An investigation protocol to manage a foodborne outbreak in a disaster event

Background

During disaster events, the displaced populations living in tent camps are at high risk from foodborne illness outbreaks (FBO) as in these circumstances it is difficult to follow proper hygienic procedures during food handling and storage. When an outbreak occurs, an epidemiological investigation able to identify the source(s) of the exposure is essential to rapidly establish control measures to prevent continuing episodes of illness. This work aimed to evaluate the effectiveness and the applicability under simulated field conditions of an investigation protocol to be used during a FBO. Moreover, the application of the software ‘TOSSINFO' for data analysis was evaluated.

Methods

In May 2018, a FBO associated with the consumption of a tuna affecting 46 out of 75 people present in a tent camp in southern Italy was simulated. During the simulation, two teams of doctors and veterinarians participated in the investigation. The investigation protocol involved three steps: environmental inspection, epidemiological investigation, and data analysis through TOSSINFO. This software allows calculating different epidemiological indicators, several measures of association, and the visualization of the progression of the outbreak through epidemic curves.

Results

At the end of the exercise, both teams were able to trace the source of the infection. After data collection and data analysis, the groups demonstrated a strong association between illness people and tuna consumption. Furthermore, the teams achieved similar

Results

RR (7.50 vs 7.01), OR (27 vs 28), and Chi-square (12.1 vs 10.1).

Conclusions

The results demonstrated the validity of the procedure and the simple execution of the software analysis. These guidelines represent an opportunity for the implementation of foodborne disease management strategies and could be used throughout the community, leading to an improvement of the Public Health surveillance system.

Key messages

These guidelines allow for effective management of a food toxinfection episode. The original software TOSSINFO used in this procedure enables quick and easy identification of infected food.

Droplet Digital PCR (ddPCR) Analysis for the Detection and Quantification of Cow DNA in Buffalo Mozzarella Cheese

Simple Summary

Buffalo mozzarella cheese, sold as a Protected Designation of Origin (PDO) product, is made exclusively from Mediterranean buffalo (Bubalus bubalis) milk. To maximize their profits and overcome seasonal shortages of buffalo milk, some producers have started to produce “PDO” buffalo mozzarella cheese by adulterating buffalo milk with milk from different species. such as bovine, thus defrauding consumers. This practice has led the Italian government to reinforce controls on food mislabeling and fraud through traceability mechanisms. The aim of this work is the development of a molecular assay—droplet digital Polymerase Chain Reaction technique (ddPCR)—able to detect the DNA of cow and/or buffalo milk in PDO buffalo mozzarella cheese, thus revealing fraud. The results have highlighted that, thanks to its high precision and sensitivity, the ddPCR could represent an efficacious means of supporting the official controls aimed at combating the adulteration of buffalo mozzarella cheese with bovine milk.

Abstract

Buffalo mozzarella cheese is one of the most appreciated traditional Italian products and it is certified as a Protected Designation of Origin (PDO) product under the European Commission Regulation No. 1151/2012. It is obtained exclusively from buffalo milk. If made from cow milk, or a mixture of buffalo and cow milk, buffalo mozzarella cheese does not qualify as a PDO product. In order to maximize their profits, some producers market buffalo mozzarella that also contains cow milk as a PDO product, thus defrauding consumers. New methods for revealing this fraud are therefore needed. One such method is the droplet digital Polymerase Chain Reaction (ddPCR). Thanks to its high precision and sensitivity, the ddPCR could prove an efficacious means for detecting the presence of cow milk in buffalo mozzarella cheese that is marketed as a PDO product. ddPCR has proved able to detect the DNA of cow and/or buffalo milk in 33 buffalo mozzarella cheeses labelled as PDO products, and experimental evidence could support its application in routine analyses.

The microbiota of water buffalo milk during mastitis

The aim of this study was to define the microbiota of water buffalo milk during sub-clinical and clinical mastitis, as compared to healthy status, by using high-throughput sequencing of the 16S rRNA gene. A total of 137 quarter samples were included in the experimental design: 27 samples derived from healthy, culture negative quarters, with a Somatic Cell Count (SCC) of less than 200,000 cells/ml; 27 samples from quarters with clinical mastitis; 83 samples were collected from quarters with subclinical mastitis, with a SCC number greater of 200,000 cells/ml and/or culture positive for udder pathogens, without clinical signs of mastitis. Bacterial DNA was purified and the 16S rRNA genes were individually amplified and sequenced. Significant differences were found in milk samples from healthy quarters and those with sub-clinical and clinical mastitis. The microbiota diversity of milk from healthy quarters was richer as compared to samples with sub-clinical mastitis, whose microbiota diversity was in turn richer as compared to those from clinical mastitis. The core microbiota of water buffalo milk, defined as the asset of microorganisms shared by all healthy milk samples, includes 15 genera, namely Micrococcus, Propionibacterium, 5-7N15, Solibacillus, Staphylococcus, Aerococcus, Facklamia, Trichococcus, Turicibacter, 02d06, SMB53, Clostridium, Acinetobacter, Psychrobacter and Pseudomonas. Only two genera (Acinetobacter and Pseudomonas) were present in all the samples from sub-clinical mastitis, and no genus was shared across all in clinical mastitis milk samples. The presence of mastitis was found to be related to the change in the relative abundance of genera, such as Psychrobacter, whose relative abundance decreased from 16.26% in the milk samples from healthy quarters to 3.2% in clinical mastitis. Other genera, such as SMB53 and Solibacillus, were decreased as well. Discriminant analysis presents the evidence that the microbial community of healthy and clinical mastitis could be discriminated on the background of their microbiota profiles.