Setaria tundra, an emerging parasite of reindeer, and an outbreak it caused in Finland in 2003-2006

• Main Author: Laaksonen, Sauli
• Other Authors: Hård af Segerstad, Carl, University of Helsinki, Faculty of Veterinary Medicine, Finnish Food Safety Authority Evira, Fish and Wildlife Health Research Unit, Helsingin yliopisto, eläinlääketieteellinen tiedekunta, Helsingfors universitet, veterinärmedicinska fakulteten, Sukura, Antti, Oksanen, Antti
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Helsingin yliopisto 2010
• Subjects: eläinlääketiede; Tundra; Lapland
• Online Access: http://hdl.handle.net/10138/18996

Recent Finnish studies have revealed an array of filarioid nematodes and associated diseases that appear to be emerging in northern ungulates. All filarioid species produce microfilariae that are present in the host blood, and known vectors are haematophagous arthropods. Infections attributable to a species of the genus Setaria appear to have emerged in Scandinavian reindeer in 1973. The infections were associated with an outbreak of peritonitis. In the same year, tens of thousands of reindeer died in the northern part of the reindeer herding area of Finland. Severe peritonitis and large numbers of Setaria sp. worms were common findings. However, the prevalence of Setaria sp. in Scandinavian reindeer subsequently diminished. In Finland, the latest outbreak of peritonitis in reindeer started in 2003 in the southern and middle parts of the reindeer herding area. The proportion of reindeer viscera condemned due to parasitic lesions identified during meat inspections increased dramatically. These increases caused substantial economic losses and increased the workload associated with meat processing. The focus of the outbreak moved northward by approximately 100 km/yr, and by 2005 only the reindeer in Upper Lapland were free of lesions. During the same period, the peritonitis outbreak was apparently fading away in the southern area. The causative, agent based on morphological and molecular data, was identified as Setaria tundra. Reindeer calves with heavy infections of S. tundra expressed decreased thriftiness, poor body condition, and an undeveloped winter coat. Meat/post mortem inspection of diseased reindeer carcasses revealed ascites fluid, green fibrin deposits, adhesions, and live and dead S. tundra nematodes. Histopathology indicated granulomatous peritonitis with lymphoplasmacytic and eosinophilic infiltration. No specific bacterial growth was found. No significant impact on pH values of meat or on the organoleptic evaluation of meat was found. There was a significant positive correlation between worm counts ...