EFFECT OF HUSBANDRY METHODS ON SEROPOSITIVITY TO AFRICAN SWINE FEVER VIRUS IN SARDINIAN SWINE HERDS

Multiple logistic regression was used on serological data collected in the context of the Sardinian African swine fever (ASF) eradication pr ogram from pig farms in the province of Nuoro, Sardinia, The monthly p ercentage of ASFV-positive herds decreased significantly from October 1994 through March 1996 (P < 0.001). The farm-level risk of seropositi vity to African swine fever virus (ASFV) was higher in free-range farm s than in partial-confinement farms (odds ratios (OR) varied between 4 .9 in October 1994, and 5.7 in March 1996, P < 0.001). The risk of inf ection for total-confinement farms was one-fifth of the risk for parti al-confinement farms in October 1994 (OR = 0.2, P < 0.001), whereas in March 1996, the estimated OR was 0.57 and not significant (upper conf idence limit = 1.1). The maintenance of ASFV in Sardinia was primarily associated with free-range pig farms. The natural logarithm of the nu mber of pigs tested per visit in a farm was positively associated with the risk of herd seropositivity (OR = 2.6, P < 0.001). (C) 1997 Elsev ier Science B.V.