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2023 Data for Zoonoses in Ireland

Overview of 2023 Zoonoses Data

Introduction

Zoonoses refer to diseases and infections that can be transmitted between animals and humans. Transmission may occur through direct contact with animals or indirectly via exposure to animal excreta, such as faeces, which can contaminate food, water, or the environment. Foodborne zoonotic diseases arise from the consumption of food or water that has been contaminated with zoonotic pathogens, including bacteria and their toxins, viruses, and parasites. These pathogens typically enter the body through the gastrointestinal tract, where initial symptoms often manifest. Many of these microorganisms are found in the intestines of healthy food-producing animals. The potential for contamination exists throughout the food production process from the farm to the consumer. This necessitates effective prevention and control measures across the entire food chain. While anyone can be infected by a zoonotic pathogen, certain populations, particularly young children, the elderly, and individuals with compromised immune systems are more vulnerable and face a higher risk of severe health outcomes.

The control and elimination of zoonoses in humans and animals presents challenges. However, the impact of zoonoses on health can be mitigated through: (i) monitoring the reservoirs of infectious zoonotic pathogens to better understand and manage their transmission; (ii) implementing hazard control measures along the food chain by businesses; and (iii) providing public education aimed at reducing the risk of infection.

The European Union (EU) Zoonoses Directive (Directive 2003/99/EC) requires Member States to collect data on zoonoses. The Directive requires reporting at EU level on eight zoonoses (i.e. List A, Annex I) with reporting on additional zoonoses based on the epidemiological situation in the Member State (i.e. List B, Annex I). Annual EU summary reports are jointly published by the European Food Safety Authority (EFSA) and the European Centre for Disease and Prevention Control (ECDC). The latest report, at time of publication, is for the 2023 data (EFSA and ECDC, 2024).

The Irish zoonoses report is published annually by the FSAI, in collaboration with the Department of Agriculture, Food and the Marine (DAFM), the Health Service Executive (HSE), the Local Authority Veterinary Service (LAVS), the Sea-Fisheries Protection Authority (SFPA) and the Health Protection Surveillance Centre (HPSC). The report brings together the results of thousands of tests carried out on samples of food and feed, as well as tests on material of animal or human origin, in an effort to determine the pattern and extent of infection by zoonotic pathogens transmitted to humans from animals. 

Please be advised that the human zoonoses figures for 2023 are provisional and may be revised in the following years. This is due to ongoing updates based on the notification data in the HPSC’s Computerised Infectious Disease Reporting (CIDR) system.

The data presented in the 2023 tables concerning the results of Irish testing conducted on food, animal, and animal feed samples is categorised into four distinct types: routine, census, objective, and suspect sampling (EFSA, 2024):

  • Routine sampling is considered as planned sampling, though it does not utilise statistically random methods.
  • Census sampling refers to the comprehensive assessment of an entire population on which the data is based.
  • Objective sampling involves the deliberate selection of a random sample that is statistically representative of the population under analysis. 
  • Suspect sampling is an unplanned approach where individual units are chosen based on recent judgment and experience related to the population, lot, or sampling frame, such as prior positive samples. The samples obtained from suspect sampling may have a higher likelihood of having pathogens present. 

Overview of 2023 data

Brucellosis

  • In Ireland, there were 5 notified cases of brucellosis in 2023, resulting in a CIR of 0.09 per 100,000 population (HPSC, 2024). This disease ranked tenth in terms of incidence among the various zoonoses reported.
  • During 2023, a total of 107,621 bovine herds, and 50,983 ovine and caprine herds, were tested for the presence of Brucella. None of the herds were identified as infected. All herds were classified with the status of being officially free from the disease. 
  • In addition to the bovine, ovine and caprine herds tested, a total of 1,282 animal samples were tested under objective sampling in Ireland. None of the tested samples were positive for Brucella.

