Health status in regard to Johne's disease is a major concern in the selection of bull calves to be used at semen collection centers. This has been emphasized by the EFSA (2004), which recommended that only Mycobacterium avium subsp. paratuberculosis (MAP) negative cows from herds with low prevalence should provide calves for reproduction.

A program based on annual MAP screening and differential intervention strategies, depending on the seroprevalence detected was developed by the Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe) in 2005. Twenty-three dairy cattle herds (average no. heads = 77; min = 33, max = 173) located in Trentino region, Italy, that regularly provide bull calves to the same reproduction center were enrolled. All the cows older than 24 months were annually subjected to the Elisa Pourquier ® screening test. Confirmation of positive or doubtful results was carried out by fecal culture and IS900 PCR tests. In 2005, 15 herds resulted negative, 5 had only a few seropositive results that were not confirmed by PCR or fecal culture, and 3 were infected with seroprevalence of 2.1%, 5.1% and 6.4% respectively. Clinical cases were described only in the two latter farms.

Based on these results, three mid-term (five-year) programs were developed in order to certify herd health status, eliminate the disease in low-prevalence herds, and reduce the seroprevalence in highly infected herds to under 5%.

In 2006, six previously negative herds tested positive by ELISA assay with the detection of Singleton reactors in all cases but one in which the infection was confirmed by fecal culture.

On the basis of the results of the screening program, the local dairy producers' association and the IZSVe organized meetings to inform the farmers and the practitioners of the risk factors behind the spread of paratuberculosis and the control measures to be taken in infected herds. A more-detailed evaluation of the risk of disease introduction in negative herds and the biocontainment measures implemented in infected premises was performed by "in farm" inspections and a questionnaire-based survey. The questionnaire used was derived from one developed by the National Johne's Working Group, US. The farmers were asked to provide information on the management of each production phase, restocking rates, production, and the movement of animals. On the basis of the health status and information collected by the inspection and the survey, a set of biosecurity and biocontainment measures tailored to individual farms was agreed between farmers and veterinarians.