Official NHS medical advice on the deadly listeria outbreak has warned that the disease can last in the body for up to 70 days before symptoms appear.
Pregnant women, the elderly and those with exiting conditions such as diabetes are particularly vulnerable to infection.
It has emerged that guidance from Public Health England has been issued to help doctors spot and treat listeria.
An outbreak of the disease prompted a massive recall of frozen food from supermarket shelves.
The Food Standards Agency (FSA) issued a product recall list of 49 items being sold in Tesco, Lidl, Aldi, Waitrose, Iceland and others.
The list of items recalled by Greenyard Frozen UK Ltd, which produced the food, covers a wide range of frozen products.
What is Listeria?
Listeriosis is a rare but serious foodborne illness caused by the bacterium Listeria monocytogenes that can be more serious for those individuals who have weakened immune systems, and also the elderly, pregnant women and infants.
What are the symptoms of infection?
Infection is rare in healthy individuals who will often display no symptoms, but may experience mild diarrhoea and abdominal cramps.
Further symptoms include fever, body ache, headache and febrile gastroenteritis.
Certain groups of people are more at risk of infection, including pregnant women and those over 60-years-old.
This also includes individuals with pre-existing conditions like cancer, HIV, solid or bone marrow transplantation, diabetes, iron overload, alcoholism and liver or kidney disease.
People taking steroids, chemotherapy or other immunosuppressive treatments are also more at risk.
How long can Listeria last in the body?
According to Public Health England, the incubation period of the disease ranges from 24 hours to 70 days.
While the majority of cases can be diagnosed in the first week after infection, some may take longer to detect.
Has anyone died from the disease?
A European Centre for Disease Prevention and Control (ECDPC) report revealed that five EU countries have been investigating an outbreak of invasive Listeria monocytogenes (L. monocytogenes) infections since 2015.
The report reveals that 11 people in the UK have been struck down, with six confirmed cases so far this year.
In 2017 two people's deaths were linked with the outbreak.
According to the ECDPC the majority of listeria monocytogenes was found in products from the 2017 season products.
It was found in sweetcorn most regularly, but also frozen mixed vegetables including sweetcorn, frozen spinach, and frozen greenbeans.
How is an infection treated?
In cases of invasive infection patients should be treated with intravenous antibiotics in line with the local hospital's antimicrobial policy.
First line antibiotics include amoxicillin, with or without gentamicin, depending on the patient's condition.
Non-pregnant cases with penicillin hypersensitivity, cotrimoxazole (trimethroprim / sulfamethoxazole) is an option.
Pregnant cases with penicillin hypersensitivity can be treated with vancomycin or meropenem (use with caution).
Public Health England labelled chloramphenicol as "not reliable" and associated with treatment failures.
Questions and answers on listeriosis from Public Health England
Why has this product been recalled?
Consuming food contaminated with Listeria bacteria can cause an infection called listeriosis, although this is rare with around 180 cases occurring each year in England and Wales. In most people, listeriosis comprises mild symptoms but in certain at risk groups infection can be more severe. These food products have therefore been recalled as a precautionary measure to prevent possible illness.
What are the symptoms of listeriosis?
The majority of healthy people will be unaffected but some people may develop symptoms of gastroenteritis such as abdominal cramps, diarrhoea and/or mild flu-like symptoms including a high temperature. These symptoms usually pass within three days without the need for treatment.
More rarely and usually in at risk individuals infection may spread to the blood or central nervous system leading to bacteraemia and/or meningitis and more severe symptoms.
Who is at risk?
Otherwise healthy individuals may develop symptoms of gastroenteritis but this normally gets better by itself without medical intervention and usually there is no progression to more severe disease.
Certain groups are more vulnerable and include:
• people over 65 years of age
• pregnant women and their unborn babies
• babies less than one month old
• people with a weakened immune system, such as those with HIV/AIDS, cancer, diabetes, kidney or liver disease
• People on immunosuppressant therapies, such as steroids, chemotherapy and other types of immunodulanting agents such as monoclonal antibody or anti TNF therapies
What should I do if I have consumed some of the recalled food product?
Fit and healthy individuals need do nothing further. If you have mild diarrhoeal symptoms these should clear up and normally do not require medical treatment. If you develop a temperature and/or flu- like symptoms you should seek medical advice.
Persons with a weakened immune system (see at risk groups Q3) who have no symptoms need do nothing further. The incubation period of listeriosis can be up to 70 days. If you develop a symptoms of gastroenteritis and a temperature or flu- like symptoms during this period you should seek medical advice immediately.
How is the disease detected in pregnant women?
Public Health England produced a flow chart for healthcare professionals to check if pregnant patient may have been exposed to listeria.
First they must see if the patient has symptoms like muscle, abdominal or back pain, nausea, vomiting of diarrhoea.
If they do the must check if the woman has a febrile temperature of more than 38C.
If yes, blood and placental tissue tests should be done and treatment for listeriosis started.
What should I do if I have bought recalled products?
In a statement the FSA said:" If you have bought any of the below products do not eat them. Instead, return the product to the store from where it was bought for a full refund.
"The products listed below might be contaminated with Listeria monocytogenes.
"Symptoms caused by this organism can be similar to flu and include high temperature, muscle ache or pain, chills, feeling or being sick and diarrhoea.
"Some people are more vulnerable to listeria infections, including those over 65 years of age, pregnant women and their unborn babies, babies less than one month old and people with weakened immune systems."
