Austria saw a decline in Salmonella and Campylobacter infections in 2020, according to annual figures released recently.
The country also reported data for Listeria, botulism poisoning and Yersinia which were at about the same levels as the year before.
This past year, the number of primary human isolates sent to the National Reference Centre for Salmonella (NRZS) decreased by 51.6 percent compared to 2019. In total, 906 Salmonella isolates from 905 infected people were sent to the NRZS. In 2019, the figure was 1,872 primary isolates.
The number of Salmonella isolates in 2019 was significantly higher than previous years because of an outbreak across federal states that affected more than 300 people caused by eggs from Poland. However, the coronavirus pandemic and associated measures also meant the number of submissions fell substantially, according to the report.
Salmonella Enteritidis was the most frequent serovar with 393 human isolates while 166 were Salmonella Typhimurium, including the monophasic variant. Third was Salmonella Coeln followed by Salmonella Infantis.
There was no cross-federal state foodborne disease outbreaks caused by Salmonella but there were 40 outbreaks that affected 90 people.
In 2020, there were 5,162 cases of campylobacteriosis reported. The annual incidence decreased by almost 22 percent compared to the previous year.
More than 90 percent of 5,151 isolates were Campylobacter jejuni and 8 percent were Campylobacter coli.
An increase of infections was recorded in the summer months, with most cases in June to August and an annually recurring, short-term rise in January. In March to May and October to December, the number of infections fell significantly below the previous year and the five-year average.
The age group most affected was zero to 4 years old, followed by 15 to 24 year olds. Men were more likely to develop campylobacteriosis than women.
In total, 130 people were infected abroad with two thirds of them in the first quarter of 2020. Imported cases of illness came from 42 different countries including Italy, Croatia, Thailand, Morocco and Germany.
It is likely the decrease in the reported and diagnosed Campylobacter infections in the year is largely indirectly because of measures taken to contain the COVID-19 pandemic, said officials.
Five Listeria clusters; one multi-country event
A total of 40 cases of invasive listeriosis were recorded, three of them pregnancy related, compared to 38 cases in 2019. In 2020, 12 people died in the 28 days after the samples were taken, including a newborn baby.
The highest incidence rate was in the age group above 65 years old but people ranged in age from zero to 89 years old. More than half of all cases were female.
In 2020, the National Reference Center for Listeria identified five illness clusters, which are defined as at least two isolates indistinguishable from each other.
The first cluster included four isolates from three patients. Blue cheese was mentioned as the possible source of infection during a patient survey but this couldn’t be confirmed by microbiological analysis. The last illness was in May 2020.
The second featured three isolates from two people in Carinthia and Lower Austria with the latest in May 2020. It was similar to an outbreak strain that affected six people in 2019. A food isolate taken from chicken wings in 2019 was closely related to the outbreak strain but an epidemiological connection could not be established. The third involved three human isolates from Vienna in March, September and October 2020. An isolate from 2018 clustered with cases of illness but no food source was found.
Next, in December 2020, the Austrian Agency for Health and Food Safety (AGES) learned of a cross-border listeriosis outbreak which affected two people in the federal states of Carinthia and Upper Austria, 42 people in Germany, one in Switzerland and two in Denmark. It was linked to Nautica smoked trout fillets from Denmark.
The final cluster included two patient isolates from Vienna and Upper Austria with the most recent in December 2020. Fourteen food-associated isolates from lettuce or surfaces touched by lettuce were similar to human isolates. Occurrence of isolates indistinguishable from one another doesn’t mean there is a causal relationship; there must also be an epidemiological link between cases and the food or food business.
One botulism report and Yersinia data
One case of botulism was documented this past year. Samples from a 31-year-old South Korean man temporarily working in Hungary yielded Clostridium botulinum neurotoxin.
In August 2020, the man was hospitalized in Vienna with symptoms typical of botulism poisoning. Clostridium botulinum neurotoxin was detected in a serum sample using a mouse bioassay. There was no subtyping of the neurotoxin and the source of infection could not be determined.
In 2019, the National Reference Center for Botulism in the country recorded two cases in six month old babies in Upper Austria. The year before, Clostridium botulinum type A was detected in a woman from Poland who lived in Upper Austria.
The National Reference Centre for Yersinia received 174 primary isolates of Yersinia spp. Of the human isolates, 93 were pathogenic and 81 non-pathogenic. Among the pathogenic ones, 92 belonged to Yersinia enterocolitica and one to Yersinia pseudotuberculosis.
More than 10 isolates were recorded in January, March and August. Males and females aged 5 to 14 years old were mostly affected.
A total of 128 cases of yersiniosis were reported to the Federal Ministry of Social Affairs, Health, Care and Consumer Protection in 2020 which is slightly higher than the year before.
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