Listeria and moms-to-be

Giving food safety – or any – advice to pregnant women is fraught with angst. And probably a lot of hypocrisy if you’re a dude.

I don’t want to freak anyone out, especially expectant mothers, but also have a responsibility to share accurate, evidence-based information if I know something about, say, food safety.

The certainties of youth left me long ago.

But certainties were on full display in an article distributed by the Australian Associated Press on April19, 2011, entitled, Pregnancy diet overkill.

Among the nosestretchers offered up by dietician and author Tara Diversi, quoted in the AAP story (I’ll put quotes from Tara or the story in italics, with a bullet, and my responses in something other than italics; and the comments at the bottom from NSW Food Authority will be in italics):

• "It’s not that you’re at higher risk (of food poisoning) being pregnant."

No. A Dec. 2007 review of listeria in pregnancy states,??“One of the most important changes during pregnancy is the down-regulation of the cellular immune system. Because the fetus is genetically different from the mother, the body treats it as a graft. To prevent the maternal immune system from rejecting the fetus, cell-mediated immunity must therefore be suppressed during pregnancy. This is favored by high levels of progesterone. However, reduced cell-mediated immune function leads to increased susceptibility of the woman and her fetus to infections by intracellular pathogens such as Listeria monocytogenes. That is why pregnant women are 20 times more at risk of contracting listeriosis than are other healthy adults. Pregnant women account for 30% of all cases of listeriosis and 60% of cases among persons 10 to 40 years of age.??“Typically, systemic infection occurs most frequently after ingestion of food contaminated with L monocytogenes. The bacteria cross the mucosal barrier of the intestine, probably aided by active endocytosis of organisms by epithelial cells. Once in the bloodstream, bacteria spread to different sites, but they have a particular affinity for the central nervous system or placenta. While circulating, the bacteria are internalized by macrophages and other plasma cells and are thereafter spread cell-to-cell through phagocytosis. As a result, antibodies, complement, and neutrophils become unable to protect the host.”

Pregnant women are about 20 times more likely than other healthy adults to get listeriosis. About a third of all reported cases in Illinois happen during pregnancy. Infection during pregnancy may result in spontaneous abortion during the second and third trimesters, or stillbirth.

The advice from the U.S. Centers for Disease Control is clear: Do not eat hot dogs, luncheon meats, or deli meats, unless they are reheated.

It has been documented that many pregnant women are not aware of the risks associated with consuming refrigerated, ready-to-eat foods like cold cuts.

Researchers reported in the Australian and New Zealand Journal of Health that in a survey of 586 women attending antenatal clinics in one private and two major public hospitals in New South Wales between April and November 2006, more than half received no information on preventing Listeria.

• But who would have thought the humble alfalfa sprout could be a cold-blooded killer in disguise?

Outbreaks of foodborne illness related to raw sprouts happen frequently. A table of North American raw sprout-related outbreaks is available at

• Diversi says there hasn’t been a reported incident of poisoning from undercooked eggs since 1970s. "(Some of the advice) is weird. It’s not like we’re a Third World country," she says.

No. Hundreds of people have been sickened in Australia in the past five years from consuming undercooked eggs or dishes containing raw eggs, including 111 sick with salmonella from home-made aioli — a garlic mayonnaise that includes raw egg – at the Burger Barn in Albury, Australia last year. Other Australian outbreaks are available at these links.

• "It’s hard, because as a dietitian you don’t want to give blanket advice. But if I were pregnant myself I would eat poached eggs and I would eat from salad bars and I would eat lean meats because I know that they’re going to give me energy and the likelihood of getting food poisoning from it is relatively low. The trick is to limit the risks by buying your lunch from a reputable place with a high turnover.”

No. This sounds suspiciously like the terrible and libelous advice issued by the Motherisk team last year at Toronto’s Hospital for Sick Children, in which they stated,

“pregnant women need not avoid soft-ripened cheeses or deli meats, so long as they are consumed in moderation and obtained from reputable stores.”

I have no idea what a reputable source is. Certainly doesn’t have anything to do with microbiology.

Fortunately, the folks in Sydney at the New South Wales Food Authority comprehend some risk communication basics and fired out their response within a day. Excerpts below:

In its role as Australia’s first and only through-chain food regulatory agency the NSW Food Authority is responsible for providing consumers with safer food and clearer choices.

