Foodborne Illness

A key priority for Food Standards Scotland is to protect consumers in Scotland from the risks of foodborne illness.

Our approach

How FSS aims to protect consumers is laid out in the Foodborne Illness Strategy which targets the key pathways that are responsible for the transmission of microbiological, chemical and radiological risks throughout the food chain. It builds on existing programmes of work but proposes a slightly different approach to those previously taken forward which were either designed around individual food commodities, or focussed on control measures for specific contaminants. The proposed framework allows contamination risks to be viewed in a more holistic manner and aims to identify the key transmission pathways at which interventions are likely to have the greatest potential for preventing or controlling contamination of the food chain and reducing the risks to human health.

Regulations exist to ensure food businesses take appropriate steps to control food safety risks before products are placed on the market. To support food safety management, we apply a ‘farm-to-fork’ approach; to try to ensure contamination is minimised as much as possible during the production and processing of food before it reaches the kitchen. We also promote good food hygiene practices through the development of guidance for Scottish food businesses and caterers; and we also provide consumer guidance. All of our work is supported by research to ensure all of our strategies and interventions are effectively targeted and evidence based.

Main causes of foodborne illness in Scotland

In Scotland, it is estimated there are 43,000 cases of foodborne illness annually, with 5,800 GP presentations and 500 hospital admissions. FSS works closely with the Food Standards Agency (FSA) and Scottish partners such as Health Protection Scotland (HPS) to target the bacterial and viral pathogens which cause the highest number of cases of foodborne illness.

HPS is responsible for undertaking surveillance of infectious intestinal disease (IID) caused by the key pathogens of interest. This surveillance records the total number of cases of IID which have been acquired through the food chain and other sources such as contaminated water or the environment. The table below shows the contribution made by the top five pathogens associated with IID in Scotland.

Pathogen

Total number of cases reported in 2015 through national surveillancea

Estimated under-reporting rate

Estimated number of cases in the community in 2015b

Campylobacter

6260

9.3c

58,218

Salmonella

802

4.7c

3769

E. coli O157

183

1.0d

183

Listeria monocytogenes

13

1.0d

13

Norovirus

1389

288c

400,032

a - Health Protection Scotland (HPS) are responsible for the collecting and reporting of case data.

b - The estimated number of cases is calculated by applying the under reporting ratio to the number of cases reported through national surveillance.

Campylobacter

Campylobacter is the most common form of foodborne illness in Scotland (a situation which is similar to the UK and most of the developed world). Illness usually lasts around a week and is characterised by diarrhoea, abdominal pain and fever, and, in some cases, nausea and vomiting. For some patients, campylobacter can result in much more serious illness post infection, including irritable bowel syndrome (IBS), reactive arthritis and, in rare cases, Guillain-Barré syndrome – a serious condition of the nervous system. At its worst, campylobacter can kill.

Recently, HPS has published that has been a decline in the number of laboratory reports of campylobacter for the second consecutive year with 5296 reports in 2016, a decrease of 15.5% compared to 2015 and 20.4% compared to 2014.

FSS has commissioned research with the University of Aberdeen to improve our understanding of the most important causes of campylobacter in humans in the Scottish population. The results of this research indicate that the types of campylobacter identified in human infection in Scotland are most closely associated to those found in raw chicken (55-75%), followed by cattle (10%), sheep (10-22%), pigs (0-8%) and wild birds (4-8%).

This research provides evidence that the most important source of infection is chicken, which has either been consumed raw or undercooked or has spread campylobacter to other foods through cross-contamination. Read the full report here.

FSS has been working closely with Food Standards Agency (FSA) and industry to tackle the levels of campylobacter in UK produced chicken to reduce the number of foodborne campylobacter infections. A voluntary slaughterhouse target of less than 10% of poultry leaving processing plants with the highest levels of contamination (>1000 cfu/g) was agreed.

Poultry producers, retailers and other stakeholders have worked to identify and implement effective interventions for controlling campylobacter at all stages of the food chain. The latest findings from the survey of chilled, whole chickens at retail has shown that excellent progress has made, with 56% of chickens testing positive for the presence of campylobacter (down from 78% in 2014) and 7% of chickens within the highest band of contamination. The larger retailers and major processors have all made significant investments and improvements in their processes and many have achieved the target set to reduce the highest levels of campylobacter contamination. Therefore focus will now move to encouraging and working with smaller retailers and processors who generally do not meet the target levels and have not had the same levels of improvements made to their processing lines.

