Food-Borne Hazards
Major food-borne hazards relevant during pregnancy are:
1. Listeriosis 2. Toxoplasmosis 3. Methylmercury
Table 2 Common high-risk foods, their associated food safety risk, and best practices to minimize the risk
High-risk foods
Concerned food
safety risk Food safety practices References
Raw sprouts E. coli O157:H7 Salmonella
Thoroughly cooking [26]
Unpasteurized juice E. coli O157:H7 Salmonella
Make sure juice has been pasteurized or treated enough to kill harmful bacteria; if
unpasteurized then bring it to boil for a minute before consumption
[5, 19]
Unpasteurized milk Listeria monocytogenes, Salmonella, E. coli O157:H7, Campylobacter
Consume pasteurized milk [5]
Dairy products from unpasteurized milk (like soft cheeses, yoghurt, pudding, ice cream or frozen yoghurt)
Listeria monocytogenes, E. coli O157:H7, Salmonella
Use pasteurized milk [5]
Raw or undercooked
‘runny” eggs
Salmonella, Cryptosporidium
Fully cooked eggs with firm yolk and white; avoid raw/undercooked eggs and products from them like homemade mayonnaise and salad dressings, custards, ice cream, raw cookie dough and egg batter
[5, 27]
Raw/undercooked meat/poultry
Clostridium perfringens, Campylobacter, E. coli O157:H7
Cook to a safe minimum internal temperature
[5]
Raw/undercooked fish/
shellfish/sushi
Campylobacter, Vibrio vulnificus, Norovirus, Salmonella
Use/consume fully cooked fish (cook till 145 °F) or sea food;
limit consumption of high mercury shellfish and fish (including tuna, yellowtail). Low mercury alternatives like salmon, crab, and shrimp can be consumed more regularly
[5, 27]
Apart from these, Salmonellosis, Campylobacteriosis, and contamination with Cryptosporidium, Clostridium perfringens, Escherichia coli O157:H7, Norovirus, and Vibrio vulnificus can also occur in pregnant women and cause food-borne illness [5]. Since listeriosis and toxoplasmosis are most likely to affect pregnant women due to unsafe food-handling practices, we will discuss these two in detail.
Listeriosis
Listeriosis is a type of food-borne hazard that occurs because of ingestion of food contaminated with Listeria monocytogenes. Approximately 1600 illness and 260 deaths due to listeriosis occur annually in the United States [28]. Listeriosis has been a major issue as a food-borne illness although it is uncommon but potentially fatal [29]. Its severity can lead to meningitis, septicemia, and abortion; additionally, it has an almost 20–30% fatality rate, has a long incubation period, and affects pre- dominately immune-suppressed people [25]. L. monocytogenes also is known as a hardy organism, which can survive in the most unfavorable conditions like refrig- eration temperatures, food preservatives (i.e., high salt concentration), wide pH range, and conditions with little or no oxygen [6, 25]. According to CDC, pregnant women are ten times more likely to be infected by listeriosis than people in general, whereas others report that they are 20 times more likely to contract the illness [7, 30], and about one in seven, i.e. 14%, of the cases of Listeria infection happens dur- ing pregnancy [28].
A pregnant woman will experience mild flu-like symptoms, fever, chills, head- ache, backache, occasionally upset stomach, abdominal pain, and diarrhea.
Listeriosis can lead to gastrointestinal problems, with symptoms appearing within a few hours to 2–3 days, and disease appearing 2–6 weeks after digestion. The illness can grow even more severe and can lead to death [5]. It may even lead to miscar- riage, stillbirth, premature delivery, or serious infection of newborn, neonatal sep- sis, chorioamnionitis, and meningitis [25, 30].
