1.2 What’s in a name?

The names used to describe this important disease vary around the world. Porcine intestinal adenomatosis (PIA) and proliferative haemorrhagic enteropathy (PHE) are often used terms alongside “Ileitis” and “garden hose gut”. Occasionally other names such as “hosepipe gut”, “slab-side” or “stone” pigs are used in some places. The name “proliferative enteropathy” was settled on to most accurately describe the basic lesion visible in all pigs with the disease. This name became more settled around 1993, at this time it was found that the single organism, the bacterium Lawsonia intracellularis, is responsible for all different clinical and pathological forms of proliferative enteropathy, including the common chronic and acute forms of the disease (McOrist et al. 1993). This organism is usually excreted via the faeces of infected animals and passed on when those faeces contact the snout of the next animal, so-called faecal-oral transmission. The various types of proliferative enteropathy disease that are seen, are the result of changes in infectious dose, age of the animal, and secondary inflammatory reac­tions by different animals. In many parts of the world, the term “Ileitis” is retained as a short, easy-to-say word for the disease and will mainly be used during this text.