Austria recorded an increase in the number of reported E. coli infections in 2021, based on the latest data.

In 2021, 1,437 specimens were processed at the National Reference Centre for E. coli. Overall, 1,286 human samples, 79 food, and 35 pet food samples were analyzed.

A total of 476 human stool samples tested positive for Shiga toxin-producing E. coli (STEC). Of these, 310 isolates were confirmed as Shiga toxin-producing compared to 242 in 2020.

In 2021, only 34 were E. coli O157 with the rest non-O157. Among the latter, there were 25 O26, 26 O103, three O111, and 12 O145 isolates. In the Austrian Epidemiological Notification System (EMS), 384 cases were reported, up from 304 in 2020.

In Upper Austria, 53 cases were reported to the EMS in 2020 compared to 104 in 2021. This same state sent 123 human samples to the National Reference Centre in 2020 versus 566 in 2021.

HUS and patient details
Eighteen cases of the hemolytic uremic syndrome (HUS), 12 female and six male, were diagnosed with 11 in children under the age of 15. Five of the 18 cases were caused by STEC O26:H11. This is up from 11 cases in 2020.

One was a 10-year-old girl from Upper Austria that was triggered by a STEC/enteroaggregative E. coli hybrid strain of O104:H4, which was very similar to a German outbreak strain of 2011.

There were 12 family outbreaks with two to five cases and one STEC O157:H7 outbreak with five cases because of contaminated drinking water reported in EMS.

Forty-six of the 1,286 human samples tested positive for the presence of enteropathogenic E. coli (EPEC). Three were positive for enteroinvasive E. coli (EIEC) and Enterotoxin E. coli (ETEC) were detected in four samples.

As in previous years, the most STEC cases reported in EMS occurred in the age group 0 to 4 years old with 107. Next are 5 to 14-year-olds and people over the age of 65. Most STEC-positive samples were registered in the summer months of July and August, but also in September.

One fatality was reported in the EMS. The patient was a 79-year-old woman from Upper Austria who had heart and kidney failure from diarrhea caused by STEC O91:H14.

Outbreaks summary

In 2021, 20 foodborne outbreaks with 92 patients were notified. A total of 27 people needed hospital treatment and two deaths were reported. In 2020, there were 21 outbreaks, 67 patients, and 17 hospitalizations.

Salmonella caused nine outbreaks with 61 cases this past year, followed by Campylobacter with six, four were due to STEC, and one by Listeria monocytogenes with five patients. Fifteen were considered household outbreaks and three were associated with foreign travel.

Salmonella Enteritidis was behind five outbreaks, while monophasic Salmonella Typhimurium, Salmonella Braenderup, Coeln, and Muenchen all caused one each.

The Salmonella Braenderup outbreak was part of a multi-country incident linked to melons from Honduras. Austria had 11 cases in five federal states.

A monophasic Salmonella Typhimurium outbreak sickened 31 people from seven states. A connection to a restaurant in Eastern Styria was established for 24 people. The outbreak strain was detected in various dishes served by the restaurant or in the petting zoo belonging to it. After the temporary closure of the restaurant and hygiene measures at the outlet and petting zoo, no further cases occurred.

Fatal Listeria incident
Campylobacter jejuni was the cause of five outbreaks, two were caused by Campylobacter coli, and both types were found in one household outbreak with two patients.

Serotypes STEC O26:H11, O146:H21, O157:H7 and O91:H14 were identified in E. coli outbreaks which sickened 14 people.

A Listeria outbreak affected five people between January 2020 and September 2021 with four cases in 2021. Two people died. Meat products from two processing companies in Lower Austria were identified as the source. Damaged areas on the floor were suspected as possible sources of contamination.

Travel-associated outbreaks included two Salmonella Enteritidis incidents with one after a stay in Romania. A STEC O91:H14 outbreak was reported after going to Turkiye for a family celebration.

Meat products except poultry were linked to a STEC O91:H14 and Listeria outbreak. Poultry meat other than chicken was suspected in Salmonella Enteritidis and Campylobacter coli epidemics and bakery products in two Salmonella Enteritidis outbreaks. Sweets and chocolate were suspected in an E. coli O146:H21 outbreak.

It had been previously reported that the number of human isolates sent to the National Reference Centre for Salmonella increased from 906 in 2020 to 1,048 in 2021.

A total of 6,019 cases of campylobacteriosis were reported in Austria and 36 cases of invasive listeriosis were recorded with seven people dying within 28 days of diagnosis.