Food-borne outbreaks

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Changed on: 24.07.2019

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 2017

Food-borne outbreaks in Austria 2017

In 2017, 69 food-borne outbreaks were reported throughout Austria. Since 2006, the number of outbreaks has decreased by 88.7%. In connection with the 69 outbreaks, 227 persons were affected, less than in 2016 (436 persons) and every year before. As a result, the incidence of affected persons in connection with food-borne outbreaks almost halved from 5.0 per 100,000 inhabitants in 2016 to 2.6 per 100,000 inhabitants in 2017. In 2006, 30.7 per 100,000 inhabitants were still affected by outbreaks in Austria.

The decrease in cases can be attributed to the fact that no major outbreak occurred; most individuals were affected by a norovirus outbreak (17 cases), eleven each of two S. Enteritidis PT8 and one C. jejuni outbreaks. Six outbreaks were reported in 2016, each involving more than 20 individuals, including one norovirus outbreak with 102 cases. In 2017, two deaths were associated with outbreaks (both in listeria outbreaks).

Jahr200620072008200920102011201220132014201520162017
food-borne outbreaks60943836835119323212213396788069
- of which by salmonella45230522320898100534447343731
- of which by Campylobacter13710811812082116615840324024
Number of patients (in connection with food-borne outbreaks)2.5301.7151.3761.330838789561568790333436227
- in connection with outbreaks Sick per 100,000 residents30,720,716,515,910,09,46,76,79,33,95,02,6
- of which hospitalized49328633822315517997108121866856
- Number of deaths310620001002

Types of food-borne outbreaks

The Austrian Zoonoses Act obliges the AGES to collect the outbreak data annually and forward them to the EU. Certain classifications apply to this reporting: Outbreaks affecting only members of a single household are classified as budget outbreaks. If persons from more than one household are affected, this is counted as a general outbreak. Most household outbreaks occur every year because it is often impossible to epidemiologically link outbreaks of different household outbreaks by identifying a single causal food. In 2016, 77.5 percent 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

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Food-borne outbreaks, 2006 - 2015
Food-borne outbreaks, 2006 - 2015
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How does Salmonella get into humans?
Top 10 of the most important pathogens
Foods that caused 2014 outbreaks

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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