Yersinia enterocolitica is a bacterium that causes yersiniosis, an intestinal infection that affects both children and adults. It is part of the genus Yersinia, which also includes the organisms responsible for plague (Yersinia pestis) and other gastrointestinal diseases. Unlike some related bacteria, Y. enterocolitica primarily spreads through contaminated food, especially undercooked pork, unpasteurised milk, or untreated water (Riahi et al., 2021).

Once ingested, this bacterium can invade the intestinal lining and spread to lymph nodes in the abdomen, sometimes mimicking appendicitis. In children, it is a common cause of diarrhoeal illness, while in adults, it can trigger abdominal pain, fever, and in some cases, post-infectious complications such as reactive arthritis (Mafokwane et al., 2023).

✔️ Causes yersiniosis, a gastrointestinal infection

✔️ Commonly spreads through contaminated food (especially undercooked pork), unpasteurised milk, or untreated water

✔️ Can grow at refrigerator temperatures, making it a persistent food safety concern

✔️ Symptoms include diarrhoea, abdominal pain, fever, and vomiting

✔️ In children, it may mimic appendicitis due to swollen abdominal lymph nodes

✔️ Some strains produce a heat-stable enterotoxin that contributes to diarrhoea

✔️ Possible complications include reactive arthritis and, rarely, bloodstream infections

✔️ More common in young children and people with weakened immune systems

✔️ Infection is often self-limiting, but severe cases may require antibiotics

When Yersinia enterocolitica gets into the body—usually through contaminated food or water—it first meets the body’s early defences (the innate immune system). The cells lining the gut quickly sense the bacteria and release chemical “alarm signals” that call in white blood cells like neutrophils and macrophages to fight the infection. These cells try to eat and destroy the bacteria, but Yersinia has tricks to survive. It produces special proteins (called Yops) that can block the body’s defence cells and slow down the immune response.

If the bacteria get past this first line of defence, the second wave of immunity (the adaptive immune system) is activated. Special cells called dendritic cells carry pieces of the bacteria to the immune “command centre,” where T cells and B cells are activated. T cells help organise the attack and can kill infected cells, while B cells make antibodies. In the gut, IgA antibodies block Yersinia from sticking to the lining, and in the blood, IgG antibodies help stop the bacteria from spreading.

Most people recover with just mild gut symptoms, but sometimes the immune system’s strong reaction can backfire. In a few people, the infection can lead to reactive arthritis, where the immune system accidentally attacks the joints because it confuses the body’s tissues with the bacteria.

Unhealthy levels of Yersinia enterocolitica can cause a wide range of gut-related and systemic symptoms. In the digestive system, people often experience acute diarrhoea, abdominal cramps, fever, and vomiting. Some individuals may develop bloody stools or prolonged diarrhoea that lasts for several weeks. In children, symptoms may mimic appendicitis, with right-sided abdominal pain and fever. Severe dehydration can occur if fluid loss is not managed (Mafokwane et al., 2023; Riahi et al., 2021).

Beyond the gut, Y. enterocolitica can sometimes spread or trigger complications. In vulnerable groups, such as children, older adults, or people with weakened immunity, it may lead to bloodstream infections, joint pain (reactive arthritis), or long-term inflammation in the gut. Chronic conditions like irritable bowel syndrome (IBS) have also been linked to past infections. Because of these risks, persistent or severe symptoms should not be ignored and may require medical attention (Mafokwane et al., 2023; Riahi et al., 2021).

Yersinia enterocolitica is recognised as a foodborne pathogen that can affect gut health in South Africa, although it is often overlooked compared to other bacterial infections.

Presence in South Africa

Studies in Africa, including South Africa, have detected Y. enterocolitica in both humans and animals. In one investigation of diarrhoeal disease among children, cases linked to this bacterium were reported in stool samples (Riahi et al., 2021). The bacterium has also been found in contaminated pork products, which are a major source of infection worldwide. Since pork and dairy are commonly consumed in South Africa, these foods can serve as transmission pathways if not handled or cooked properly (Riahi et al., 2021).

Impact on Gut Health

When Y. enterocolitica infects the gut, it can lead to inflammation and disturbances in the intestinal lining, resulting in diarrhoea, abdominal pain, and in some cases longer-lasting complications like reactive arthritis (Riahi et al., 2021). For South Africans, particularly children, this can add to the overall burden of diarrhoeal diseases, which are already a public health challenge. The infection is often underdiagnosed, meaning its impact on gut health may be greater than currently recognised.

Supporting the body’s defences against Yersinia enterocolitica starts with building a strong immune system and a resilient gut. A balanced diet rich in whole foods, quality sleep, and stress management are essential foundations for immunity. Adding probiotics and fibre-rich foods supports beneficial gut bacteria, which form a natural barrier against harmful microbes. Staying hydrated also helps maintain gut health and flushes out toxins.

Equally important is food safety, since Y. enterocolitica often spreads through undercooked pork and unpasteurised dairy. Cooking meat thoroughly, avoiding unpasteurised products, and preventing cross-contamination in the kitchen can greatly reduce risk. Regular handwashing after handling raw meat further strengthens this protective layer. Together, these immune-supporting habits and food safety measures not only help prevent infection but also reduce the severity of illness if exposure occurs.