Use of PCR to determine the pattern of shedding of Lawsonia intracellularis in swine and the frequency of infected farms in mexico

摘要

Porcine proliferative enteropathy or ileitis is a disease of pigs caused by Lawsonia intracellularis that produces mainly loss of weight. Recently the diagnosis in vivo has been simplified by the development of techniques based on the poiymerase chain reaction (PCR) that allow detection of the bacteria in faecal samples. In Mexico there have been reports on clinical observations of the disease but epidemiologiesl studies have not been carried out. The objectives of this work were: 1. To determine by PCR the pattern of shedding of L. intracellularis in an experimental model in pigs and 2. To establish the frequency of farms in Mexico where pigs infected with L. intracellularis are found. Experimental infection: A group of 16 one month old pigs froma L. intracellularis infected farm as determined by PCR were placed together with 16 one month old susceptible pigs. Every seven days faeces from 5 animals were obtained and clinical signs were recorded. The experiment had a duration of 63 days. Field study: A survey was done in 148 farrow-to-finish farms from different parts of the country. From each farm an average of 8 faecal samples from 4 to 20 week old animals were obtained and tested by PCR In addition a clinical survey was done in 35 infected and 27 non infected farms.