Seroprevalence of Dictyocaulus viviparus in first grazing season calves in Sweden Johan Ho ¨glund a, * , Sven Viring b , Mats To ¨rnqvist c a Department of Parasitology (SWEPAR), National Veterinary Institute and Swedish University of Agriculture Sciences, S-751 89 Uppsala, Sweden b Swedish Animal Health Service, National Veterinary Institute, S-750 07 Uppsala, Sweden c Swedish Animal Health Service, Box 505, S-244 82 Ka ¨vlinge, Sweden Received 1 March 2004; received in revised form 13 July 2004; accepted 25 July 2004 Abstract A serological survey was carried out to determine the prevalence and geographical distribution of Dictyocaulus viviparus in calves after their first grazing season in Sweden. A total of 754 animals from 76 randomly selected herds in seven geographical regions were examined between September 24 and December 19, 2001. To get an indication about the geographical distribution of the infection 41 herds with beef-suckler calves were investigated. On each farm, blood was collected from 8 to 10 animals after an average of 26  24 days post-housing to determine specific IgG 1 levels against a possible lungworm sperm antigen that is highly specific against patent infections of D. viviparus. We also investigated the seroprevalence of lungworm infection in relation to cattle management. In one region additional samples were analysed from 35 herds either with: (a) beef-suckling calves that were dewormed at housing, (b) untreated organically raised dairy calves, and finally from conventionally raised dairy calves either, (c) with or, (d) without a prophylactic anthelmintic treatment programme against gastrointestinal parasites on pasture. A questionnaire was used to obtain information about herd size and management, including measures to control nematode parasites on the farm. A total of 86 (11.8%) out of 754 animals had antibodies against D. viviparus, and at least one infected individual was detected in 30 (39.5%) of the 76 herds examined. Lungworm infected animals were found throughout the country and there was no significant differences between regions, although in southern and southwestern Sweden 70.0% of the herds were infected. Furthermore, there were no major differences in the seroprevalence in relation to management. Between 40.0 and 44.4% of the herds were infected irrespective of management, with the exception of calves from organic herds www.elsevier.com/locate/vetpar Veterinary Parasitology 125 (2004) 343–352 * Corresponding author. Tel.: +46 18 674156; fax: +46 18 309162. E-mail address: johan.hoglund@sva.se (J. Ho ¨glund). 0304-4017/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2004.07.018