cheeses

[Kar]

Danni
Here is what the Australian Food Standards website says (I've added the red emphasis):

How common is listeriosis?

Listeriosis is a rare disease. The reported incidence of the disease is much lower than for many other foodborne diseases, but the consequences of infection are severe. In Australia there are approximately 60 cases of listeriosis notified to health authorities each year. The majority of these are in elderly patients or people who have suppressed immune systems.

Most cases of human listeriosis are sporadic and the sources and route of infection are usually unknown, however, contaminated food is considered to be the major route of transmission. Incubation periods range from a few days up to three months.

A small number of infections (less than 10 per year) occur in pregnant women and their unborn child. However, the true incidence is unknown as such infections are often not investigated or diagnosed. Testing is not routinely conducted on miscarried foetuses.

How dangerous is listeriosis?

There is evidence to suggest that Listeria is a transitory resident of the intestinal tract in humans, with 2-10% of the general population being carriers of the organism without any apparent adverse health consequences. In susceptible populations the bacteria most often affects the bloodstream, the central nervous system or the pregnant uterus.

Manifestations of listeriosis include bacteraemia/septicaemia, meningitis, meningoencephalitis, encephalitis, miscarriage, stillbirth, premature birth, neonatal disease and prodromal illness in pregnant women. Listeriosis has a high mortality rate of up to 50% for maternal-foetal infections and around 20% for non-pregnancy related infections.

And here is what it says about food:

Information about Listeria and food

How does Listeria get into foods?

Australia has a well-deserved reputation for a safe food supply and food manufacturers and processors have implemented systems designed to prevent Listeria contamination. However, Listeria is widespread in the environment and ready-to-eat foods might become contaminated after processing or at some later stage between the processing plant and the consumer’s plate. Contamination might also occur through improper hygiene of food handlers, or by cross-contamination after contact with raw foods or contaminated surfaces.

Unlike most food poisoning bacteria, Listeria continues to grow slowly even at refrigeration temperatures. It will grow more rapidly at higher temperatures, so foods that have been kept for a long time and/or that have not been kept cold may represent a higher risk to susceptible people.

Listeria bacteria may be present in certain types of foods such as pre-prepared uncooked foods or pre-cooked foods that have been kept for some time.

What precautions should I take if I am ‘at risk’?

The foods most often associated with listeriosis are ready-to-eat foods that support the growth of Listeria; have a long refrigerated shelf life; and are consumed without further listericidal treatmentsi.e.don’t receive any further processing/cooking such as reheating to 74°C for 2 minutes.

Foods that are packaged (i.e. food fully encased in a wrap or container by the manufacturer and not intended to be unwrapped except by the final consumer) do not usually present the same risk as unpackaged food or food on open display at a delicatessen counter, smorgasbord, sandwich bar or salad bar, etc. This is because unpackaged foods are more likely to become contaminated by Listeria from other foods also on display. Also, it is not always known how long unpackaged foods have been on display.

For people at risk of acquiring listeriosis, it is advisable to eat freshly cooked or freshly prepared foods. Freshly cooked foods are safe because cooking destroys Listeria bacteria. Also, the opportunities for contamination by Listeria is minimised as there is only a very short time before the meal is consumed. Foods should be cooked to a minimum internal temperature of 74°C to destroy the Listeria bacteria.

Prepare foods such as fruit salads, green salads and vegetable dishes shortly before eating. Eat well washed, freshly prepared fruit and vegetables in preference to fruit and vegetable dishes that have been prepared in advance and stored chilled for long periods. Storing food in chillers does not prevent growth because Listeria will grow at refrigeration temperatures. Try to avoid stored food, as it is impossible to know by appearance, smell or taste whether food is contaminated.

Where possible, only prepare sufficient food for the meal, and avoid the accumulation ofleftovers. Ifthereareleftovers,theyshouldberefrigeratedprompt ly. WhileListeriacangrowslowlyatlowtemperatures(<5°C) , eating leftovers within a day provides limited opportunity for Listeria to grow.

Do not eat food if there is any doubt about its hygienic preparation or storage. Refer to the good food hygiene guide in the Listeria and food – advice for people at risk pamphlet and the detailed notes later in this document.

It then goes on to list HIGHER RISK FOODS.
For Cheeses its says: Soft, semi-soft and surface ripened cheeses (pre-packaged and delicatessen) e.g brie, camembert, ricotta, feta, blue.

The SAFER ALTERNATIVES for cheese are listed as:

• Hard cheese (cheddar) stored in the fridge.
  Processed cheese, cheese spreads, plain cream cheese, plain cottage cheese purchased packaged by the manufacturer and stored in the fridge

In other words its RUSSIAN ROULETTE. Most of the time it's going to be ok. But maybe some time it's not.

Ryn - my understanding is the risk and prevalence is MUCH lower in the UK than in Australia. I think I read that there were only 20 cases in pregnant women per year whereas there are about 10 per year in Australia. Only our population is wincy compared to yours - so our odds here in Oz are worse.