It is now recognised that not all strains of Listeria monocytogenes cause disease. Pathogenicity (the ability of an organism to cause disease) for humans is generally confined to certain strains of L. monocytogenes. One particular strain causes 40% of foodborne outbreaks.
Current research is now focussing on understanding why certain strains of L. monocytogenes are more pathogenic than others. Research has revealed that certain genes are more commonly found in pathogenic strains of L. monocytogenes and are absent in less pathogenic strains. This may eventually allow the development of tests to further distinguish pathogenic and non-pathogenic strains. However, this is complicated since the severity of disease i.e. virulence, is linked to individual immunity and certain people are more likely to contract listeriosis than others.
Posted by Dr. Tim Sandle