FSS are also collaborating with other partners in Scotland including HPS and Scottish Government to understand how people in Scotland can become infected with campylobacter through other exposure routes such as the environment and identify ways that they can protect themselves from the risks.

FSS has produced a campylobacter factsheet for caterers and other small businesses.

Shiga toxin-producing E. coli (STEC)

Shiga toxin-producing E. coli is commonly referred to as STEC and is also synonomous with verotoxin producing E. coli (VTEC). There are many different STECs including E. coli O157.

STEC is an important public health challenge in Scotland, as it continues to cause outbreaks of infection, severe illness and, in some cases, death, particularly among the very young. Clinical aspects of infection STEC infection can be asymptomatic, or cause a spectrum of illness ranging from mild diarrhoea, bloody diarrhoea and haemorrhagic colitis. Haemolytic uraemic syndrome (HUS), a consequence of STEC which can lead to kidney failure is more likely in those aged under 16 or over 60 years.

With over 160 cases of E. coli O157 each year, Scotland has consistently recorded the highest rates of infection per 100,000 head of population in the UK since the late 1980s. Non-domestic animals, particularly ruminants, are the main reservoir of the organism, which rarely causes disease in livestock. Infection occurs when humans ingest organisms originating from animal faeces, most directly by contact with grazing animals, their environments or contaminated food or water.

Two large outbreaks of E. coli O157 infection (Wishaw 1997 and South Wales 2005) resulted from poor cross-contamination controls by Butchers, which lead to the spread of the pathogen to ready to eat food from contaminated raw meat. FSS are the in the process of producing guidance on the steps for food businesses to take in order to control cross-contamination between raw foods that are a potential source of E. coli O157 and ready-to-eat foods. Until this guidance is finalised, you can access FSA’s cross-contamination guidance here.

In November 2013, Scottish Government’s VTEC/E. coli O157 Action Plan for Scotland was published, which sets out 86 recommendations designed to tackle STEC/E. coli O157 infection in Scotland. FSS has been working, as a member of the multi-agency Action Group, to consider ways to disrupt the transmission routes for STEC from source to humans and has sole or joint responsibility for 23 of the recommendations. Good progress has been made on addressing these recommendations through improving STEC controls at primary production, monitoring of contamination at abattoirs, implementation of the cross-contamination guidance and robust enforcement of controls at butchers and caterers across Scotland, communication of food hygiene messages to consumers, and research to improve our understanding of the pathogen and risks in the food chain.

Listeria monocytogenes

The public health importance of Listeria monocytogenes as a gastro-intestinal pathogen arises not from the number of reported cases, which is relatively low (10-20 cases annually in Scotland) compared with many other pathogens, but rather due to the severity of infection, high mortality, and the fact that it is foodborne. Infection with Listeria monocytogenes causes influenza like illness, septicaemia or a meningo-encephalitis. Pregnant women, newborn infants, the elderly and immunocompromised individuals are most at risk.

Due to the long incubation period for Listeria monocytogenes (up to 90 days) it is difficult to determine the key sources of infection from traditional epidemiological methods. However, listeria bacteria has been found in a range of chilled ready to eat foods including, pre-packed sandwiches, pate, smoked salmon, soft cheeses and cooked sliced meats.

Our work is aimed at reducing the risks of Listeria monocytogenes in the production, storage and handling of chilled ready to eat foods which are most commonly associated with human illness. A key priority is to identify effective measures for controlling the organism in the production of ready to eat foods and developing tools to assist food businesses and high-risk food sectors.

We have produced an online tool to help smoked fish producers manage the risk of contamination of their product by Listeria monocytogenes, which is often found in the production areas of manufacturers of smoked fish. This initiative aims to help producers of these foods to follow best practice so they can reduce the risk of contamination of their products.

It is also a priority for us to ensure information about risk and avoidance is communicated effectively so listeriosis can be prevented among high-risk groups. We have collaborated with FSA to provide guidance for staff with responsibility for providing food in hospitals, nursing homes, etc. to allow them to identify and manage the critical control points specific to controlling Listeria in the food supply chain, with the ultimate aim of reducing the risk of vulnerable groups contracting listeriosis in these settings. This guidance was published in October 2016 and is available here.

