Central Kentucky hit with mysterious E. coli outbreak

Officials for the Kentucky Department for Public Health (DPH) said 20 Kentuckians – most of whom reside in central Kentucky – have tested positive for E. coli, and six victims have been hospitalized.

The DPH said it has not identified the source of the outbreak but noted that some sort of food distribution is the likely cause. The strain of E. coli causing the illnesses is E. coli O103, which produces a type of toxin (Shiga toxin) that can be dangerous. (There are numerous types of Shiga-toxin-producing [STEC] E. coli.)

“Exposure to E. coli bacteria can be debilitating and potentially life-threatening, especially for small children and individuals with weakened immune systems,” DPH commissioner Dr. Jeff Howard said. “With this in mind, the Department for Public Health has taken swift action to identify patients, ensure appropriate testing, and follow-up care as we work to determine the source of the outbreak.”

Howard said health-care providers throughout Kentucky have been notified and have been advised to be alert for patients experiencing acute diarrhea. He said testing will need to be performed to determine which cases are outbreak-related.

“… we encourage all Kentuckians to be aware of the signs and symptoms of E. coli illness and to seek care if they are ill,” Howard said.

Central Kentucky outbreak:
E. coli symptoms

Symptoms of an E. coli illness are similar to those of other types of food poisoning, and usually include the following:

The Centers for Disease Control and Prevention (CDC) website shows that the federal organization investigated three E. coli outbreaks last year. Two of those were produced by contaminated romaine lettuce, and the other was produced by contaminated ground beef.

The STEC that caused both romaine lettuce outbreaks was – not surprisingly – E. coli O157, which is the most commonly identified type of STEC. In the ground beef outbreak, the STEC was E. coli O26.

Compared with STEC O157 infections, identification of non-O157 STEC infections – like E. coli O103 – is more complex. First, laboratories must test stool samples for the presence of Shiga toxins, and then the samples must be sent to public health laboratories to look for non-O157 STEC. (Clinical laboratories typically cannot identify non-O157 STEC.)

Central Kentucky outbreak:
Timeline of an E. coli outbreak

On its home page for E. coli, the CDC links to a page that outlines the process of investigating an E. coli outbreak. Here is that process:

Determine STEC

To determine the type of STEC, laboratories perform a kind of “DNA fingerprinting” on lab samples. Investigators determine whether the DNA pattern of E. coli bacteria from one person is the same as that from others in an outbreak. They also determine if the bacteria is the same as that taken from the contaminated food.

Bacteria with the same “DNA fingerprint” more than likely came from the same source. Officials will then conduct an investigation, including interviews with those sickened, to determine if there is a common-source outbreak.

Time to illness

Document the incubation period of the illness. This is the time from when a person is exposed to E. coli to the beginning of symptoms, usually one to three days.

Time to contact with doctor

Document the time from the first symptom until a person sees their doctor, when a stool sample is collected for laboratory testing, usually one to five days.

Time to diagnosis

Document the time from when a person gives a stool sample to when E. coli is detected. This can take up to three days from the time the sample is received by the technician. The diagnosis of E. coli infection is usually reported to the local health department.

Transfer E. coli sample

Ship the sample from the laboratory to public health authorities, who then perform “DNA fingerprinting.” This can take up to a week, depending on transportation arrangements within a state and the distance between the laboratory and public health department.

Fingerprinting the DNA

The time required for public health authorities to perform “DNA fingerprinting” on the E. coli sample and compare it with the outbreak strain can be done in a day, but because many public laboratories have limited staff and space and experience numerous situations at the same time, it can take up to four days.

Add it all up, and the time from the beginning of an illness to the confirmation that the illness is part of an outbreak is two to three weeks. That’s why case counts during an outbreak investigation are considered “preliminary” and almost always increase over time.