Investigation into pregnancy-linked Listeria case finds more sufferers


Investigations into a case of pregnancy-related listeriosis revealed a wider outbreak in Italy, according to a study.

In January 2020, a 28-year-old pregnant woman, living in a town near Rome, was admitted to a hospital in Rome.

A caesarean section was performed and a baby girl was born. The baby suffered from respiratory distress and was diagnosed with hyaline membrane disease. Blood culture samples, taken a few hours after birth, showed the growth of Listeria monocytogenes. She was transferred to the neonatal intensive care unit for invasive ventilation for 24 hours. The baby was released a month later in good clinical condition.

After notification of the case of listeriosis, a survey of the local health authority gave an epidemiological questionnaire to the mother to assess possible dietary exposures during the 30 days preceding the onset of the disease.

Based on the responses, the health agency’s attention focused on fresh horse meat purchased from the local butcher and charcuterie at the deli counter purchased from one of two supermarkets.

Additional investigations found three more cases from May 2019 to May 2020. The first case involved a patient admitted to the emergency room. The second patient was hospitalized in April 2020. The third case occurred in May 2020. A patient confirmed going to the same supermarket as the mother of the neonatal listeriosis case, the study says, published in the Pathogens review.

Contaminated equipment
The outbreak was linked to the consumption of ready-to-eat sliced ​​products sold in supermarkets.

Samples of a large Italian sausage, called mortadella, from one of the supermarkets inspected tested positive for Listeria monocytogenes. Samples from two meat slicers in the store tested positive for Listeria monocytogenes, as well as from the cold food counter where deli meats were available to the public.

An investigation suggested that the source of contamination had been active for a long time before and after the official inspection by the local health authority. After sanitizing the premises, the self-checking sample and by the health unit proved negative, the catering counter was reopened.

Contaminated food products transmitted the infection from mother to baby. The mother’s gastrointestinal symptoms were likely mistaken for labor contractions, according to the study.

The Listeria monocytogenes strain causing the incident is not common in the country and appears to be limited to central Italy, mainly the Lazio region.

The researchers said ongoing education on dietary precautions for pregnant women is needed to reduce the occurrence of listeriosis.

“This study highlights the importance of constant surveillance of foodborne illnesses carried out by health authorities in collaboration with clinicians and laboratories, from notification to investigation. The main objective is to identify and stop the source of contamination as soon as possible, in order to avoid the extension of a foodborne epidemic,” the researchers wrote.

Foodborne disease investigations in two regions
At the same time, another study, in the Toxins magazinedetails three years of foodborne infection investigations involving the Food Microbiology Unit of the Istituto Zooprofilattico Sperimentale del Lazio e della Toscana (IZSLT) in Italy.

There were 13 surveys in 2020 compared to 28 and 29 in 2018 and 2019. The researchers said the COVID-19 pandemic was likely to blame for the decline.

Data from 70 foodborne surveys were analyzed. A total of 19 of 340 food samples were positive for a bacterial pathogen, toxins or both. Of the positives, more than half were for meat products. The samples studied were collected by the authorities, mainly in the regions of Lazio and Tuscany. The main pathogen detected was Listeria monocytogenes. He was found six times.

Only 17 of the 70 investigations occurred following an official report of foodborne illness by the healthcare system with the patient having a clinical diagnosis. Of the remaining cases, 29 started with a direct report from the consumer after the onset of symptoms and 24 followed a report from authorities without any information about the patient’s condition.

“Despite the severe impact of foodborne illness on human health and the economy, investigation of many foodborne outbreaks fails to identify the source of infection. This indicates the need for competent authorities to continue to develop and implement a more integrated health network,” the researchers said.

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