Campylobacteriosis

  • In Ireland, a total number of 3,737 reported cases of human campylobacteriosis were reported in 2023, equating to a crude incidence rate (CIR) of 70.76 cases per 100,000 population (HPSC, 2024). This disease ranked first in Ireland in terms of incidence compared to the other zoonoses evaluated.
  • During 2023, a total of 191 routine food samples (meat n=188; other foods n=3) and 42 suspect food samples (meat n=17; other foods n=25) were tested for the presence of Campylobacter spp. Campylobacter was detected in:
    • 112 (59.6%) of the 188 routine meat samples. All positive samples were obtained from broiler carcasses (n=112).
  • During 2023, a total of 2,162 animal samples were tested for Campylobacter, 127 of which were positive (5.9%). Infected animals included calves under one year of age (n=87), curlew (n=1), dogs (n=3), and sheep (n=36).

Cryptosporidiosis

  • In Ireland, there were 870 reported cases of cryptosporidiosis in 2023, resulting in a case incidence rate (CIR) of 16.47 per 100,000 population (HPSC, 2024). This disease recorded the third highest incidence compared to the other zoonoses evaluated.

Echinococcosis

  • In Ireland, there were no reported cases of echinococcosis in 2023 (HPSC, 2024).

Leptospirosis

  • In Ireland, there were 44 notified cases of leptospirosis in 2023, resulting in a CIR of 0.83 per 100,000 population (HPSC, 2024). This disease ranked sixth in terms of incidence compared to the other zoonoses evaluated.

Listeriosis

  • In Ireland, there were 18 notified cases of listeriosis in 2023, resulting in a CIR of 0.34 per 100,000 population (HPSC, 2024). This disease ranked ninth in terms of incidence compared to the other zoonoses evaluated.
  • During 2023, a total of 1,398 routine food samples (meat n=238; other foods n=1,160) and 77 suspect food samples (meat n=13; other foods n=64) were tested for the presence of Listeria monocytogenes. L. monocytogenes was not detected in any of the suspect meat samples; however, it was detected in 24 samples from the remaining food categories. These included:
    •  6 (2.5%) of the 238 routine meat samples. The positive samples included beef (n=3) and pork (n=3) meat products.
    • 14 (1.2%) of the 1,160 routine samples from other foods. The positive samples originated from cheeses made from raw cow’s milk (n=4), fish (n=5), RTE salads (n=3), and other processed food products/prepared dishes (n=2).
    • 4 (6.2%) of the 64 suspect samples from other foods. The positive samples originated from cheese made from raw cow’s milk (n=1), fish (n=2), and other processed food products/prepared dishes (n=1).
      A total of 3,903 routine food samples (meat n=1,337; other foods n=2,566) and 243 suspect food samples (meat n=89; other foods n=154) were tested for the enumeration of Listeria monocytogenes. L. monocytogenes was enumerated from 18 samples. These included:
    • 8 (0.6%) of the 1,337 routine meat samples. The enumerated samples included beef (n=2), poultry (n=4) pork (n=2) meat products.
    • 6 (1.2%) of the 2,566 routine samples from other foods. The enumerated samples included bakery products (n=1), crustaceans (n=1), and other processed food products/prepared dishes (n=4).
    • 2 (2.2%) of the 89 suspect meat samples. The enumerated samples originated from poultry meat products (n=2).
    • 2 (1.3%) of the154 suspect samples from other foods. The enumerated samples originated from an RTE salad (n=1) and a processed food product/prepared dish (n=1).
  • Of the 4,146 enumeration tests (number of colony forming units per gram), L. monocytogenes was present in 1 (0.02%) of routine samples at >100 cfu/g. The microbiological criteria for L. monocytogenes in Commission Regulation (EC) 2073/2005, as amended, sets a legislative limit of 100 cfu/g for certain categories of RTE food products during their shelf life when they are placed on the market. The positive routine sample with enumerated levels of L. monocytogenes >100 cfu/g was a RTE food. 
  • During 2023, a total of 4,543 animal samples were tested for L. monocytogenes, 51 of which were positive (1.1%). Infected animals included cattle (n=41) and sheep (n=10).

