Eleni Michalopoulou

Descriptive epidemiology of the 2001 foot-and-mouth disease epidemic in Great Britain: the first five months

In February 2001, foot-and-mouth disease (FMD) was confirmed in Great Britain. A major epidemic developed, which peaked around 50 cases a day in late March, declining to under 10 a day by May. By mid-July, 1849 cases had been detected. The main control measures employed were livestock movement restrictions and the rapid slaughter of infected and exposed livestock. The first detected case was in south-east England; infection was traced to a farm in north-east England to which all other cases were linked. The epidemic was large as a result of a combination of events, including a delay in the diagnosis of the index case, the movement of infected sheep to market before FMD was first diagnosed, and the time of year. Virus was introduced at a time when there were many sheep movements around the country and weather conditions supported survival of the virus. The consequence was multiple, effectively primary, introductions of FMD virus into major sheep-keeping areas. Subsequent local spread from these introductions accounted for the majority of cases. The largest local epidemics were in areas with dense sheep populations and livestock dealers who were active during the key period. Most affected farms kept both sheep and cattle. At the time of writing the epidemic was still ongoing; however, this paper provides a basis for scientific discussion of the first five months.

Validating indicators of sheep welfare through a consensus of expert opinion

A consensus of expert opinion was used to provide both face and consensual validity to a list of potential indicators of sheep welfare. This approach was used as a first step in the identification of valid welfare indicators for sheep. The consensus methodology of the National Institute of Health, using pre-meeting consultation and focus group discussions, was used to ascertain the consensus opinion of a panel of sheep welfare experts. The Farm Animal Welfare Councils five freedoms were used as a framework to organise a list of current on-farm welfare issues for sheep. The five freedoms were also the welfare criterion used to identify potential on-farm welfare indicators for sheep. As a result, experts identified 193 welfare issues for sheep and lambs managed on farms across England and Wales. Subsequently, a combination of animal- (n = 26), resource- (n = 13) and management- (n = 22) based indicators was suggested for (i) adult rams, (ii) adult ewes (male and female sheep, over 1 year old), (iii) growing lambs (male and female sheep, over 6 weeks to 1 year old) and (iv) young lambs (male and female lambs, 6 weeks old and under). The results from this study could therefore be used to inform the further development of valid methods of assessing the on-farm welfare of sheep.

'Observing lame sheep: Evaluating test agreement between group-level and individual animal methods of assessment'

For on-farm sheep welfare assessment, a reliable, simple and robust method is required to assess the level of flock lameness. This study examined the level of test agreement for two binary lameness scoring systems for sheep. The first was a group-level lameness assessment of sheep performed on ungathered sheep at pasture and was termed group observation method (GOM). The second method of lameness assessment was performed after gathering of the sheep and involved close observation of the gait of individual sheep in a handling pen and was termed individual animal gait assessment (IAGA). Following individual gait assessment, each sheep was also examined for the presence of specific foot and limb lesions: white line lesions (WL); inter-digital dermatitis (ID); footrot (FR); contagious digital dermatitis (CODD); toe granuloma (TG); and joint swellings (JS). A total of 3,074 sheep were assessed from 40 flocks in North England and Wales by one assessor. Test agreement between the assessment methods was found to be good as judged by linear regression and Bland-Altman plots. The method of group observation identified a slightly higher proportion of lame sheep compared to the individual animal examination and also appeared to be a more feasible on-farm method of observation. Over half of the sample sheep were identified with WL but this did not appear to be associated with a high level of lameness (as assessed by IAGA) with just under 12% of sheep with WL being identified as lame. In contrast, the percentage of lame sheep was most closely associated with CODD and over 80% of animals with this lesion were scored as lame.

Inter-observer agreement for clinical examinations of foot lesions of sheep.

In sheep, the diagnosis of foot lesions is routinely based on physical examination of the hoof. Correct diagnosis is important for the effective treatment, prevention and control of both infectious and non-infectious causes of lameness. Therefore, the aim of this study was to evaluate the level of inter-observer agreement for clinical examination of ovine foot lesions. Eight observers of varying experience, training and occupation performed foot examinations on a total of 1158 sheep from 38 farms across North England and Wales. On each farm, a group of two to four observers independently examined a sample of 24 to 30 sheep to diagnose the presence or absence of specific foot lesions including white line lesions (WL), contagious ovine digital dermatitis (CODD), footrot (FR), inter-digital dermatitis (ID) and toe granuloma (TG). The inter-observer agreement of foot lesion assessments was examined using Fleiss kappa (κ), and Cohens κ examined the paired agreement between the test standard observer (TSO) and each observer. Scoring differences with the TSO were examined as the percentage of scoring errors and assessed for evidence of systematic scoring bias. With the exception of WL (maximum error rate 33.3%), few scoring differences with the TSO occurred (maximum error rate 3.3%). This suggests that observers can achieve good levels of reliability when diagnosing most of the commonly observed foot conditions associated with lameness in sheep.