Incidents of Listeriosis were reported when hot dogs, luncheon meats, cold cuts, fermented or dry sausage, and other deli-style meat and poultry products were improperly reheated and consumed. Food prepared in retail environments like cut melon and hummus were also known to be responsible for the illness. Unpasteurized (raw) milk and soft cheeses made with unpasteurized (raw) milk, smoked seafood, salads made in stores like ham salad, chicken salad, or seafood salads, and raw veg- etables are other risk-associated foods. Mexican-style soft cheese, queso fresco, made from unpasteurized milk, pasteurized milk products, hot dogs, and deli meats have all been associated with listeriosis outbreaks in the United States; likewise, there were outbreak cases associated with raw-milk soft cheese (Brie), pork tongue, and rillettes (pork paté) in France and Denmark [31]. The Food Safety Inspection Service (FSIS) recommends people at risk of listeriosis to reheat hot dogs and deli meats until steaming before consumption to kill any Listeria monocytogenes that
can be present. A recent survey with pregnant women indicated that surveyors reheat those foods to preserve quality and not because of food safety concerns [29].
Toxoplasmosis
Toxoplasmosis is an infection caused by the parasite Toxoplasma gondii, which can infect cats if they eat raw meat or rodents, and it remains in the cat’s feces for 2 weeks. The general mode of infection in humans is by consuming undercooked, infected meat, or by handling soil or cat feces containing the parasite [32, 33].
Toxoplasma gondii infects many people at some point of their lives, but causes little or no harm, and creates immunity against it for the future. However, almost 85% of pregnant women in the United States are susceptible to toxoplasmosis infec- tion because of their weakened immune system, leading to the fetus acquiring the infection too, which can cause spontaneous abortion or severe problems such as microcephaly, hydrocephalus, seizures, mental retardation, and chorioretinitis [32].
General symptoms of this infection are flu-like, which usually appear 10–13 days after eating, and can last months [5]. Infection can be avoided if meat is cooked until the pink color vanishes and juice runs clear, by wearing gloves while gardening, washing hands carefully after handling raw meat, fruits, vegetables, and soil, wash- ing all fruits and vegetables before consumption, and not coming in contact with cat feces or raw-meat cat food [32, 33].
Other Pathogens
For other pathogens that are responsible for food-borne illnesses, the symptoms and foods associated with the pathogen are as follows [5].
Salmonellosis caused by Salmonella typhi is itself not a major risk to pregnant women, but it may pass to the fetus, resulting in abortion, stillbirth, or premature labor. It is estimated that around 1.2 million cases of Salmonellosis occur each year in the United States [6], resulting in approximately 15,000 hospitalizations and 400 deaths [34]. Symptoms of Salmonellosis are stomach pain, diarrhea (can be bloody), nausea, chills, fever, and/or headache, and usually appear 6–72 h after eating, poten- tially lasting up to 4–7 days. Salmonellosis especially affects immunosuppressed people like pregnant women, and can lead to serious complications that can result in death. Foods associated with this illness are: raw or undercooked eggs, poultry and meat, unpasteurized (raw) milk or juice, cheese, seafood, and fresh fruits/
vegetables.
Campylobacteriosis is caused by Campylobacter jejuni and is responsible for 2.4 million human infections annually, killing approximately 100 people yearly, with the majority of the affected group being infants, elderly, or immunosuppressed indi- viduals [34]. The major sources for this infection are the consumption of untreated or contaminated water, unpasteurized “raw” milk, and raw or undercooked meat,
poultry, or shellfish. General symptoms that can be seen when encountered with this illness are fever, headache, and muscle pain, followed by diarrhea (sometimes bloody), abdominal pain, and nausea. Symptoms generally appear 2–5 days after eating and may last up to 10 days. It can also spread to the bloodstream, potentially causing a life-threatening infection.
Clostridium perfringens are bacteria that produce toxins harmful to humans, and are found everywhere in the environment. Food poisoning from Clostridium per- fringens is mainly associated with undercooked meats and food left at room tem- peratures for long periods of time. Food that is categorized as high-risk food will require time-temperature control for prevention of microbial growth and toxin pro- duction. Major sources of food that can cause this illness are meats, meat products, poultry, poultry products, and gravy. Consumption of contaminated food will result in the onset of watery diarrhea and abdominal cramps within about 16 h and illness that begins and lasts for 12–24 h. Complications and/or death are rare.
