A strange outbreak was announced this month by the FDA and CDC. At least 22 people were sick with five rare and very similar strains of Listeria monocytogenes; 22 of them were hospitalized. That’s not uncommon, but here’s the weird part: those illnesses began in 2010.
Government officials investigated, and found that 83% of those patients reported eating soft cheeses in the month before they got sick. Further investigation found that four of seven ill people specified a brand of soft cheese distributed by Karoun Dairies of San Fernando, California.
Whole genome sequencing (WGS) analysis of two environmental samples collected by the FDA showed Listeria monocytogenes bacteria that is “highly related” to the outbreak strains found in sick people. Those samples were collected at Central Valley Cheese facility in Turlock, California. Central Valley manufactures cheese for Karoun Dairies. More WGS analysis found that five environmental samples collected from the Central Valley facility in 2010 were also highly related to the outbreak strains. Which means that Karoun Dairies cheeses are the likely source of this outbreak.
The CDC report states that fifteen of the 24 people sickened were of Middle Eastern or Eastern European descent or shopped at Middle Eastern-style markets. Some of Karoun’s cheeses are quite unusual, including ani, kefir, feta, Middle Eastern-style string cheese, village cheese, and nabulsi. Patients identifying those cheeses made narrowing down the source of the bacteria much easier, so the mystery was solved.
But with cases going back so far, our question is: are people who are part of this outbreak told about it? Food poisoning infections are quite memorable simply because you can be so sick, and most people would certainly remember having a Listeria infection. But how do you know if you are part of this outbreak?
We contacted health departments in all of the nine states where patients lived (plus Minnesota), and got some interesting responses. It turns out that whether outbreak members are contacted depends on the state where they live.
Epidemiologist Amy Saupe from the Minnesota Department of Health (MDH) told us that in Minnesota, people are usually interviewed several times during an outbreak. Most cases are called back with more questions, but people are not identified and notified when an outbreak is discovered. She said that general methods for notification differ by state.
In Michigan, Jennifer Eisner, Public Information Officer, said that officials forward the outbreak information to the local health department where the patient lives. The local health department was told about this particular outbreak, recall, and the CDC report as soon as state officials knew about it, but it was then up to the local health department to contact the patient.
Woody McMillin, Director of Communications and Media Relations of the Tennessee Department of Health said, “we reach out to all Listeria cases to interview them. In this circumstance we would not reach back out to the ill person unless we needed to ask additional questions. We do notify people in some circumstances when we are investigating an outbreak but that is typically during active investigations.”
The Colorado Department of Public Health and Environment lets current patients know that they are part of an ongoing outbreak, according to Mark Salley, Communications Director. The case in Colorado occurred this year so that patient is aware of the outbreak. He said there isn’t a formal process for alerting previously ill persons about their links to outbreaks.
Melani Amato, Public Information Officer of the Ohio Department of Health, said that Ohio’s case was from some years ago, and that patient died. She said that after the initial interview, that DOH does not usually contact patients again unless they can provide a public health response.
Ronald Owens of the California Department of Public Health’s Office of Public Affairs told us that CDPH notifies local public health departments of case-patients that are associated with an outbreak. CDPH does not usually communicate directly with case-patients. He added that in most cases doctors would not know that a patient is linked to an outbreak. Mr. Owens also said that this outbreak was identified through whole genome sequences methods, which were not available in 2010.
Omar Cabrera from the Communications Office at the Department of Public Health in Massachusetts said that they do not do follow ups with old cases unless the CDC needs additional information from that person. He said that they may need to call someone back to find out epidemiological issues, such as the foods they ate or places they have been. Sometimes they do inform someone who is part of a multistate outbreak.
Amy Saupe of the MDH added that the CDC cannot let people know they are part of an outbreak, since the federal government doesn’t have access to private data such as case names and contact information. In addition, most state health departments don’t have the resources to re-contact everyone who is part of an outbreak.
The patient’s doctor would usually be unable to tell a person they are part of an outbreak because they don’t have access to sub typing information or other details about the outbreak, according to Saupe. But, patient information is kept by state or local health departments.
So. If you had a Listeria monocytogenes infection in the last five years and ate soft cheeses from Karoun Dairies, you can contact your state or local health department to ask if you are part of this outbreak. The symptoms of listeriosis include flu-like fever and muscle aches, upset stomach or diarrhea, stiff neck, headache, and loss of balance. Pregnant women are especially susceptible to this infection; in fact, one woman in this outbreak sadly suffered a miscarriage.