Among the six bacteria targeted by the above-mentioned detection method, enterohaemorrhagic Escherichia coli O157  is the most worrying. Indeed this causes haemorrhagic colitis but also releases toxins which destroy the inner layer of blood vessels. These are serious illnesses which can lead to nerve and/or kidney failure. 
It is clear then, the complications of a contamination are rare but can have dramatic consequences, especially on the health of individuals at risk (babies, elderly people, pregnant women and immunodeficient  people).

Escherichia coli, a sentinel bacteria for the environment

The icing on the cake with regards to seafood, molluscs and crustaceans can also contain concentrations of  marine biotoxins from microalgae known as dinoflagellates. "It must therefore be remembered that when we speak about symptoms following the ingestion of seafood, this can be due either to biotoxins or microorganisms", continues Georges Daube. To minimize the risks linked to biotoxins, the authorities are monitoring the quality of seawater and the quantity of dinoflagellates. "It is particularly due to these particular microalgae that, each summer,  oyster harvesting is forbidden in the Arcachon basin, for example", explains the scientist. Controlling the levels of microorganisms is currently done in the presence of an excessively high concentration of a bacteria, Escherichia coli (not to be confused with its pathogenic enterohaemorrhagic variant O157 mentioned above!), naturally present in the intestinal flora of humans and animals.  An excessive quantity of these bacteria reflects fecal contamination of water and an increased risk of finding some of the above-mentioned pathogens in molluscs.

"I can't recall there ever have been a large-scale epidemic in Belgium, but in France, where there are more seafood farms and a greater consumption of seafood, the germs mentioned in our article have already caused several epidemics", indicates Georges Daube.

There is no need for panic or a ban on oysters, lobsters or other kinds of seafood. It is simply a matter of noting that it is better to choose the option of products that are checked in-keeping with the law applied in the European Community.

Since 2009, the public health ministry has taken charge of the microbiology of foodstuffs. Georges Daube's laboratory has been specializing in microbial ecosystems, that is to say, all the microorganisms present in a biological sample. "This still covers food but also, more broadly speaking, water, the digestive apparatus, the environment etc. We use more efficient methods of high-throughput sequencing, thanks to which we can identify all the bacteria and viruses in a given biological sample", explains the researcher.