Paratuberculosis has been described as one of the most important diseases affecting cattle worldwide. Studies conducted in various areas of Italy have indicated a high prevalence of paratuberculosis in dairy cattle. A study was carried out on Mycobacterium avium subsp. paratuberculosis (Map) infected dairy herds located in Northern Italy, namely in the Parma, Modena, and Reggio Emilia provinces. The aim was to identify management and environmental risk factors associated with three variables: Map seroprevalence (ELISA Herd Check IDEXX), incidence of clinical disease, and animal age of disease onset. The three variables were monitored over a 3-year period (2002-2004). The considered risk factors were: number of cows/herd , purchase of animals, scrape barn lactating cows, manure spread on fields, feed grown where manure was spread, calving assistance, wash udder, calves fed with farm/herd milk, each calf housed separately, iron content of drinking water.The herds were n=56, average number cows/herd 199 ± 204, median 116. The values (mean ± s.d.) of the considered variables were: seroprevalence 5.7 ± 3.4 (min 1.2, max 21.0), incidence 4.0 ± 1.9 (min. 1.2, max 8.4), animal age of disease onset in months 37.1 ± 2.7 (min. 31.0, max 42.5).The seroprevalence was associated (t-test) with number of cows/herd (p=0.027, correlation 0.2954), purchase of animals (p=0.004, correlation -0.3786), iron content of drinking water (p<0.001, correlation 0.4827). The incidence of disease was associated with the iron content of drinking water (p<0.001, correlation 0.7512). The age of disease onset was negatively associated with the number of cows/herd (p=0.019, correlation -0.3120) and with the iron content of drinking water (p<0.001, correlation -0.5803).