Sero-prevalence of subclinical paratuberculosis (Johne's disease) in dairy farms of Tehran-Iran using absorbed ELISA assay

Mycobacterium avium subspecies paratuberculosis causes Johne's disease in ruminants and have been also isolated from humans. Accurate statistical information about the disease prevalence in different regions of Iran is not available. The objective of the present study was to evaluate the prevalence of subclinical Johne's disease in dairy cattle herds of Tehran province, Iran. Knowing the disease prevalence and its damages could have an important role to manage the disease in the farms involved. In the present study which was conducted in the years 1391 to 1393, 338 serum and fecal samples from cows older than 18 months, were obtained from 14 dairy farms in Tehran province, Iran. Antibodies against Johne's disease were assayed using PARACHEK2 absorbed ELISA kit (ParaCheck, Prionics AG, Zurich, Switzerland). Fecal culture and Nested-PCR assays were performed to confirm the disease. The prevalence of the disease determined by ELISA and culture were 9.5% (95% CI: 6.66 - 13.23) and 3.6% (95% CI: 1.69 - 7.27), respectively. Furthermore, the herd prevalence of the disease was calculated using culture as 28.6% (95% CI: 9.58- 57.99) and ELISA as 57.14% (95% CI: 29.65- 81.19). To evaluate the diagnostic value of the test, ELISA results were compared to bacterial fecal culture as the gold standard test. According to the obtained results, ELISA can be considered as a suitable screening test for the diagnosis of paratuberculosis due to the convenient sampling, high speed and low price. It is suggested that precise control programs to be performed based on the prevalence of the disease in Tehran province.