Lack of investment in swine enteric diseases

We have known about the causative bacteria that starts ileitis – Lawsonia intracellularis – for 40 years now. We then first cultured these bacteria that cause the disease some 20 years ago. However, knowledge about the actual pathogenesis is still lacking. Lawsonia is one of the very bacteria on the planet that cause a adenoma type thickening of epithelial cells in animals. It is strange that after so many years there is lack of direction of how these bugs actually cause this economically important disease. I think the reason why this unique mode of action is still such a mystery is the under-funding of research projects regarding these diseases. The simple question – how do these bugs make the pigs sick? – seems not a very popular project theme for national research foundations and councils and also companies to invest their money.

 

The same problem occurs for research regarding swine dysentery. Swine dysentery (SD) is caused by the spirochaetal bacterium Brachyspira hyodysenteriae. This organism causes a severe inflammation of the large intestine with bloody mucous diarrhoea (i.e. dysentery). Disease is common in pigs from 40 to 75 kg but severe cases occur occasionally in breeding pigs. There is no useful vaccine for swine dysentery and related to this, we still don’t know what is the actual pathogenesis, such as possible toxins involved in this disease. What I see is that the disease is a worldwide problem and seems to be re-emerging in the European Union and the US. This is partly because of the decisions to ban drugs like metridonazole and carbadox for pigs. These drugs were very effective when used in the past, but are now not available for use in most of the world.

 

While we wait and agitate for good research funding to gain more knowledge about the diseases and primarily their pathogenesis, in the meantime there are several other things a farmer can do. Management and nutrition wise there is a lot to gain to prevent or limit an outbreak of ileitis and swine dysentery, that is to focus on improving the overall gut health at weaning. Piglets between three and four weeks are experiencing a lot of gut and diet changes. It is likely that enteric conditions after weaning, like ileitis and dysentery can be prevented when piglets have less problems with coccidiosis and rotavirus around weaning.

 

Advancements in molecular research such as the genetic sequencing of the entire Lawsonia and Brachyspira genomes have provided good information on metabolic pathways. Also research has enabled methods for understanding the epidemiology of ileitis. But we still need new technology to find an effective solution against important enteric diseases. At the IPVS, my aim is to get some buzz going and refresh the discussion on enteric diseases. Hopefully we can initiate some new research funding programmes in the near future that will help us developing new solutions for swine dysentery and ileitis.”