Risk factors for clinical salmonellosis in Virginia, USA cattle herds

Veterinarians working in several Virginia, USA counties noticed an increase in clinical salmonellosis in cattle herds during 1994. We conducted a case -control study to identify potential risk factors for salmonellosis in catt le herds in this region. The potential impact of exposure to poultry-relate d factors was of particular interest because of the close proximity of poul try and cattle operations in this part of the state. Information was collec ted from 23 case farms and 23 control farms matched by herd veterinarian, t ype of enterprise (beef vs. dairy), and location. Fecal and environmental s amples were collected during herd visits for bacteriologic culture. Salmonella was isolated from 4.7% of 531 fecal, feed, water, and environmen tal samples collected. Salmonella Typhimurium was the serotype found most f requently in clinical cases in participating herds and from samples collect ed during study visits. Case herds had a higher percentage of study samples positive for Salmonella. Potential risk factors were screened using method s for pair-matched data and then analyzed in individual conditional logisti c-regression models to estimate odds ratios with 95% profile likelihood con fidence intervals. Significant factors included: the number of mature cows in the herd (OR = 1.01; CI 1.00, 1.03), percent change in the number of mat ure cows during 1994 (OR = 0.68; CI 0.11, 0.96), having calves usually born in a building rather than outdoors (OR = 0.17; CI 0.01, 0.98), poultry man ure spread on bordering property (OR = 4.00; CI 1.00, 26.50), signs of rode nts in cattle-housing or feed-storage areas (OR = 2.75; CI 0.94, 9.92), and contact of wild,geese with cattle or feed (OR = 4.5; 1.16, 29.51). (C) 200 1 Elsevier Science B.V. All rights reserved.