Short Communication Evaluation of the impact and control of enzootic abortion of ewes David Longbottom a,⇑ , Gary Entrican a , Nicholas Wheelhouse a , Helen Brough b , Catherine Milne c a Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh EH26 0PZ, UK b Epidemiology Research Unit, SAC, Drummondhill, Stratherrick Road, Inverness IV2 4JZ, UK c SAC Edinburgh, Peter Wilson Building, Kings Buildings, West Mains Road, Edinburgh EH9 3JG, UK article info Article history: Accepted 13 June 2012 Available online xxxx Keywords: Chlamydia abortus Enzootic abortion of ewes Vaccination Disease control Farmer survey abstract Despite the availability of effective management and treatment strategies, Chlamydia abortus remains the single most frequently diagnosed cause of infectious ovine abortion (enzootic abortion of ewes, EAE) in the UK and one of the most significant causes of lamb mortality world-wide. In 2007, a survey of UK farm- ers, veterinarians and other farm animal holders was conducted to gather information on their percep- tions of the risk of acquiring infection and the management practices employed to control the disease. The survey indicated that the preferred options for controlling EAE are either through vaccination and/ or keeping flocks closed. However, further analysis of data indicates that implementation of these strat- egies does not provide a guarantee of exclusion of disease from flocks and thus further work is required to improve on current intervention strategies. Ó 2012 Elsevier Ltd. All rights reserved. Infectious ovine abortion is a major health problem in sheep world-wide, having significant financial and welfare implications. While several organisms are capable of causing infectious abortion in sheep, 1 the single most common cause in the UK is the bacterium Chlamydia abortus, the aetiological agent of enzootic abortion of ewes (EAE), also known as ovine enzootic abortion (OEA) (Longbot- tom and Coulter, 2003). In 2007, a survey of farmers, veterinarians and other veterinary workers was conducted to determine the management strategies used for controlling EAE, their understanding of control options and perceived risks for acquiring infection. A convenience sam- pling method was used to achieve good coverage throughout the UK. Questionnaires (see Appendix A: Supplementary material) were distributed through the Moredun Foundation, which has an extensive UK-wide membership network, as well as through Qual- ity Meat Scotland and at all major UK agricultural shows. The survey response rate was 22% (442/2000 questionnaires re- turned); the results are summarised in Table 1. Among respon- dents, 33.8% reported cases of EAE (28% in Scotland, 37% in England, 38% in Wales and 70% in Northern Ireland). This is similar to the figures published by DEFRA for diagnosed cases of ovine fetopathy 2 and therefore the responses are considered to offer a good representation of the EAE situation in the UK. Lowground and upland farms had a higher prevalence (40.7%) than hill (16.7%) or pedigree farms (8.6%). Lowground, upland and hill flocks are differentiated by land type and have different systems of flock man- agement; lowground flocks typically have higher sheep–sheep con- tact levels than upland flocks and much higher contact levels than hill flocks. The prevalence of EAE was significantly lower in flocks of <150 animals (9.4%) than in larger flocks (47.6%). Due to the ‘silent’ or latent nature of infection, where the organ- ism lies dormant in non-pregnant ewes until a subsequent preg- nancy (Longbottom and Coulter, 2003), introduction of infected replacement animals is one of the main routes of transmission. This was recognised by 55.8% of respondents, who believed that replacements were the major source of disease. This risk can be minimised by maintaining a closed flock or through the purchase of EAE-free accredited animals, such as those within UK health schemes. 3,4 Most respondents (63.6%) indicated that they had closed flocks, 22% bought from non-accredited sources and 14.4% reported that they always or sometimes purchase EAE accredited replacements. Respondents that had experienced EAE were more likely to pur- chase replacements from non-accredited sources (32.4%) than those that had not experienced the disease (16.6%). Other sug- gested sources of infection included replacement rams, wildlife sources, feral sheep, dogs or groundwater, for which there is some evidence of a role in the spread of EAE (Appleyard et al., 1985; Mainar-Jaime et al., 1998; Lemus et al., 2010). Other approaches to disease control include the use of diagnos- tic screening, antibiotics and vaccination. Diagnostic screening is a way of monitoring the EAE status of a flock to identify infected 1090-0233/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.tvjl.2012.06.018 ⇑ Corresponding author. Tel.: +44 131 4455111. E-mail address: david.longbottom@moredun.ac.uk (D. Longbottom). 1 See: http://www.vla.defra.gov.uk/reports/rep_vida.htm. 2 See: http://www.vla.defra.gov.uk/reports/docs/rep_vida_sheep00_07.pdf. 3 See: http://www.sac.ac.uk/consulting/services/i-r/sghs/. 4 See: http://www.hisha.org.uk. The Veterinary Journal xxx (2012) xxx–xxx Contents lists available at SciVerse ScienceDirect The Veterinary Journal journal homepage: www.elsevier.com/locate/tvjl Please cite this article in press as: Longbottom, D., et al. Evaluation of the impact and control of enzootic abortion of ewes. The Veterinary Journal (2012), http://dx.doi.org/10.1016/j.tvjl.2012.06.018