Campylobacter enteritis: a large outbreak traced to commercial raw milk

Area of Science:

• Foodborne illness epidemiology
• Microbiology
• Public health

Background:

• Campylobacter jejuni is a leading cause of bacterial gastroenteritis worldwide.
• Unpasteurized (raw) milk is a potential vehicle for transmitting foodborne pathogens.
• Previous outbreaks have been associated with contaminated dairy products.

Purpose of the Study:

• To investigate an outbreak of enteritis in Arizona.
• To identify the source and transmission route of Campylobacter jejuni.
• To assess the association between raw milk consumption and diarrheal illness.

Main Methods:

• Two cohort studies were conducted.
• Case and control households were identified based on raw milk consumption.
• Campylobacter jejuni isolates were serotyped.
• Milk and milk filters were cultured for Campylobacter.
• Fecal excretion of Campylobacter in dairy herds was assessed.

Main Results:

• Approximately 200 cases of Campylobacter jejuni enteritis occurred.
• Raw milk consumption was significantly associated with diarrheal illness (P=.003 and P=.001).
• A single serotype of C. jejuni predominated in human isolates.
• Higher fecal excretion of Campylobacter was observed in the implicated dairy herd (48%) compared to controls (16%).

Conclusions:

• Unpasteurized milk from a specific dairy was the likely source of the outbreak.
• Raw milk consumption poses a significant risk for Campylobacter jejuni infection.
• Dairy herd health and milk pasteurization are critical for preventing such outbreaks.