The number of E. coli, Salmonella, Campylobacter, and Listeria infections has gone up in Ireland, according to 2022 data from the Health Protection Surveillance Centre (HPSC).

During the COVID-19 pandemic, reporting rates for giardiasis, listeriosis, norovirus, rotavirus, salmonellosis, shigellosis, and toxoplasmosis in Ireland decreased compared to pre-pandemic levels. Still, rates for campylobacteriosis, cryptosporidiosis, E. coli, and yersiniosis increased or remained unchanged. In 2022, most of these diseases returned to or remained at pre-pandemic levels.

A 2021 cyber-attack at the Health Service Executive (HSE) also affected data validation and collection, reporting of enhanced data variables, and outbreak notification.

Campylobacter and Salmonella stats
In 2022, 3,617 Campylobacter cases were recorded. The incidence rate increased by 13 percent compared with 2021, after a rise of 23 percent between 2020 and 2021. Rates in 2021 and 2022 were the highest recorded in recent years and remained largely unaffected by the pandemic, apart from a slight decrease in 2020. In 2022, reporting rates were above the EU average.

The highest incidence rate was among those younger than 5, with males accounting for 61 percent of cases in this age group. The rate increased across all age groups 2022 except among 5-9 and 10-14-year-olds. The highest number of notifications was reported in June, with 474.

Ireland had between zero and three outbreaks a year from 2019 to 2022. In 2022, outbreaks ranged in size from two to 11 cases, with a median of three people ill.

342 Salmonella infections were recorded in 2022, and 142 people were hospitalized. The reporting rate in Ireland remained lower than the EU average.

The incidence rate decreased in 2020 and 2021 during the pandemic. In 2022, it almost doubled from 2021 but was similar to pre-pandemic rates.

The highest incidence rate was among less than one to 4 year olds. Salmonella Typhimurium, including monophasic Salmonella Typhimurium and Salmonella Enteritidis, were the most common serotypes 2022. Other frequently seen types included Newport, Poona, Mbandaka, and Infantis. Salmonella Enteritidis was more likely among travel-associated cases, but it was Salmonella Typhimurium among domestic infections.

In 2022, 99 patients reported being infected outside Ireland. Spain, Portugal, and Turkey were the most common countries among travel-associated cases.

Seventeen outbreaks were reported in 2022, up from 11 and six in 2020 and 2021. Three were national incidents, including 16 cases that were part of the Ferrero Kinder chocolate multi-country outbreak. Another Salmonella Typhimurium outbreak affected 27 people, but the source was not found.

E. coli and Listeria figures
980 E. coli cases were recorded in 2022, and 322 people were hospitalized. The notification rate remained higher than the EU average. In 2022, only the rate in Denmark was higher than in Ireland.

Key risk factors for infection include private well water, animal/environmental exposures, and attending a childcare facility. Food and international travel play minor roles, said HPSC.

Four deaths occurred among cases in 2022; the infection did not cause two, while the cause of death was not known for the other two. All people who died were older than 60.

In 2022, the incidence rate for E. coli increased by 3 percent compared to 2021. The highest rate was among less than one to 4-year-olds, followed by those more than 65 years old.

The top serogroup among culture-confirmed cases was O26 on 232 occasions, followed by O157 164 times. Other common serogroups were O145, O146, O103, and O91. Infections caused by E. coli O26 were more common earlier in the year, peaking in June, while those caused by O157 were more common later in the year.

Twenty-four cases of hemolytic uremic syndrome (HUS) were reported. Ten were O26, and six were O157, while O103, O145, O5, and O55 caused one case each.

Seventy-eight E. coli outbreaks were notified, with 208 people ill, compared to 62 outbreaks in 2021.

There were 18 cases of listeriosis in Ireland in 2022. Notifications decreased to six in 2020 but returned to usual levels in 2021 and 2022. Notification rates in 2022 were half the average rate in Europe.

In 2022, the highest incidence occurred in people older than 65 years old. There were also two cases in the less than 1 to 4-year age group. There was one pregnancy-related listeriosis notification each year in 2022, 2021 and 2020.

Ireland also recorded three cases each of Clostridium perfringens and Bacillus cereus and two of botulism in 2022. A total of 17 Yersinia infections were reported. Hepatitis A fell from 82 cases in 2021 to 66 in 2022.