Environmental Contamination is a Major Contributor to Prevalence of Serpulina hyodysenteriae Infection of Swine on Farms Medicating Against Swine Dysentery

University of Nebraska 1995 Swine Day Report. Swine dysentery is a highly contagious diarrheal disease of growing and finishing swine causing estimated losses of more than $2.4 million monthly to Iowa pork producers. The spiral-shaped spirochete bacterium, Serpulina hyodysenteriae, is routinely identified by bacteriologic culture of intestinal specimens of swine affected with the disease. Specific differentiation of S. hyodysenteriae from other bacteria normally present in the intestines of swine is now possible with the use of a nucleic acid-based test developed by scientists in the Department of Veterinary & Biomedical Sciences at UN-L. The test can detect very low numbers of S. hyodysenteriae directly in the stools of swine by a process known as polymerase chain reaction (PCR). We are investigating alternative ways to reduce the economic losses due to swine dysentery. Serpulina hyodysenteriae is known to occur outside the pig; however, it is not clear how this affects persistence of the disease on swine farms. Also, house mice (Mus musculus) have been shown to be involved in the spread of S. hyodysenteriae on farms with swine dysentery, but the spirochete bacterium of mice has not been conclusively identified as S. hyodysenteriae. Developing more effective control strategies for swine dysentery requires a more complete understanding of the factors involved in persistence of the spirochete bacterium in pigs and in habitats other than its natural host. Serpulina hyodysenteriae strains belong to a species of bacteria with many shared characteristics; however, it is possible to distinguish variants within the species using specialized methods. One of these methods uses enzymatic digestion of deoxyribonucleic acid (DNA) obtained from closely related bacterial strains to compare them to each other. This method takes advantage of small differences in the DNA of individual strains to produce patterns of DNA banding or DNA fingerprint after separation of the DNA fragments by gel electrophoresis. DNA fingerprinting has become a method of choice for studies aimed at comparing organisms taken from different backgrounds and understanding the spread of disease-causing bacteria. The objectives of this work were: (i) Determine the relationship between persistence of S. hyodysenteriae on farms with swine dysentery and the presence of S. hyodysenteriae in pigs, the environment, and house mice on the same farm; and (ii) confirm the presence of S. hyodysenteriae outside of its natural host using the PCR test.