Herd-level diagnosis for Salmonella enterica subsp. enterica serovar Dublin infection in bovine dairy herds J. Veling a,* , H.W. Barkema a,1 , J. van der Schans a , F. van Zijderveld b , J. Verhoeff a a Animal Health Service, P.O. Box 9, 7400 AA Deventer, The Netherlands b Department of Bacteriology, Institute for Animal Science and Health, ID Lelystad, P.O. Box 65, 8200 AB Lelystad, The Netherlands Received 2 February 2001; accepted 5 November 2001 Abstract Herd-level sensitivities of bacteriological and serological methods were compared in 79 bovine dairy herds, recently infected with Salmonella enterica subsp. enterica serovar Dublin. All farms experienced clinical signs of salmonellosis for the ®rst time and had no history of vaccination against salmonellosis. At the start of the study, infection with serovar Dublin was con®rmed with at least one positivebacteriologiccultureforserovarDublinfromaclinicalcasegoldstandardforherdinfection). Bacteriological culture was done on samples of dung-pits, drinking water, bulk-milk ®lters, and faeces of animals with current or earlier clinical signs of salmonellosis. Blood samples of all animals and bulk-milk samples were tested using an ELISA. Herd-level sensitivity HSe) of culture of dung-pits, drinking water, bulk-milk ®lters, and faeces of animals with current or earlier signs of salmonellosis was 45, 5, 7, and 38%, respectively. HSe for serology of all animals was 100%. If blood samples of all calves 4±6 months old were examined, at least one calf was seropositive on 91% of the infected farms. If serology was performed on samples of animals with current or earlier signs of salmonellosis, at least one animal was seropositive on 80% of the infected farms. HSe for bulk-milk samples was 54%. However, if clinical signs of salmonellosis were observed only in lactating animals, sensitivity of bulk-milk serology was 79%. Interesting combinations of methods were the combination of serology of bulk milk with either serology of animals with current or earlier signs of salmonellosis HSe  91%, or serology of all calves of 4±6 months old HSe  99%. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Serovar Dublin; Cattle; Herd-level diagnosis; Culture; Serology; Herd-level sensitivity Preventive Veterinary Medicine 53 2002) 31±42 * Corresponding author. Tel.: 31-570-660-343; fax: 31-570-660-345. E-mail address: j.veling@gdvdieren.nl J. Veling). 1 Current address: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada C1A4P3. 0167-5877/02/$ ± see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0167-587701)00276-8