I don’t know if I’m a #murderino, but I definitely have My Favorite Murder on my shortlist of podcasts. It’s a nice easy listen when I’ve had too much freakonomics/food safety talk/food job rocks and I’m tired of thinking about complex problems. But they snuck in a nerd snipe when they brought up “Typhoid Mary” (ep. 105). So I figured I’d share this interesting story here, and add a little FF&F regulatory research and risk management sprinkles to really make it as boring as possible.

What’s up my QA peeps. Let’s dig into this.

The setting is the late 1880’s. For those of us who look at these things on the germ-theory timeline, that’s around the time we starting using Koch’s postulates to assign cause-and-effect between microbes and disease, but we’re still trying to get doctors to sanitize their scalpels (we’re still trying to get them to wash their damn hands).

Germ theory timeline
That’s right, I made this and it rocks. Copyright FurFarmandFork 2018.


It starts in the kitchen

Mary Mallon worked as a household cook in Long Island, NY in 1906. During that year, 6/11 people working in her household came down with typhoid fever (caused by Salmonella enterica ser. typhi). An epidemiologist of the day, George Soper, investigated the illnesses and concluded that freshwater clams were to blame. This turned out to be premature, and further digging into Mary’s background showed a disturbing trend. Of the previous 8 families Mary had cooked for, seven of the households had endured typhoid outbreaks, and one child had died.

When confronted by Soper, Mary did not take kindly to requests for bodily fluids or the insinuation that she was making her employers ill. She chased Soper away, apparently with some “vigor”. Soper, being concerned (though more likely driven by scientific curiosity and wanting to publish his find) returned with doctors and police who forcefully subdued her and collected samples at a local hospital, confirming that the apparently asymptomatic Mary was shedding Salmonella typhi. Mary was then given three choices, give up professional cooking, agree to surgery to remove her gall bladder (which they assumed would solve the problem), or live in quarantine on an island in the East River.

I never had typhoid in my life, and have always been healthy. Why should I be banished like a leper and compelled to live in solitary confinement with only a dog for a companion?”

-Mary Mallon

After three years of quarantine and attempting different legal means of escape, Mary struck a deal with the local health commissioner whereby she was released from the island under the agreement that she would not continue cooking as a profession.

On release, Mary disappeared.

In 1915, the Sloan Maternity Hospital in Manhattan had a 25 person typhoid outbreak with two fatalities reported. The Head obstetrician Edward Cragin called Soper to determine if the “Mary Brown” working as a cook there could possibly be the previously quarantined Mary Mallon. Soper confirmed and Mary was collected and returned to North Brother Island without a struggle, where she would remain for the rest of her life.

Education and anecdote

We don’t have Mary Mallon’s side of the story here, but those of us who educate people on food safety and public health can feel a certain familiarity with Soper’s recollection of trying to explain to Mary why these things were happening to her:

You say you have never caused a case of typhoid, but I know you have done so. Nobody thinks you have done it purposely. But you have done it just the same. Many people have been made sick and have suffered a great deal; some have died…specimens taken…proved what I charged. Now you must surely see how mistaken you were. Don’t you acknowledge it? Well, I will tell you how you do it. When you go to the toilet, the germs which grow within your body get upon your fingers, and when you handle food in cooking they get on the food. People who eat this food swallow the germs and get sick. If you would wash your hands after leaving the toilet and before cooking, there might be no trouble.

George Soper

There it is. We understand the science, we have actual sick patients, and we have lab results. However, the employee/restaurant/farmer/company insists that they’ve been making/eating food for years and “no one has gotten sick.” Or that they are being “targeted” by the state. As a food producer however, you are required by the FDA food code and 21 CFR Part 117 to prevent disease carrying personnel from transmitting food-borne illness.

21 CFR 117.10(a)

Any person who, by medical examination or supervisory observation, is shown to have, or appears to have, an illness, open lesion, including boils, sores, or infected wounds, or any other abnormal source of microbial contamination by which there is a reasonable possibility of food, food-contact surfaces, or food-packaging materials becoming contaminated, must be excluded from any operations which may be expected to result in such contamination until the condition is corrected, unless conditions such as open lesions, boils, and infected wounds are adequately covered (e.g., by an impermeable cover). Personnel must be instructed to report such health conditions to their supervisors.