Salmonella

Salmonella is the second most commonly reported cause of bacterial infectious intestinal disease in Scotland after campylobacter; there were 803 reported cases in 2015. Common symptoms include diarrhoea, stomach cramps, nausea, fever and occasionally vomiting. These symptoms usually last 4-7 days and clear up without treatment.

Salmonella can cause illness through a number of routes including contaminated food, environmental exposure, or transmission from infected animals.

During the late 1990s, when vaccination against Salmonella Enteritidis was introduced in the poultry industry, there was a 37% decrease in the number of cases of Salmonella in Scotland, and in following years the numbers have continued to decline annually. However it remains an important pathogen and is responsible for a large number of outbreaks each year, especially from eggs originating from unvaccinated flocks.

EU Regulation requires Member States to take effective measures to detect and control Salmonellas of public health significance in specified animal species at all relevant stages of production. National Control Programmes have been established in the UK to reduce the prevalence of Salmonella in poultry and pigs at primary production level. They cover farm animal species which present a potential risk of transmitting Salmonella and other zoonotic agents to humans.

Foodborne viruses

The virus which is most commonly linked to food is norovirus, which is also known as the ‘winter vomiting disease’, although it can occur at any time of year. There were 1390 reported cases in 2015 with infection usually causing a mild, short lived illness (which usually lasts 12-60 hours) characterised by sudden onset nausea followed by projectile vomiting and diarrhoea. Dehydration may occur and hospital treatment is sometimes necessary, particularly for the young and elderly.

Norovirus is highly infectious, and person-to-person spread accounts for a high proportion of cases, with outbreaks common in semi-closed settings including carehomes, schools, nurseries, hotels and cruise ships. However, norovirus infection can also occur through contact with contaminated environments or eating food which has been grown in or treated with contaminated water (e.g. shellfish or fresh produce). FSS are currently participating in the EU baseline survey of norovirus in oysters. Additionally, norovirus can be passed on by an infected food handlers and therefore those working in the food industry should adhere to the Fitness to work guidance.

Other causes of foodborne illness

Marine biotoxins

Biotoxins can be produced by certain species of naturally occurring marine phytoplankton, and detected levels are higher in summer months. Food Standards Scotland has a monitoring programme in place that regularly monitors shellfish harvesting waters and closes areas where biotoxins are detected at levels which exceed the legal limit. The four main groups of marine biotoxins which are monitored in Scotland can cause the following illnesses:

Amnesic Shellfish Poisoning (ASP)

Caused by the neurotoxin domoic acid (DA) and its variants. ASP is characterized by gastrointestinal disorders (vomiting, diarrhea, abdominal pain) with higher doses leading to more serious neurological problems (confusion, short-term memory loss, disorientation, seizure, coma), particularly in elderly patients.

Diarrhetic Shellfish Poisoning (DSP)

Caused by a group of lipophilic toxins including okadaic acid, and dinophysistoxins (collectively known as DSTs). DSP generally causes mild gastrointestinal disorders which can last from 2-3 days including nausea, vomiting, diarrhoea, and abdominal pain, which can be accompanied by chills, headache, and fever.

Azaspiracid shellfish poisoning (AZP)

Caused by the lipophillic toxin azaspiracid and several derivatives (AZAs). To date, more than 30 AZA analogs have been identified, with three analogs routinely monitored in shellfish. Symptoms are predominantly gastrointestinal disturbances resembling those of diarrhetic shellfish poisoning and include nausea, vomiting, stomach cramps, and diarrhea. Illness is self-limiting, with symptoms lasting 2 or 3 days.

Paralytic Shellfish Poisoning (PSP)

Caused by a group of water soluble neurotoxins that are collectively referred to as saxitoxins or paralytic shellfish toxins (PSTs). PSP causes neurologic symptoms ranging from a tingling of the lips, mouth, and tongue to numbness, weakness, dizziness, and headache; and in severe cases can lead to respiratory paralysis and death.

Further information on marine biotoxins, our shellfish monitoring programme, and guidance on shellfish safety can be found on our Shellfish pages.

Chemical and Radiological contaminants

Foodborne illness can also occur following the consumption of food or drink that has become contaminated with either naturally occurring or man-made chemicals. Food Standards Scotland works with FSA and other government agencies to assess the potential food safety risks arising from chemical contaminants and take appropriate action to protect public health.

Radioactivity exists naturally in the environment and is also created by human activity such as nuclear power stations and military operations. Inevitably some of this enters the food chain and levels are strictly monitored and controlled to protect public health.

For more information, see our Contaminants page.

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