Listeriosis During Pregnancy Can Be Fatal for the Fetus

Listeriosis during pregnancy, when invasive, can be fatal for the fetus, with a rate of fetal loss or neonatal death of 29%, investigators reported in an article alerting clinicians to this condition.
The article was prompted when the Reproductive Infectious Diseases team at The University of British Columbia in Vancouver, British Columbia, Canada, “received many phone calls from concerned doctors and patients after the plant-based milk recall in early July,” Jeffrey Man Hay Wong, MD, told Medscape Medical News. “With such concerns, we updated our British Columbia guidelines for our patients but quickly realized that our recommendations would be useful across the country.”
The article was published online on August 26 in Canadian Medical Association Journal.
Five Key Points
Wong and colleagues provided the following five points and recommendations:
First, invasive listeriosis (bacteremia or meningitis) in pregnancy can have major fetal consequences, including fetal loss or neonatal death in 29% of cases. Affected patients can be asymptomatic or experience gastrointestinal symptoms, myalgias, fevers, acute respiratory distress syndrome, or sepsis.
Second, pregnant people should avoid foods at a high risk for Listeria monocytogenes contamination, including unpasteurized dairy products, luncheon meats, refrigerated meat spreads, and prepared salads. They also should stay aware of Health Canada recalls.
Third, it is not necessary to investigate or treat patients who may have ingested contaminated food but are asymptomatic. Listeriosis can present at 2-3 months after exposure because the incubation period can be as long as 70 days.
Fourth, for patients with mild gastroenteritis or flu-like symptoms who may have ingested contaminated food, obtaining blood cultures or starting a 2-week course of oral amoxicillin (500 mg, three times daily) could be considered.
Fifth, for patients with fever and possible exposure to L monocytogenes, blood cultures should be drawn immediately, and high-dose ampicillin should be initiated, along with electronic fetal heart rate monitoring.
“While choosing safer foods in pregnancy is recommended, it is most important to be aware of Health Canada food recalls and pay attention to symptoms if you’ve ingested these foods,” said Wong. “Working with the BC Centre for Disease Control, our teams are actively monitoring for cases of listeriosis in pregnancy here in British Columbia.
“Thankfully,” he said, “there haven’t been any confirmed cases in British Columbia related to the plant-based milk recall, though the bacteria’s incubation period can be up to 70 days in pregnancy.”
No Increase Suspected
Commenting on the article for Medscape Medical News, Khady Diouf, MD, director of global obstetrics and gynecology at Brigham and Women’s Hospital in Boston, said, “It summarizes the main management, which is based mostly on expert opinion.”
US clinicians also should be reminded about listeriosis in pregnancy, she noted, pointing to “helpful guidance” from the American College of Obstetrics and Gynecology.
Although the United States similarly experienced a recent listeriosis outbreak resulting from contaminated deli meats, both Wong and Diouf said that these outbreaks do not seem to signal an increase in listeriosis cases overall.
“Foodborne listeriosis seems to come in waves,” said Wong. “At a public health level, we certainly have better surveillance programs for Listeria infections. In 2023, Health Canada updated its Policy on L monocytogenes in ready-to-eat foods, which emphasizes the good manufacturing practices recommended for food processing environments to identify outbreaks earlier.”
“I think we get these recalls yearly, and this has been the case for as long as I can remember,” Diouf agreed.
No funding was declared, and the authors declared no relevant financial relationships.
Marilynn Larkin, MA, is an award-winning medical writer and editor whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, the Lancet (where she was a contributing editor), and Reuters Health.
 
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