Food Code 2-201.11

The PERMIT HOLDER shall require FOOD EMPLOYEES and CONDITIONAL EMPLOYEES to report to the PERSON IN CHARGE information about their health and activities as they relate to diseases that are transmissible through FOOD. A FOOD EMPLOYEE or CONDITIONAL EMPLOYEE shall report the information in a manner that allows the PERSON IN CHARGE to reduce the RISK of foodborne disease transmission, including providing necessary  additional information, such as the date of onset of symptoms and an illness, or of a diagnosis without symptoms

This can be awkward for a few reasons. Let’s tackle them separately.

Isn’t my medical information confidential?

It is, until it becomes a threat to public health. The key point is that food employers cannot share your information with other people, but employees have to report under various conditions. Guidance for the Americans with Disabilities Act (ADA) states:

May I require a current employee to report whether he has a disease transmissible through food as listed in the FDA Food Code or to fill out Model Form 1-A from Annex 7 of the FDA Food Code?

Yes, you may require current employees to make these reports. The ADA itself recognizes the danger to public health presented by diseases transmissible through the handling of food. See 42 U.S.C. . 12113(d)(1) and (2). The ADA also says that you may follow any state, county or local food handling law designed to protect the public health from the infectious and communicable diseases identified by the CDC. See 42 U.S.C. . 12113(d)(3). Such state, county or local food handling laws may include the Food Code’s reporting requirements.

Therefore, food service employers who follow the FDA Food Code reporting requirements do not violate the ADA. The FDA Food Code reporting requirements are:

  • In section 2-201.11(A), an employee has to report whether he is diagnosed with an illness due to one of the Big 4 listed pathogens.
  • In section 2-201.11(B), an employee has to report whether he has any symptoms relating to intestinal illness, boils or infected wounds.
  • In section 2-201.11©, an employee has to report if he has had a past illness due to one of the listed pathogens.
  • In section 2-201.11(D), an employee has to report if he meets one of the specific high-risk conditions for becoming ill due to one of the four listed pathogens.(6)
  • In section 2-201.13, an employee must get a medical clearance before the employer may lift the employee’s exclusion or restriction.

You may also ask medical questions of a particular employee who handles food if you have an objective factual basis, i.e., concrete reasons, for linking the employee’s medical condition to workplace safety or job performance. For example, if you see that an employee is vomiting or has other symptoms of a gastrointestinal illness, you may ask her if she has one of the Big 4 diseases. You have an objective reason to believe that the employee may pose a risk to workplace safety because you have observed the symptoms that the FDA has determined are likely to transmit one of the listed foodborne illnesses.

CDC mirrors this guidance as well, and restates that the ADA does not supersede public health in food-handling situations, nor does the Health Insurance Portability and Accountability Act (HIPAA) prevent restaurant managers from asking employees about foodborne illness symptoms and diagnoses. Once again, your protections extend to your health information being shared beyond your supervisor and any others who act as the Person-In-Charge at the site, but your employer is not permitted to share this information with other employees or anyone else without your consent.

How would we know?

This is another big one. We see public health alerts all the time for things like Hepatitis A where employees report exposure or illness after the fact. Your best protection here is strictly following the requirements of Part 117, where personnel must be instructed to report such health conditions to their supervisors. In all the hustle and bustle of new hire training, it’s easy to forget to remind people that if they think they got “food poisoning”, “stomach flu”, or any sort of diagnosed “gastroenteritis”, they need to let you know! You can reinforce this with good signage telling employees that they need to stay away from work if they’re sick…but then you have the business challenge…

Yeah, but…are they really sick?

Careerbuilder has done several annual surveys that are conducted online to answer this question, the results aren’t great.

Percent of surveyed employees who have called in to work sick when feeling well in the past year:

2014: 28%

2015: 38%

2016: 35%

2017: 40%

That’s not a great trend to promote employer-employee trust, and a big reason for mixed messages regarding sick leave policies despite the food code requirements. Absenteeism is also a huge employer cost, both in real dollars and opportunity costs. The legal framework regarding how employers can address “too many” sick days changes state to state, and is often determined in employee or union contracts in addition to state law.

Okay, so everyone actually here is probably not the least bit sick then…

CDC surveillance data indicates that food handled by ill workers is a cause of almost half of restaurant related outbreaks, and in a survey with 426 restaurant managers in 2014, they found that 70% of them had worked while ill, and 10% of them had worked while having nausea or “stomach flu.” Workers reported the following most common reasons for coming to work while sick:

  • The restaurant did not offer paid sick leave or have a sick leave policy.
  • The restaurant was shorthanded and no one else could take their shift.
  • They did not feel very sick or thought they would not pass their illness to anyone else.
  • Their sense of duty or strong work ethic.