The Authority maintains a segment on its website dedicated to pregnancy and food safety.

It clearly states the best way to meet you and your baby’s nutritional needs is to eat a wide variety of nutritious foods.

These should include:
• bread, cereals, rice, pasta & noodles preferably wholegrain or wholemeal
• vegetables & legumes
• fruit
• milk, yoghurt, hard cheese preferably low fat
• meat, fish, poultry, cooked eggs & nuts.

The Authority provides information about how best to enjoy those foods safely, what foods to avoid during pregnancy and provides alternatives to foods identified as having a higher risk of containing certain bacteria that could be harmful to pregnant women and their unborn babies.

The Authority provides information on Listeria to pregnant women to allow them to make an informed food choice regarding the risk and how to minimise it. It is not to say that every piece of deli meat has Listeria on it, but some foods have a higher potential rate of contamination than others, and it is better to avoid them.

The risk of acquiring listeriosis is low. However the consequences for a pregnant woman contracting listeriosis are dire.

While the Authority may be accused of ‘being over the top’, we may also be accused of neglecting pregnant women if we did not provide this information so pregnant women could make informed choices in what they eat.

Over the last 5 years in Australia there have been between 4 and 14 cases of listeriosis diagnosed in pregnant women or their babies each year. These infections have resulted in the deaths of 8 foetuses or newborn babies.

Rates of listeriosis are increasing in Europe including France where they have increased over the last five years.

Listeriosis rates in France are twice that of Australia.

Language a ‘risk factor’ for listeria in Australia

Focusing on the language needs of expectant mothers and enhancing food safety in hospitals could reduce cases of foodborne illness caused by listeria.

Australian researchers report in the current Epidemiology and Infection that of 136 cases of listeriosis in Australia between Nov. 2001 and Dec. 2004, 40 per cent of cases with prior hospitalization were exposed to high-risk foods during hospitalization; consumption of camembert cheese was an additional risk factor.

Of the 19 perinatal cases — defined as illness in a pregnant woman, fetal loss, or illness in a baby aged less than 3 months with isolation of L. monocytogenes from at least one of the maternofetal pair — living in a household where a language other than English (LOTE) was spoken was the primary risk factor associated with listeriosis.

The numbers are small, but the researchers have identified a persistent problem – providing information is nice, but what if the target can’t read or understand (in this case) English?

“The Food Standards Australia and New Zealand (FSANZ) website only provides a brochure on listeriosis and food in English. Languages used in State and Territory brochures vary widely with some only including English while others provide up to 14 languages other than English.

“This study identified that listeriosis prevention messages need to be disseminated in multiple languages and primary-care practitioners should ensure that patients from households speaking a LOTE receive counselling on listeriosis prevention.”

Which sounds nice, but since hospitals are serving high-risk foods to others at risk, maybe the medical community is a limited source of information. And just because a brochure is in another language doesn’t mean anyone will read it or act upon the information. That requires far more rigorous evaluation in terms of information needs, delivery, messages and accuracy. The morons at Toronto Sick Kids hospital told moms-to-be that cold-cuts and raw fish were OK (they’re not).

As the authors conclude,

“The effectiveness of the implementation of the new food safety programs for food service to vulnerable persons should be carefully evaluated to ensure optimal protection of this group.”

A national case-control study of risk factors for listeriosis in Australia
Epidemiology and Infection (2011), 139: 437-445
C.B. Dalton, T.D. Merritt, L.E. Unicomb, M.D. Kirk, R.J. Stafford, K. Lalor and the OzFoodNet Working Group
Listeriosis is a foodborne disease associated with significant mortality. This study attempts to identify risk factors for sporadic listeriosis in Australia. Information on underlying illnesses was obtained from cases’ treating doctors and other risk factors were elicited from the patient or a surrogate. We attempted to recruit two controls per case matched on age and primary underlying immune condition. Between November 2001 and December 2004 we recruited 136 cases and 97 controls. Of perinatal cases, living in a household where a language other than English was spoken was the main risk factor associated with listeriosis (OR 11·3, 95% CI 1·5–undefined). Of non-perinatal cases we identified the following risk factors for listeriosis: prior hospitalization (OR 4·3, 95% CI 1·0–18·3), use of gastric acid inhibitors (OR 9·4, 95% CI 2·4–37·4), and consumption of camembert (OR 4·7, 95% CI 1·1–20·6). Forty percent of cases with prior hospitalization were exposed to high-risk foods during hospitalization.


