Paratuberculosis is an enteric disease of ruminants caused by Mycobacterium avium subsp. paratuberculosis(Map) with a high economic impact in cattle breeding. The trasmission of the infection to susceptible animals is mainly considered to occur via the fecal-oral route. Contaminated colostrum or milk are important means of infection.

In this study, the effects of a control program for paratuberculosis have been assessed during a six years period (2001-2006). The survey involved 8 dairy herds located in Northern Italy, with a number of animal >24 months ranging from 224 to 784, mean 437 (SD = 154), median 411. Globally, a mean of 3497 (SD = 328) animals >24 months per year were monitored during the six years period. Seropositivity rate and prevalence of clinical paratuberculosis per year have been detected in each herd involved in the study.

In the control program protocol, few modifications of the original management practices were made. In particular, cows showing diarrhea were readily detected, isolated and culled after paratuberculosis diagnosis confirmation by laboratory investigations. Cows were tested by serum ELISA for Map antibodies during the dry period. Calves were fed only with colostrum from seronegative cows and with milk submitted to termical treatment (70°C for 40 min).

Considering the total number of animals >24 months from all the herds, history means (from 1995 to 2000) of the prevalences of seropositivity and clinical cases were 12.6% and 5.5%, respectively. Statistical analysis of seropositivity and clinical cases trends after the beginning of the control program showed a significant (p<0.01) reduction of both parameters during the six years period. In particular, the prevalence of seropositivity decreased from 12.7% to 7,3% and clinical cases decreased from 5.3% to 3.2%.

As side effects following the application of the pasteurizers, a strong reduction of neonatal diarrhea has been observed in all the herds. In addition, the calf's mean weight gain/day moves from 500 g to 900 g. Conversely, an increase of myodystrophy cases has been detected after two months of age. The problem was solved by adding selenium and vitamin E to the pasteurized milk.