Food-borne outbreaks

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Changed on: 04.10.2021

The consumer expects hygienically perfect food and the food industry attaches great importance to the quality of its products. If people nevertheless fall ill as a result of eating food contaminated with pathogens, then an attempt should be made to find out the causes.

In individual cases, it is usually not possible to find the cause of the disease among the variety of food consumed. If, however, there are group diseases, so-called food-borne outbreaks, there is a better chance of finding the food that served as the transmission vehicle for the infectious agent by working out characteristic similarities between the cases.

Since 2010, the documented food-borne outbreaks have been published annually in the AGES zoonosis Reports.

More information

The consumer expects hygienically perfect food and the food industry attaches great importance to the quality of its products. If people nevertheless fall ill as a result of eating food contaminated with pathogens, then an attempt should be made to find out the causes.

In individual cases, it is usually not possible to find the cause of the disease among the variety of food consumed. If, however, there are group diseases, so-called food-borne outbreaks, there is a better chance of finding the food that served as the transmission vehicle for the infectious agent by working out characteristic similarities between the cases.

Since 2010, the documented food-borne outbreaks have been published annually in the AGES zoonosis Reports.

More information

Situation in 2020

Foodborne outbreaks in Austria 2020

In 2020, a total of 21 foodborne illness outbreaks were reported, 27 fewer than in 2019. In total, 67 people were affected by the outbreaks, significantly fewer than the 793 people in the previous year. 17 people required hospitalization in connection with the outbreaks (2019: 159), and there were no deaths (2019: 1 death). 5 outbreaks were general outbreaks as opposed to 16 household outbreaks. Campylobacter emerged as the most common outbreak agent (10 outbreaks, 26 people affected), in one of these outbreaks C. jejuni and VTEC O157:H7 were simultaneously isolated from the two patients. Salmonella was second (7 outbreaks, 28 cases), and one outbreak each was due to VTEC (6 cases), TBE virus (3 cases), Listeria monocytogenes (2 cases), and Brucella melitensis (2 cases). Three of the 21 foodborne illness outbreaks can be classified as strong evidence outbreaks. The listeriosis outbreak(L. monocytogenes IIa, cluster 4 - 2020 (Ny9 UI-687) with 2 cases in Austria, affected 47 people across Europe, caused by smoked trout fillets produced in Denmark. Another outbreak (12 cases) was caused by consumption of poultry meat contaminated with S. Enteritidis from a take-away/snack bar. One TBE virus outbreak in three individuals was caused by consumption of raw goat milk and raw goat milk cheese.

Four outbreaks were acquired abroad, one caused by the pathogen Brucella melitensis, probably after consumption of sheep meat in Croatia, and one outbreak of salmonellosis(S. Enteritidis) after a stay in Poland (food unknown).

Year200620072008200920102011201220132014201520162017201820192020
Foodborne outbreaks60943836835119323212213396788069524821
- thereof due to salmonella4523052232089810053444734373121177
- thereof due to Campylobacter13710811812082116615840324024242210
Number of cases (linked to foodborne outbreaks)2.5301.7151.3761.33083878956156879033343622722279367
- outbreak-related cases per 100,000 inhabitants30,720,716,515,910,09,46,76,79,33,95,02,62,590,7
- of which treated in hospital493286338223155179971081218668565815917
- Number of deaths310620001002010

Figure 1: Number of detected foodborne outbreaks and outbreak cases per 100,000 population, Austria 2006-2020

Figure 2. proportion of outbreaks per pathogen, 2004-2020.

Types of foodborne outbreaks

The Austrian Zoonoses Act obliges AGES to collect and report outbreak data to the EU on an annual basis. Certain classifications result for this reporting: Outbreaks where only members of a single household are affected are considered a household outbreak. If people from more than one household are affected, this is counted as a general outbreak. Household outbreaks account for the majority each year because it is often not possible to link cases of illness from different household outbreaks epidemiologically by identifying a single causative food. In 2020, 76% of all outbreaks were classified as household outbreaks.

