Yersiniosis

Yersiniosis is an infectious disease of the gastrointestinal tract caused by bacteria of the genus Yersinia other than Y. pestis, with the great majority of human cases attributed to Y. enterocolitica and a small minority to Y. pseudotuberculosis ^[2]. The causative organisms are zoonotic pathogens that can dwell in livestock, wild animals, pets, fish, and rodents, which may act as asymptomatic carriers excreting the bacteria in faeces ^[1][2].

Infection with Y. enterocolitica produces a range of symptoms that vary with the age of the affected person; children under five years tend to experience more severe symptoms ^[2]. Common manifestations include fever, abdominal pain, and diarrhoea, with older children and adults frequently presenting with right-sided abdominal pain and fever that can mimic appendicitis ^[2]. Although illness is typically self-limiting, complications such as bowel perforation, toxic megacolon, peritonitis, bacteraemia, erythema nodosum, joint pain, and sepsis can occur, particularly in young children, the elderly, and immunocompromised patients ^[2].

Yersiniosis is a globally distributed foodborne zoonosis, and WHO estimates indicate that hundreds of millions of foodborne illness cases occur annually, with bacterial pathogens including Y. enterocolitica contributing substantially to this burden ^[1]. In New Zealand, yersiniosis notification rates are high relative to other developed countries and have been increasing, with over 99% of human cases attributed to Y. enterocolitica; a shift in the predominant strain from biotype 4 to biotype 2/3 serotype O:9 has been observed since around 2012 ^[3]. Most cases are considered sporadic without an identifiable source, although a large outbreak of 220 cases caused by Y. pseudotuberculosis was recorded in New Zealand in 2014 ^[3]. Waterborne outbreaks have also been described, particularly where drinking water is sourced from ground or rainwater subject to animal or bird contamination ^[2].

Y. enterocolitica is most likely transmitted through the foodborne route, with documented associations with the consumption of undercooked pork products, unpasteurised milk, and contaminated water, as well as with the handling of raw chitterlings ^[3][2]. Asymptomatic animal carriers shed the organism in faeces, contaminating the environment, food production areas, and fresh produce, and pathogens may also persist in biofilms on equipment surfaces ^[1]. Contaminated water supplies, particularly unregulated ground or rainwater sources in rural settings, represent an additional transmission pathway ^[2].

Because transmission is predominantly foodborne and zoonotic, prevention depends on a One Health approach that addresses animal reservoirs, food production environments, and water sources ^[3]. Whole-genome sequencing is being applied to improve epidemiological investigation and to clarify transmission pathways, supporting more targeted interventions ^[3]. Improved isolation methods for detecting Yersinia spp. in foods and the application of genomic typing are expected to strengthen evidence-based prevention strategies ^[3].

1. 1 Chlebicz A et al. Campylobacteriosis, Salmonellosis, Yersiniosis, and Listeriosis as Zoonotic Foodborne Diseases: A Review. Int J Environ Res Public Health. 2018 Apr 26. PMID: 29701663. doi: 10.3390/ijerph15050863. PubMed: https://pubmed.ncbi.nlm.nih.gov/29701663/
2. 2 Wikipedia contributors. Yersiniosis - Wikipedia [Internet]. Wikipedia. cited 4 Sept 2026. Available from: https://en.wikipedia.org/wiki/Yersiniosis
3. 3 Rivas L et al. Yersiniosis in New Zealand. Pathogens. 2021 Feb 10. PMID: 33578727. doi: 10.3390/pathogens10020191. PubMed: https://pubmed.ncbi.nlm.nih.gov/33578727/