Full list of all the recalled products:
Pinguin Frozen Sweetcorn
- Pack size - All
- Batch code - All
- Best before - All codes to July 2020 inclusive
Pinguin Supersweet Sweetcorn
- Pack size - All
- Batch code - All
- Best before - All codes to July 2020 inclusive
Tesco frozen Mixed Vegetables and Peppers
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Tesco Broccoli Frozen Sweetcorn Peas and Spinach Steamer
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Pinguin frozen Golden Rice and Vegetables
- Pack size - All
- Batch code - All
- Best before - All codes to July 2020 inclusive
Tesco Growers Harvest Sweetcorn
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Tesco Frozen Growers Harvest Carrot Peas and Sweetcorn Steamer
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Tesco Frozen Growers Harvest Mixed Vegetables
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Tesco Frozen Broccoli, Carrot and Sweetcorn Steamer
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Tesco Frozen Every Day Value Sweetcorn
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
One Stop Frozen Sweetcorn
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Aldi Four Seasons Frozen Carrots, Peas & Supersweet Sweetcorn Steamers
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Ross Mixed Country Vegetables
- Pack size 1kg
- Batch code All
- Best before All codes to July 2020 inclusive
Aldi Four Seasons Frozen Carrots, Broccoli & Supersweet Sweetcorn Steamers
- Pack size -All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Aldi Frozen Four Seasons Mixed Vegetables
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Aldi Four Seasons Supersweet Sweetcorn
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Independent Mix Vegetables
- Pack size - All
- Batch code - All
- Best before - All codes to July 2019 inclusive
Waitrose Essential Supersweet Sweetcorn
- Pack size - E1kg
- Batch code - All
- Best before - Oct 2019, Nov 2019, Aug 2019
Waitrose Essential Vegetable Mix
- Pack size - E1kg
- Batch code - All
- Best before - All codes to Dec 2019 inclusive
Waitrose Fine Cut Vegetable Steamer
- Pack size - E640g (4x160ge)
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Waitrose Love Life Vegetable Medley Steamers
- Pack size - E640g (4x160ge)
- Batch code - P6163 P7021 P7080
- Best before - May 2018, Jul 2018, Sep 2018
by Sainsbury’s Mixed Special Vegetables
- Pack size - 1kg
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
by Sainsbury’s Mixed Vegetables
- Pack size - 1 kg
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Growers Pride Supersweet Sweetcorn
- Pack size - 750g
- Batch code - All
- Best before - All codes to July 2020 inclusive
by Sainsbury’s White Rice, Broccoli, Supersweet Sweetcorn & Peas Microwaveable steam bags
- Pack size - 540g (4x135g)
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
basics Mixed Vegetables
- Pack size - 1kg
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
by Sainsbury’s Carrots, Broccoli & Sweetcorn Microwaveable steam bags
- Pack size -540g (4x135g)
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Lidl Frozen Green Grocer’s Supersweet Corn
- Pack size -1kg
- Batch code -All
- Best before - All codes to Jan 2020 inclusive
Pinguin Mixed Vegetable
- Pack size - All
- Batch code - All
- Best before - All codes to July 2020 inclusive
Lidl Frozen Freshona Vegetable Mix
- Pack size - 1kg
- Batch code - All
- Best before - All codes to July 2020 inclusive
Lidl Green Grocer’s Mixed Vegetables
- Pack size - 1kg
- Batch code - All
- Best before - All codes to July 2020 inclusive
Lidl Green Grocer’s Baby Carrots, Peas, Green Beans & Sweetcorn Steamers
- Pack size - 640g
- Batch code - All
- Best before - All date codes
Lidl Green Grocer’s Fragrant Golden Rice Steamers
- Pack size - 400g
- Batch code - All
- Best before - All codes to July 2020 inclusive
Iceland Frozen Mixed Vegetables
- Pack size - 900g
- Batch code - All
- Best before - All codes between January 2020 and June 2020 inclusive
Growers Pride Supersweet Sweetcorn
- Pack size - 450g
- Batch code - All
- Best before - All codes to July 2021 inclusive
Oriental Express Chinese Chicken
- Pack size - 350g
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Oriental Express Chinese Prawns
- Pack size - 350g
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Oriental Express Egg Fried Rice
- Pack size - 350g
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Pinguin Country Vegetable
- Pack size - 1kg
- Batch code - All
- Best before - All codes to July 2020 inclusive
Pinguin Frozen Cut Beans
- Pack size - All
- Batch code - NA
- Best before - All codes to July 2020 inclusive
Growers Pride Mixed Vegetables
- Pack size - 750g
- Batch code - All
- Best before - All codes to July 2020 inclusive
Ross Mixed Vegetables
- Pack size - 450g
- Batch code - All
- Best before - All codes to July 2021 inclusive
Growers Pride Mixed Vegetables
- Pack size - 450g
- Batch code - All
- Best before - All codes to July 2021 inclusive
Ross Mixed Vegetables
- Pack size - 1kg
- Batch code - All
- Best before - All codes to July 2020 inclusive
Ross Sweetcorn
- Pack size - 450g
- Batch code - All
- Best before - All codes to July 2021 inclusive
Ross Sweetcorn
- Pack size - 1kg
- Batch code - All
- Best before - All codes to July 2020 inclusive
Tesco Frozen Mixed Vegetables
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Tesco Growers Harvest Frozen Mixed Vegetables
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
Tesco Frozen Sweetcorn
- Pack size - All
- Batch code - All
- Best before - All codes to Jan 2020 inclusive