Outbreak Clarification

The aim of the outbreak survey is not only to stop the current outbreak, but above all to generally prevent such diseases in the future.

Through a detailed and systematic search, it will be possible to identify both the infection vehicle, i.e. the food that transmitted the infectious agent to humans, and the reservoir that represents the habitat in which an infectious agent normally lives. Only then is it possible to make targeted and meaningful interventions. These measures should result in the elimination of the cause of the outbreak, namely the infectious agent, from the food chain and the consumers no longer being exposed to this agent.

The following historical example illustrates the preventive medical potential of an outbreak clarification: In July 2004 it was possible to investigate a food-borne outbreak caused by Salmonella Enteritidis phage type 36, a very rare type of salmonella in Austria, which affected 38 people in four provinces, and to trace it back to a herd of laying hens. The flock was eradicated, the farm thoroughly cleaned and disinfected, and new laying hens were then kept. As a result of these measures, not a single case of Salmonella Enteritidis phage type 36 has become known in Austria since then.

 

 

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Picture: Human cases of disease caused by S. Enteritidis phage type 36, Austria 2000-2015

Implementation

In accordance with the provisions of the Epidemic Act, the locally competent district administrative authorities must immediately initiate the surveys and investigations necessary to determine the disease and the source of infection through the official physicians available to them for each report and suspicion of the occurrence of a notifiable disease - and thus also in the case of food-borne outbreaks. In addition, the Zoonoses Act 2005 requires the relevant competent authorities to investigate food-borne outbreaks and, where possible, to carry out appropriate epidemiological and microbiological investigations.

The authorities have the possibility to call in experts. In the past, the mere intensification of unspecific food sampling has repeatedly proven to be unsuccessful. In many outbreaks, the causative food (or the contaminated batch of the causative product concerned) is no longer available for microbiological testing at the time of the surveys.

In these cases, an epidemiological study can provide information that will enable preventive measures to be taken to avoid similar incidents in the future. The knowledge gained from successfully clarified national and international outbreaks in recent years has undermined the need for and benefits of epidemiological investigations.

 

 

Infographics

Thematic report on food-borne infectious diseases

Many authorities and institutions from different fields are involved in the monitoring of the food chain. Due to the complexity and the partly different objectives, a comprehensive, joint consideration is absolutely necessary. The 4th report from the series AGES WISSEN AKTUELL, "Food-borne Infectious Diseases", offers this overview. In addition, it describes which causes can lead to contamination of animal foodstuffs with certain pathogens and which measures for a reduction are possible for both producers and consumers.

In Austria, around 8,000 food-borne diseases are recorded each year in the national epidemiological reporting system (EMS). According to the WHO definition, food-borne infectious diseases are "infectious or toxic diseases that can actually or probably be attributed to the consumption of food or water".

A total of over 250 pathogens and toxins are known to cause such diseases. This report is limited to 20 pathogens of importance in Austria (Campylobacter, Clostridium difficile, EHEC/VTEC, Listeria, Salmonella, Shigella, Vibrionen, Yersinia, Noroviruses), Rotaviruses, sapoviruses, hepatitis viruses, Cryptosporidium parvum, Toxoplasma gondii, Cyclospora cayetanensis, Giardia and the toxins Staphyloccus aureus, Bacillus cereus, Clostridium botulinum, Clostridium perfringens). Pathogens that are virtually non-existent in Austria or occur only as travel sickness were not taken into account.

Since 2009, bacterial and viral food infections and poisoning have been reported via the EMS, a comprehensive surveillance system. However, these reporting figures must be considered in a differentiated manner: Numerous factors can lead to an underestimation of the actual number of cases ("underdetection/underreporting"). For salmonella, for example, data are available from Europe-wide basic studies, monitoring and control programmes. The reduction of salmonellosis is an effect of measures taken on the basis of this data. Toxoplasmosis, on the other hand, does not have to be reported, although new scientific findings indicate a connection with food. All these factors must be taken into account when assessing the real public health significance of a disease.

AGES WISSEN AKTUELL 4/2016: Food-borne infectious diseases


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