Scientists have renewed calls for a listeriosis reporting network across the EU, pointing to the relatively high rates of the deadly disease throughout the bloc.
The network would track and trace incidences of the disease back to the source. Such information would help regulators and industry focus their efforts on reducing listeriosis, they say.
The repeated call for such a reporting network puts processors under the gun to prevent the deadly 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.
Rates of listeriosis may be increasing or remaining stable at relatively high levels in the EU, says an editorial published in Eurosurvelliance. The authors, scientists at the Institut de veille sanitaire, in Saint-Maurice, France and the University of Minnesota, call for a specialised reporting network for Listeria, the bacteria that causes the disease.
"Where rates of listeriosis are declining, such as in France, this appears to be the result of extensive surveillance efforts to define the scope of the problem, followed by active collaboration between public health officials, food regulatory officials and food producers to reduce the levels of contamination in the food supply," they stated.
They noted that European food safety standards will help establish consistent approaches to the control of Listeria in ready-to-eat foods.
However, implementation of these standards will still require extensive collaborations at the national level, they say. They noted that an aging demographics throughout Europe makes a larger percentage of the population more vulnerable to the disease, as shown by the statistics.
"Reliable surveillance data on listeriosis are a foundation upon which effective collaborations are built," they say. "Strengthening surveillance in individual countries by harmonising microbiological methods and providing epidemiologic tools for investigations will be a key step in reducing the public health burden of listeriosis, even as the population at risk grows. Thus, the need for a European surveillance network for Listeria has never been greater."
In 2002, reported incidence of listeriosis in Europe ranged from 0 to 7.5 cases per million inhabitants, the report stated.
The highest rates were reported from countries that had statutory notification of Listeria infections and surveillance through a national reference laboratory, the scientists found.
Incidents of listeriosis rise in countries where a notification system has been set up for the disease, indicating past statistics do not indicate the full extent of the problem.
The relationship between public health investment in surveillance and increased yield in reported cases has been demonstrated by statistics in the Netherlands.
Although listeriosis is not a notifiable disease in the Netherlands, implementation of more active surveillance in January 2005 has resulted in a 43 per cent increase in the reported incidence of listeriosis.
In France, the incidence of listeriosis has declined from 4.5 cases per million inhabitants in 1999-2000, to 3.5 cases per million inhabitants during the period from 2001-2003s.
In Finland, the number of reported cases varied markedly by year from 1995-2004, but there was no clear trend. The mean annual incidence was seven cases per million inhabitants, they reported.
In Germany, the incidence rate increased from 2.6 cases per million inhabitants in 2001 to 6.2 cases per million inhabitants in 2005. Most of the increase occurred among people over 60 years of age .
A similar increase in listeriosis among people over 60 years of age occurred in England and Wales from 2001-2004.
In France and Finland, special techniques resulted in the detection of several case clusters and common-source foodborne outbreaks, they say.
In Switzerland the incidence of listeriosis has been stable but relatively high. In the UK incidence rates havebeen increasing.
"There has been considerable institutional support for developing a European Listeria network, and in response to planning efforts, Listeria surveillance has improved in several countries," the scientists say. "However, the network has yet to be realised."
A similar study published last year found changes in the way food is produced, distributed and stored have created the potential for diffuse and widespread outbreaks involving many countries.
In 2004 the 25 EU member countries reported a total of 1,267 cases of listeriosis. The reported incidence in the EU in 2004 was 0.3 cases per 100,000 population which is similar to 2003.
Listeria monocytogenes causes listeriosis in humans. A wide range of contaminated foods is associated with its transmission, including meat, dairy, fish, shellfish and vegetable products. Listeria is killed by pasteurisation and cooking.
However, in certain ready-to-eat foods such as hot dogs and deli meats, contamination may occur after cooking but before packaging.
In humans, Listeria monocytogenes may cause severe pathologies, such as meningitis, septicaemia and encephalitis, as well as abortions. Groups at greatest risk include pregnant women, neonates, immunocompromised patients and the elderly.