Lewerin et al. Acta Veterinaria Scandinavica 2010, 52:7 http://www.actavetscand.com/content/52/1/7 C A S E R E P O R T Open Access Anthrax outbreak in a Swedish beef cattle herd - 1st case in 27 years: Case report Susanna Sternberg Lewerin1*, Marianne Elvander1, Therese Westermark2, Lisbeth Nisu Hartzell3, Agneta Karlsson Norström4, Sara Ehrs5, Rickard Knutsson5, Stina Englund6, Ann-Christin Andersson7, Malin Granberg7, Stina Bäckman7, Per Wikström7, Karin Sandstedt5 Abstract After 27 years with no detected cases, an outbreak of anthrax occurred in a beef cattle herd in the south of Swe- den. The outbreak was unusual as it occurred in winter, in animals not exposed to meat-and-bone meal, in a non- endemic country. The affected herd consisted of 90 animals, including calves and young stock. The animals were kept in a barn on deep straw bedding and fed only roughage. Seven animals died during 10 days, with no typical previous clinical signs except fever. The carcasses were reportedly normal in appearance, particularly as regards rigor mortis, bleed- ing and coagulation of the blood. Subsequently, three more animals died and anthrax was suspected at necropsy and confirmed by culture and PCR on blood samples. The isolated strain was susceptible to tetracycline, ciprofloxacin and ampicillin. Subtyping by MLVA showed the strain to cluster with isolates in the A lineage of Bacillus anthracis. Environmental samples from the holding were all negative except for two soil samples taken from a spot where infected carcasses had been kept until they were picked up for transport. The most likely source of the infection was concluded to be contaminated roughage, although this could not be substantiated by laboratory analysis. The suspected feed was mixed with soil and dust and originated from fields where flooding occurred the previous year, followed by a dry summer with a very low water level in the river allowing for the harvesting on soil usually not exposed. In the early 1900s, animal carcasses are said to have been dumped in this river during anthrax outbreaks and it is most likely that some anthrax spores could remain in the area. The case indicates that untypical cases in non-endemic areas may be missed to a larger extent than previously thought. Field tests allowing a preliminary risk assessment of animal carcasses would be helpful for increased sensi- tivity of detection and prevention of further exposure to the causative agent. Background Anthrax is a bacterial infection that affects both animals and humans. It is caused by the gram positive, rod- shaped spore-forming bacterium Bacillus anthracis. Fully virulent isolates contain two plasmids, pX01 and pX02. The former encodes the tripartite protein exo- toxin complex, consisting of lethal factor, protective antigen and oedema factor, and the latter encodes the poly-D-glutamic acid capsule [1,2]. In an environment with elevated CO2 levels, as in an infected animal, the * Correspondence: susanna.lewerin@sva.se 1Department of Disease control & Epidemiology, National Veterinary Institute, SE-751 89 Uppsala, Sweden virulence factors are induced and sporulation is inhib- ited [1]. When the bacteria are released outside the infected host, as when blood oozes from a carcass, the lower CO2 levels in open air induce sporulation, which allows the organism to survive in the environment for long periods of time [1]. The spores are extraordinarily resistant to extremes of pH, heat and cold, desiccation and various chemical agents [3,4]. The period of survival of anthrax spores in the environment can be very long [5,6], reportedly up to 200 years [7], and is affected by pH, water activity, temperature and the presence of nutrients. © 2010 Lewerin et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.