With an EU scientific study recommending that the European Commission set up a system to track deadly listeria infections in the bloc, processors will be under the gun to prevent the bacteria from entering the food chain.
Outbreaks of listeriosis lead to the death of about 20 per cent to 30 per cent of those infected, one of the highest case fatality rates of all the foodborne diseases in the EU.
"Changes in the way food is produced, distributed and stored have created the potential for diffuse and widespread outbreaks involving many countries," the report's authors stated.
Listeriosis is a foodborne disease. The discovery of Listeria monocytogenes, mainly in raw and ready-to-eat meat, poultry, seafood and dairy products, has prompted numerous product recalls, whichhave led to large financial losses for the food industry and numerous health scares.
They noted that public health authorities did not always recognise the prominence of listeriosis in causing infection, particularly since it is a relatively rare disease compared with other commonfoodborne illnesses such as salmonellosis.
Most countries within the European Union have an annual incidence of listeriosis of between two to 10 reported cases per million population per year.
However, because of its high case fatality rate, listeriosis ranks among the most frequent causes of death due to foodborne illness. It ranks as the second leading cause of fatalities fromfoodborne diseases after salmonellosis in the US and France, and fourth in England and Wales.
Effective prevention and control measures exist and have worked to bring down the rate. Programmes in France have reduced the incident rate to about a third of what it used to be, and in the US byhalf. The reduction was attributed to increased regulatory activity, the implementation of Hazard Analysis and Critical Control Points (HACCP) programmes throughout the food industry, andspecific recommendations to high-risk groups.
However, several countries still have relatively high incidence, and many countries do not have a surveillance system that allows them to estimate incidence or evaluate incidence trends, thereport's authors stated.
"Moreover, its common source epidemic potential presents a real threat and persists even in countries with a decreasing or low incidence," they stated. "Changes in the wayfood is produced and distributed have further increased the potential for diffuse and widespread outbreaks involving many countries. Because these outbreaks can be dispersed with a limited number ofcases in each country, they are likely to go undetected if information from these countries is not pooled."
Improved surveillance, coordinated at a European level can identify and halt potentially large outbreaks, they recommend.
The study participants included 14 EU countries. They are Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, the Netherlands, Portugal, Spain, Sweden, and the UK, alongwith Norway, Iceland and Switzerland.
Surveillance systems for listeria infections were in operation in 16 out of the 17 countries. Portugal was the exception. The study found that 16 countries also had a national reference laboratoryto which outbreaks could be referred, with Ireland being the exception.
"The participants concluded that there was a clear added value to having a European surveillance network for listeria infections, particularly for outbreak detection and investigation, andthat a surveillance network based on the existing national surveillance systems was feasible," the authors stated.
The authors do not consider notification of foodborne illness and outbreaks to be the same thing as a surveillance system for listeriosis. Listeriosis was statutorily notifiable in 10 countries,while four countries had universal voluntary reporting.
Between 1991 and 2002, the study period, a total of 19 outbreaks of invasive listeriosis were reported in nine different countries, with a total of 526 outbreak related cases.
While the number of reported outbreaks increased gradually over time, from seven outbreaks detected in the period 1992-1996 to 11 in the period 1997-2001, the mean number of cases related to theseoutbreaks decreased from 57 to 11 over the same period.
"This suggests more efficient outbreak detection, investigation and control," the authors stated. In addition, four outbreaks of acute listeria gastroenteritis were reported. Twooccured in Italy, one in 1993 involving 18 cases and another in 1997 involving 1,566 cases. An outbreak in Denmark in 1996 led to three cases and an outbreak in Belgium in 2001 led to two cases ofacute gastroenteritis and one case of invasive listeriosis.
The food at the origin of the invasive listeriosis outbreaks was processed meat products (six outbreaks), cheese (five outbreaks), processed fish products (three outbreaks), butter (one outbreak)and undetermined (three outbreaks).
The incriminated products for at least six of these outbreaks were known to have been exported, creating the potential for the occurrence of outbreak related cases in other countries. Cases relatedto one outbreak in one country were diagnosed in a neighbouring country.
The outbreaks of gastroenteritis were linked to the consumption of contaminated rice salad and corn salad. The Belgian outbreak of gastroenteritis and invasive listeriosis was linked to acontaminated ice cream cake. The origin of one outbreak of gastroenteritis remained undetermined.