The research demonstrated that normally it is workers who decide to work when sick. So now you have a second erosion of trust where employees are potentially both pretending to be well, and pretending to be sick. This is all compounded when you also are struggling to establish food safety culture and encourage good manufacturing practices like handwashing, cross-contamination concepts, temperature checks, sanitation….

…it’s amazing we make any progress at all with people like Mary.

But. We. Do.

Honestly, because of the literature I slogged through, this was kind of a depressing post. Then I came upon this article, which has one of the best summaries of consumer perception of food safety in the home I’ve ever seen, and a citation goldmine. Food does continue to get safer year over year. And the authors gave us some advice on reaching people like Mary, so here’s what we need to do:

Share Knowledge

Not everyone is into the data, but education works, and we can keep sharing non-technocratic tidbits. USDA’s Clean, Separate, Chill, and Cook is a great example of a simple campaign that communicates the basics. We can also stop mentioning 5 different temperatures for foods when they ask us for one, and really work to promote kitchen sanitation beyond “throw away your sponges” and start including “clean your fridge when it’s covered in meat juice”. (guilty).

Encourage Responsibility

The majority of news consumers are given regarding food safety are food recalls or outbreaks caused by a supply chain or restaurant, no one is reporting that Dad and the kids had diarrhea last weekend but no one missed work. We can help people understand the control they themselves have by communicating how these supply chain illnesses spread. After all, a piece of chicken full of salmonella is hard-pressed to get you sick if it doesn’t touch your plate or vegetables and gets cooked all the way. Safe food doesn’t have to be a lottery.

It’s not just “stomach flu”

Consumers focus on health dangers they see as 1, potentially affecting them personally and 2, scary. Cancer associated with any activity does an excellent job of clearing the room because people can imagine themselves with a diagnosis, and they know what the ultimate result may be (See prop 65 legislation). Organizations like Stop Foodborne Illness are doing an excellent job of showing people that, in many circumstances, diarrhea isn’t the punchline of a joke any more than cancer is.

Bring them to action

People work well with cues. My wife and I are both food safety people, and because of our knowledge we often take risks with our own food that we would never permit with my 2-year-old nephew. The fresh cilantro raw egg aoli stays at home. We need to identify cues that tell people “wait, something might be unsafe here”. Campaigns USDA has championed around cooking pork and chicken thoroughly have been very effective in this sense, minus the whole poultry washing thing…the more we can “ping” people that a food or action is higher risk (e.g. slicing cantalope or canning), the more they can direct their efforts where they do the most good.


For Mary, it was 1906, we had barely figured out what germs were. 100 years later, we shouldn’t be in the same level of denial. Let’s get to work.





Byrd-Bredbenner, Carol, et al. “Food safety in home kitchens: a synthesis of the literature.” International journal of environmental research and public health 10.9 (2013): 4060-4085.

CDC. Foodborne Diseases Active Surveillance Network (FoodNet): FoodNet 2015 Surveillance Report (Final Data). Atlanta, Georgia: U.S. Department of Health and Human Services, CDC. 2017.

Equal Employment Opportunity Commission. 2014. “How to Comply with the Americans with Disabilities Act: A guide for Restaurants and Other Food Service Employers”.https://www.eeoc.gov/facts/restaurant_guide.html

Norton, D. M., et al. “Managerial practices regarding workers working while ill.” Journal of food protection 78.1 (2015): 187-195.

Radke, Taylor. “Discussing Symptoms With Sick Food Service Employees.” Journal of Environmental Health 80.5 (2017): 24-26.

FDA. 2017 “Food Code”.https://www.fda.gov/downloads/Food/GuidanceRegulation/RetailFoodProtection/FoodCode/UCM595140.pdf

Brooks, Janet. “The sad and tragic life of Typhoid Mary.” CMAJ: Canadian Medical Association Journal 154.6 (1996): 915.

Marineli, Filio, et al. “Mary Mallon (1869-1938) and the history of typhoid fever.” Annals of Gastroenterology: Quarterly Publication of the Hellenic Society of Gastroenterology 26.2 (2013): 132.

Soper GA. The curious career of Typhoid Mary. Bull N Y Acad Med. 1939;15:698–712.