Timeline for Reporting E coli O157:H7 Cases

Posted by Fred Pritzker in Food Safety

When it comes to common source outbreaks of E. coli O157:H7 — regardless of whether the vehicle of transmission is ground beef, fresh produce, raw milk or fruit juice — the time from the beginning of the patient’s illness to the confirmation that he or she is part of an outbreak is typically about 2-3 weeks.

This is important when considering case counts in the midst of an outbreak investigation. Public health officials will sometimes announce an outbreak even if there are only one or two confirmed matches between a food source and an illness.

If officials say the investigation is continuing, usually that means the number of confirmed cases in an outbreak will grow because of the lag time between a person consuming the bacteria and health officials positively confirming an outbreak case of E. coli O157:H7 through DNA fingerprinting.

According to the Centers for Disease Control and Prevention (CDC), here’s a breakdown of the timeline and how long each step can take:

• Incubation time: The time from eating the contaminated food to the beginning of symptoms. For E. coli O157, this is typically 3-4 days.
• Time to treatment: The time from the first symptom until the person seeks medical care, when a diarrhea sample is collected for laboratory testing. This time lag may be 1-5 days.
• Time to diagnosis: The time from when a person gives a sample to when E. coli O157 is obtained from it in a laboratory. This may be 1-3 days from the time the sample is received in the laboratory.
• Sample shipping time: The time required to ship the bacteria from the laboratory to the state public health authorities that will perform “DNA fingerprinting”. This may take 0-7 days depending on transportation arrangements within a state and the distance between the clinical laboratory and public health department.
• Time to “DNA fingerprinting”: The time required for the state public health authorities to perform “DNA fingerprinting” on the E. coli O157 and compare it with the outbreak pattern. Ideally this can be accomplished in 1 day. However, many public health laboratories have limited staff and space, and experience multiple emergencies at the same time. Thus, the process may take 1-4 days.

Tags: E. coli hus, food poisoning