Q fever 

  • In Ireland, there were no reported cases of Q fever in 2023 (HPSC, 2024).
  • During 2023, a total of 1,273 animal samples were tested under objective (n=1,273) and suspect (n=1) sampling for the presence of Coxiella. Coxiella was detected in 54 samples. These included:
    • 53 (5.3%) of 1,007 dairy cows.
    • 2 (1.1%) of 190 sheep.

Salmonellosis

  • In Ireland, a total of 406 cases of salmonellosis were reported in 2023, equating to a CIR of 7.69 cases per 100,000 population (HPSC, 2024). This disease ranked fourth in terms of incidence compared to the other zoonoses evaluated.
  • During 2023, a total of 2,962 routine food samples (meat n=885; other foods n=2,077) and 220 suspect food samples (meat n=88; other foods n=132) were tested for the presence of Salmonella spp. Salmonella was detected in:
    • 24 (2.7%) of the 885 routine meat samples. The positive samples included carcases from broilers (n=2) and pigs (n=13); fresh meat from broilers (n=2) and pig (n=1); and meat preparations from broilers (n=2), duck (n=1), pigs (n=2), and other animal species or not specified (n=1).
    • 1 (0.05%) of the 2,077 routine samples from other foods. The positive sample originated from a ready-to-eat (RTE) salad. 
    • 1 (1.1%) of the 88 suspect meat samples. The positive sample originated from poultry meat product specified as RTE.
    • 1 (0.8%) of the 132 suspect samples from other foods. The positive sample originated from a sesame seed product or similar of unspecified RTE status.
  • Salmonella 1,4,[5],12:i:- (44.4%, n=24/54) was the predominant serotype reported from food isolates in 2023.
  • During 2023, a total of 4,917 animal samples were tested under objective (n=4,904) and suspect (n=13) sampling for the presence of Salmonella. Salmonella was detected in 124 samples. These included:
    • 41 (3.2%) of 1,286 aborted calves.
    • 24 (2.5%) of 963 sheep.
    • 20 (3.1%) of 643 pigs.
    • 6 (2.5%) of 237 adult cattle over 2 years of age.
    • 22 (1.7%) of 1,330 calves under 1 year of age.
    • 2 (0.5%) of 424 of poultry and wild birds.
  • In addition, poultry flocks were tested for Salmonella under industry (census) sampling and under official (objective) sampling in 2023. Of official sampling:
    • 138 broiler breeder flocks of Gallus gallus (parent breeding flocks) were tested with no positive flocks.
    • 76 broiler flocks before slaughter were tested with 2 positive flocks.
    • 351 laying hen flocks were tested with 2 positive flocks.
    • 4 turkey breeder flocks were tested with no positive flocks.
    • 13 turkey fattener flocks tested with 2 positive flocks.
  • Of industry sampling:
    • 138 broiler breeder flocks of Gallus gallus (parent breeding flocks) were tested with 3 positive flocks.
    • 3,658 broiler flocks before slaughter were tested with 57 positive flocks.
    • 465 laying hen flocks were tested with no positive flocks.
    • 4 turkey breeder flocks were tested with no positive flocks.
    • 461 turkey fattener flocks tested with 7 positive flocks.
  • During 2023, a total of 484 animal feed material were tested for the presence of Salmonella. None of the animal feed material tested positive for Salmonella.

Trichinosis

  • In Ireland, there were no reported cases of trichinosis in 2023 (HPSC, 2024).
  • During 2023, a total of 3,314,318 tests carried out for Trichinella under objective sampling in horses (n=2,037) and pigs (n=3,312,281), with no positive samples detected.