Cryptosporidium is generally found in soil, food, and water, especially that is used for recreational purposes (i.e., swimming pool or lake). Infection occurs when uncooked or contaminated food or water is consumed or a contaminated object is placed in the mouth.
Escherichia coli O157:H7 is one of several strains of E. coli that can cause human illness, potentially causing severe diarrhea (often bloody), abdominal cramps, and vomiting, with little or no fever. Symptoms can begin usually 1–9 days after contaminated food is eaten, and may last up to 9 days. Hemolytic-uremic syn- drome (HUS) can develop and cause acute kidney failure, leading to permanent kidney damage or even death in the very young. Foods associated with this infection are undercooked beef, especially hamburger, unpasteurized milk and juices, such as
“fresh” apple cider, contaminated raw fruits and vegetables, and water. The infec- tion can also be transmitted from person to person.
Norovirus causes nausea, vomiting, and stomach pain, where diarrhea is more common in adults and vomiting more common in children. Foods associated with this infection are shellfish, fecal-contaminated foods or water, and ready-to-eat foods that have been touched by infected food workers (e.g., salads, sandwiches, ice, cookies, and fruits).
Vibrio vulnificus-contaminated food causes diarrhea, stomach pain, and vomiting and can result in blood infection. It may also result in death for people with weak immune systems, such as pregnant women. Foods associated with this infection are undercooked or raw seafood (fish or shellfish).
Importance of Food Safety Education
Food safety education is important for all consumers, but essential for pregnant women [4]. Fortunately, pregnancy is a life-phase when women tend to be more receptive to health-, food safety-, and quality-of-life-related information, and are
often more motivated to change unhealthy habits [3]. However, research has shown that many women are not aware of the potential risks associated with listeriosis and toxoplasmosis exposure to the fetus during pregnancy. Research also points to a lack of education on safe food handling, and safe eating practices from healthcare practitioners [7, 8, 30]. A study conducted in British Columbia showed that about 88% of healthcare providers knew about listeriosis but only 35% counseled women about pregnancy risks [41]. Pregnant women do not consult midwives, registered nurses, registered dietitians, and prenatal educators, who are highly valued as the best sources of food safety information among at-risk patients [30, 35, 41], unless there is a reason to be concerned about food-related illnesses.
Physicians play a very important role in the circle of care [33, 36]. A study from Canada indicated that 92.3% of women met with a physician at least once during their pregnancies [36]. Healthcare professionals should take advantage of the fact that pregnancy can be one of the most important life events for women that prompts them to be nutritionally aware and open to nutrition-related information [37]. Food habits clearly have a major impact on food choices, and this makes it difficult under ordinary circumstances to alter a woman’s diet. However, health professionals have an opportunity to play a more influential role in affect- ing the dietary choices of pregnant women than information from any other sources [38].
Proper nutrition education is vital for successful and positive pregnancy out- comes. Nevertheless, pregnant women rely on midwives as a source of information regarding this subject matter [39], which put midwives in an influential role to deliver food safety education to pregnant women.[40] Other sources of information such as prenatal books, magazines, and web pages may also be a mode to deliver potential food-safety risk information to pregnant women [29].
Conclusion
Pregnant women are at high risk for food-borne illnesses because of hormonal changes that compromise their immune system. Improper handling and consump- tion of high-risk foods such as unpasteurized milk and dairy products, juices, raw sprouts, raw eggs, and raw meat/poultry/fish/seafood may lead to serious health hazards such as miscarriage, spontaneous abortion, meningitis, premature delivery, and neurological effects. Food-safety risk communication and consumer education to promote safer handling of food would manage the risk of potential food-safety hazards during pregnancy. Studies show that women tend to be motivated to make health-related behavior changes during pregnancy, which may make them receptive candidates for education of food safety. Healthcare professionals should take advan- tage of client receptivity to health information during prenatal visits to educate them on food-safety considerations in order to optimize the likelihood of a successful pregnancy outcome.
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