Really big nosestretcher alert: leading Toronto hospital says cold cuts, raw fish, OK for expectant mothers

Erin Stadler was at her baby shower in North Carolina in 1997 when she at a piece of brie cheese that was contaminated with listeria. The disease made Stadler and her unborn child deathly ill.

"You don’t think about eating one piece of cheese and almost dying. That’s basically, what happened for both of us," said Stadler.

When Stadler went to the hospital, doctors immediately delivered baby Allison. She was premature at 33 weeks. Allison was in the hospital for two more weeks for additional tests when doctors realized how ill both Erin and Allison were.

Two pregnant women on Virgin Blue Australian flights last year gave birth prematurely after being served listeria-laden chicken wraps.

In the fall of 2008, along with the Maple Leaf listeria-in-deli-meat mess, an outbreak of listeria in cheese in Quebec led to 38 hospitalizations, of which 13 were pregnant and gave birth prematurely. Two adults died and there were 13 perinatal deaths.

A Sept. 2008 report showed that of the 78 residents of the Canadian province of British Columbia who contracted listeriosis in the past six years, 10 per cent were pregnant women whose infections put them at high risk of miscarriage or stillbirth.

The majority — nearly 60 per cent — of pregnant women diagnosed with listeriosis either miscarry or have stillbirths.

The authors wrote,

"Health care providers [want] better information for themselves and resources they could share with pregnant women. … The information provided to pregnant women by health care providers needs to be targeted and clear," and that as a result of the spring survey, BCCDC will start a project to better inform health care providers and their patients about food safety risks during pregnancy.

The U.S. Centers for Disease Control and Prevention (CDC) has estimated approximately 2,500 cases of liisteriosis occur annually in the United States, with about 500 cases resulting in death. In 2000, listeria exposure resulted in a higher rate of hospitalization than any other foodborne pathogen and more than one-third of reported deaths from food pathogens.

CDC has a list of foods to avoid while pregnant: deli meats or cold-cuts top the list. Health Canada has similar advice.

Which makes a report in the April 2010 edition of the journal, Canadian Family Physician, absolutely baffling.

Worse, the report was authored by the Motherisk team at the previously reputable Toronto Hospital for Sick Children.

The authors state, correctly, that the incidence of listeria “among pregnant women remains about 20 times higher compared with the general population,” but go on to state, without any references, that “pregnant women need not avoid soft-ripened cheeses or deli meats, so long as they are consumed in moderation and obtained from reputable stores.”

Here is the actual Q&A as printed in the article:

QUESTION After hearing about outbreaks of illness resulting from Listeria and Salmonella, many of my patients are wondering about the risks of food-borne illnesses during pregnancy and what they can do to reduce their chances of contracting them.

ANSWER Although heating or cooking food is the best way to inactivate food-borne pathogens, improved standards and surveillance have reduced the prevalence of contaminated foods at grocery stores. Therefore, it is no longer necessary for pregnant women to avoid foods like deli meats and soft cheeses (associated with Listeria); soft-cooked eggs (associated with Salmonella); or sushi and sashimi. Regardless of whether seafood is raw or cooked, pregnant women should choose low mercury seafood (eg, salmon and shrimp) over higher mercury varieties (eg, fresh tuna). Pregnant women should ensure that their food is obtained from reputable establishments; stored, handled, and cooked properly; and consumed within a couple of days of purchasing.

I have no idea what the authors mean by a reputable source. I have no idea how this advice got approved and published. How is it that the authors, Carolyn Tam, a graduate student in clinical pharmacology at the University of Toronto, Aida Erebara MD, and Adrienne Einarson RN, assistant director of the Motherisk Program could come up with such terrible food safety advice from the 25-year-old Motherisk program which is designed “to ensure the well-being of mothers and babies, worldwide.”

And they want donations.

Someone has already sent the editor a letter of protest.

Thanks to the reader who sent me the link.