as a cause of foodborne disease; it generally causes watery diarrhea and abdominal pain lasting one to seven days and commonly follows consumption of improperly handled, cold seafood salads. V. vulnificus is one of the more serious foodborne pathogens, with a case fatality rate for invasive disease that exceeds 50 percent. Most cases of foodborne V. vulnificus infections occur in persons with underlying illnesses (particularly liver disorders) who eat raw mollusks. Since the late 1980s, the Food and Drug Administration, the Centers for Disease Control and Prevention, and the Gulf Coast states have intensified efforts to collect information on vibrio infections and on the microorganisms' ecology, to improve our ability to prevent foodborne infections.