No difference in paratuberculosis seroprevalence between organic and conventional dairy herds in the Netherlands

Purpose. Paratuberculosis or Johne’s disease in cattle is considered to play a role in the pathogenesis of Crohn’s disease in humans. Whether organic production may influence the prevalence of paratuberculosis in dairy herds was not known until now and was therefore the purpose of our study. Methods. Blood samples were taken in 2003 from cows older than three years, originating from 76 organic dairy herds. Samples were tested for antibodies against Mycobacterium paratuberculosis using an ELISA. Data were compared with a similar analysis performed by the Animal Health Service on 579 dairy farms participating in the National Dutch Paratuberculosis Program, which includes a few organic herds. Results. The mean number of animals tested was 48 and 56 for the organic versus the control group, respectively. Of the 3688 organic sera tested, 43 revealed the presence of M. paratuberculosis antibodies. These seropositive animals originated from 22 farms (28.9 %). Fourteen farms (18.4 %) only had one seropositive animal. Two farms had 6 seropositive animals. In the control group 197 farms had seropositive animals (34 %), which was not statistically significant from the organic farms. In the control group 107 farms only had one seropositive animal (18.5 %), which was also not different as compared to the organic group. Conclusions. These data show that the incidence of Johne’s disease is not different between organic and regular dairy herds. The slightly higher incidence in the control group may be due to the fact that the number of animals tested per farm was larger. Grants: This study was supported by a grant (LNV program-PO-34) from the Dutch Ministry of Agriculture, Nature and Food Qualit