Cancer Patients Warned Over Smoked Fish

The findings are published in the journal of Emerging Infectious Diseases, according to the HPA.

Listeriosis is a rare but serious foodborne illness caused by the bacterium, Listeria monocytogenes. Some groups of people can be more seriously affected by this type of food poisoning than others. Pregnant women and their unborn or newborn babies are at most risk, as well as the elderly and those with conditions that affect their immune system.

The incidence of listeria in England and Wales has increased in recent years, with 2.1 cases per million of the population between 1990 and 2000 to 3.6 million cases per million in the period 2001 and 2009. This increase also revealed greater numbers of cases in people over 60 years of age. Similar increases have also been seen in other countries in Europe.

The team at the HPA reviewed 1,413 people who had listeria between 1999 and 2009 in England. Pregnant women and their unborn or new born children were not included in the study. Of these people, 936 – over two-thirds or 66 per cent – had one or more concurrent condition.

The research revealed that among those with concurrent conditions, people aged 60 years or over had a higher rate of listeria at 16.8 per million as compared to younger people whose rate was 4.6 per million.

Overall, the rate of listeria was 4.9 times higher for cancer patients than for patients with other concurrent conditions. Within the cancers the highest rate was among those with cancers of the blood – which was 17.6 times higher than for other conditions. Cancer was also the most common concurrent condition among cases of listeria, with a malignancy reported for a third of cases. Blood-borne cancers accounted for 41 per cent of the reported cancers.

In addition to cancer, diseases of the liver, kidney and connective tissue (e.g. Lupus) as well as alcoholism, diabetes, high blood pressure and inflammation of the intestines (e.g. Crohn's disease) were also found to increase the risk of developing listeria.

Dr Bob Adak, head of epidemiology services in the gastrointestinal diseases department at the HPA, said: "Our research has shown that those receiving cancer treatment or suffering from a variety of conditions, including diabetes, kidney or liver disease, should be offered appropriate health advice on how to avoid listeria. At present, this is given passively and mainly to pregnant women but clearly there are other groups of people who need to be advised on what they can do to protect their health.

"Listeria can cause serious illness or even death in those people who have serious underlying health conditions. Taking steps to avoid infection is a very important part of managing their health and these groups need to be made aware of how they should do this."

The current public health advice to vulnerable groups on preventing listeria is to avoid the following: pre-packed or delicatessen sliced meats; soft cheeses such as brie, camembert and chevre (goat's cheese); smoked fish; all kinds of paté including vegetable varieties; pre-prepared cooked and chilled meals; pre-prepared sandwiches and unpasteurised milk.