Toxoplasmosis

In Ireland, there were 20 notified cases of toxoplasmosis in 2023, resulting in a CIR of 0.28 per 100,000 population (HPSC, 2024). This disease ranked eighth in terms of incidence compared to the other zoonoses evaluated.

  • During 2023, a total of 279 animal samples were tested under objective sampling for the presence of Toxoplasma. None of the samples obtained from goats (n=3) were positive. Fifty (18.1%) of the 276 samples obtained from sheep were positive for Toxoplasma.

Tuberculosis (TB)

  • In Ireland, there were 223 notified cases of tuberculosis in 2023, resulting in a CIR of 4.22 per 100,000 population (HPSC, 2024). This disease ranked fifth in terms of incidence compared to the other zoonoses evaluated. Globally, most cases of zoonotic TB are caused by M. bovis, and cattle are the major reservoir. At the time of publishing, the M. bovis human data was not available.
  • During 2023, a total of 107,621 bovine herds were tested for the presence of Mycobacterium, with 5,172 herds identified as infected. Furthermore, 104,373 herds herds were classified with the status of being officially free from the disease.
  • In addition to the bovine herds tested, a total of 1,301 objective animal samples and 127 suspect animal samples were tested for the presence of Mycobacterium. Of the objective samples 640 detections were observed. These included:
    • 562 (49.4%) of 1,137 of badgers.
    • 21 (67.7%) of 31 of goats.
    • 1 (12.5%) of 8 pigs.
    • 56 (45.9%) of 122 wild deer
      Of the suspect samples, 65 detections were observed. These included:
    • 62 (72.1%) of 86 alpacas.
    • 3 (8.3%) of 36 elephants.
      Variant Creutzfeldt-Jakob disease (vCJD), Bovine Spongiform Encephalopathy (BSE) and Transmissible Spongiform Encephalopathy (TSE)
  • In Ireland, there were no reported cases of vCJD in 2023. The last reported case of vCJD occurred in 2006 (HPSC, 2024). 

Verocytotoxigenic Escherichia coli (VTEC), also known as Shiga toxin-producing Escherichia coli (STEC)

  • In Ireland, there were 912 notified cases of VTEC in 2023, resulting in a CIR of 17.27 per 100,000 population (HPSC, 2024). This disease ranked second in terms of incidence compared to the other zoonoses evaluated.
  • During 2023, a total of 106 routine food samples (meat n=85; other foods n=21) and 42 suspect food samples (meat n=18; other foods n=24) were tested for the presence of VTEC/STEC. None of the samples tested were positive.

Yersiniosis 

  • In Ireland, there were 30 notified cases of yersiniosis in 2023, resulting in a CIR of 0.57 per 100,000 population (HPSC, 2024). This disease ranked seventh in terms of incidence compared to the other zoonoses evaluated.
  • During 2023, a total of 5,588 animal samples were tested under objective (n=5,584) and suspect (n=4) sampling for the presence of Yersinia. Yersinia was detected in 8 samples. These included:
    • 6 (0.2%) of 3,609 cattle.
    • 1 (100%) of 1 fox.
    • 1 (0.4%) of pig fattening herds.

References

European Food Safety Authority (EFSA), 2024. Manual for reporting on zoonoses and zoonotic agents, under Directive 2003/99/EC, and on some other pathogenic microbiological agents for information derived from the year 2023. Available here: https://efsa.onlinelibrary.wiley.com/doi/pdf/10.2903/sp.efsa.2023.EN-7825
European Food Safety Authority (EFSA) and European Centre for Disease Prevention and Control (ECDC), 2024. European Food Safety Authority and European Centre for Disease Prevention and Control. The European Union One Health 2023 Report. Available here: https://www.ecdc.europa.eu/en/publications-data/european-union-one-health-2023-zoonoses-report

Health Protection Surveillance Centre (HPSC), 2024. Health Protection Surveillance Centre. Infectious Disease Notifications in Ireland, 2019 - 2023. Available here: www.hpsc.ie/notifiablediseases/annualidstatistics