Projects / Programmes
Factors which influence on bacterial and viral infections in mussels
| Code |
Science |
Field |
Subfield |
| 4.04.05 |
Biotechnical sciences |
Veterinarian medicine |
Sanitary protection of animal origin food |
| Code |
Science |
Field |
| B230 |
Biomedical sciences |
Microbiology, bacteriology, virology, mycology |
| Code |
Science |
Field |
| 4.03 |
Agricultural and Veterinary Sciences |
Veterinary science |
food safety, mussels, sampling, classification, bacteria, viruses, risk assessment
Researchers (18)
Organisations (3)
Abstract
Consuming of raw or insufficiently cooked shellfish, harvested in waters contaminated by feces, may be reason for the occurrence of food-borne infections in humans. Shellfish are feeding by filtering of water and can accumulate also pathogenic bacteria, viruses or toxins. Therefore, the contamination of sea water is an important limiting factor in shellfish harvesting areas. The level of contamination can also be affected by the sea currents, seasons, rainy and dry periods, and many other physical and chemical factors. In Slovenia, there are three registered mussel harvesting areas; Seča, Strunjan and Debeli rtič, which are according to the law classified in the category B, so the mussels need to be purified prior to the sale. The purification increases the cost of production, which reduces the competitiveness of the Slovenian mussel producers on the market. Harvesting areas are classified according to the number of E. coli, which are used as an indicator, while the presence of the viruses has not yet been intensively studied. In our study we will identified all potential contaminants of seawater, which produce microbial contamination of mussel harvesting areas. We will analyze the data collected from different monitoring programs to assess the quantities of organic contaminants released during the different period of seasons. The sampling will be carried out in Seča , Strunjan and Debeli rtič and in a natural habitat of mussels near Piran. During the period of 13 lunar months, samples of mussels and water will be collected three times monthly and records of several physical and chemical measurements (the dynamics of sea currents, water temperature, pH, dissolved oxygen...) will be done. In collected samples of water the number of E. coli will be determined, while in samples of collected mussels E. coli and the presence of noroviruses and hepatitis A will be detected. The indicator microorganism (E. coli), among which also pathogenic strains may be present, will be determined for the presence of genes that allow pathogenic bacteria their anti-microbial resistance. For the determination of E. coli the prescribed methods in ISO standard and the validated methods of polymerase chain reaction (PCR) will be used. For the detection of the different viruses specific methods based on RT-PCR will be used. Results of microbiological and virological tests will be analyzed along with all environmental parameters included in the survey and statistically evaluated. With the implementation of the project we will get the detailed information about contamination of mussels with bacteria and viruses. Based on the data analysis we will propose changes of the classification of production harvesting areas and proposal for scope and method of sampling will be suggested. We will interpret the results of samples tested in our study. Data will be collected and analyzed together with the data of previous studies regarding contamination of mussels to produce a risk assessment analysis. We will determine the emergence of viruses in specific locations and identify the potential impact of the major discharges of fecal sewage in surrounding area. Based on the risk assessment analysis the competent authority will have more effective control of quality and safety of harvested seafood. This survey will assist food business operators - mussel producers to ensure the safety of food production, for which they are responsible.
Significance for science
With intensive one-year monitoring of the physical, chemical and microbiological parameters in Mediteranean mussels (Mytilus galloprovincialis) and sea water from the production areas, we obtained a broad view about the mariculture situation in Slovenia. These results were connected with special events at the sea, such as strong winds, heavy rainfall, sea currents and other sources of pollution. With molecular methods we determined the presence of norovirus strains. Regarding their genetic characterization it is possible to make an epidemiologic connection with outbreaks in humans, if they occur. In addition to the E. coli analysis in bivalve molluscs we gathered and evaluated information on the impact of other parameters measured at the same time. With planned collection of the samples, results were obtained of the individual locations of mussels harvesting areas. We tested antimicrobial resistance of the isolated E. coli strains and determined the presence of virulence factors. We got insight into a range of such strains in this marine ecosystem. The isolated strains were also sorted into groups of pathogenic or commensal bacteria. This data is helpful in marine ecology research and important in terms of food safety. By knowing the risk factors and their correlation with the incidence of viruses and bacteria in shellfish a report was produced on the assessment of food safety.
Significance for the country
All live bivalve molluscs, placed on the market for direct human consumption must comply with the microbiological criteria laid down in Regulation (EC) 2073/2015 and health standards for live bivalve molluscs, as defined in Chapter V of Section VII of Annex III of Regulation (EC) No. 853/2007 concerning the organoleptic characteristics and presence of marine biotoxins. Shellfish harvesting areas in Slovenia are classified as B cathegory, in comparison with the neighboring harvesting areas in Croatia and in Italy, in a lower category. Shellfish breeding takes place in highly variable conditions with a number of external influences. Through the analysis of the contamination of shellfish we wanted to determine whether certain Slovenian harvesting areas could be placed in class A, which could result in a better market position of the producers and reduce their production costs. Assessment of the sources of pollution in the coastal waters, which affects the quality of seawater in harvesting areas, is useful information and helps to determine the new locations for harvesting and possible expansion of the existing ones. Yearly production of mussels, cultivated in Seča, Strunjan and Debeli Rtič, increased to 500 tonnes in the last decade. The cost of production increases with the additional purification in the depuration centre. With the study we determined the level of microbiological contamination of harvested and wild mussels in the Slovenian coastal waters. In determining the contamination, we focused on E. coli, hepatitis A virus and norovirus; in addition, we have examined the samples of marine water from harvesting areas for the content of E. coli and enterococci and we determined the content of metals in the Mediterranean mussel and in sea water. By monitoring the quality of seawater in shellfish harvesting areas and the impact of environmental pollutants, we recorded the risk factors and made proposals to reduce such risks. By knowing the risk factors and their correlation with the incidence of viruses in shellfish we created a report with an emphasis on the food safety for all Slovenian harvesting areas. These findings can be used by the responsible institutions in Slovenia to carry out more effective control of the quality and safety of farmed seafood; they can also serve as guidance and assistance for the food business operators in ensuring the safety of produced food for which they are responsible. The research carried out in combination with risk assessments, in particular in the field of viral contamination of shellfish, may be used by consumers as a reference for the prevention of such infections. Data on the impact of environmental factors such as characteristics of the sea (depth, tides, sea currents) and weather events, which were monitored during the research, allow for an understanding of complex developments in the marine ecosystem. The results of periodic monitoring of contamination in some shellfish harvesting areas are useful for the planning of samplings for the purposes of official controls, as well as for the needs of internal control operators.
