Patients, methods, and results

Questionnaires were sent to 292 patients at this practice who worked with sheep and were aged between 16 and 65 on 1 January 1995. The results from 251 questionnaires were analysed (effective response rate 86%). Table 1 shows the high exposure to and recognition of orf in sheep. Nearly all respondents claimed to be able to recognise human orf. Almost a third (73) reported having had it, with over a third reporting previous infection in a household member. Of the 73 reported cases, 34 (47%) were in women and 39 (53%) in men. Over a fifth reported two or more attacks, the second attack mostly occurring within two years. Most respondents had had their first attack in their teenage or early adult life, which is in keeping with starting work on the family farm. Most cases (60/73 (82%)) occurred in spring or summer. In addition, I identified 58 separate episodes of orf infection from general practice records. Thirty four (59%) occurred in April, May, and June—19 (33%) in May alone (table 1).

Sixteen respondents (22%) reported an accompanying red blotchy rash; erythema multiforme, toxic erythema, or allergic reaction was recorded in the general practice notes in nine cases (12%). Eight respondents (11%) indicated that they had blisters on their arms, body, face, or mouth when they had had orf. Widespread vesicular eruption was confirmed from the records in only three cases (4%). All of these had preceding erythema multiforme. Of the 24 people (33%) whose work was affected, four reported problems for less than a week, 11 for one to two weeks, and nine for more than two weeks. Eleven patients (15%) had time off work: three for less than one week, three for one to two weeks, and five for more than two weeks.

Comment

Orf is common in flocks in mid-Wales. Most people who work with sheep can recognise both animal and human infection, but self diagnosis and lack of effective treatment could explain why almost a quarter of patients with orf chose not to consult a doctor. One episode of orf may3 or may not4 confer life long immunity. Although a fifth of my respondents reported two or more attacks, infection declined with increasing age. The seasonal variation correlated with the end of the lambing season.

The mechanism of the papulovesicular eruption is not understood, but such a dramatic rash is unlikely to be ignored by both patient and doctor. The hands are most commonly infected (occasionally the face), which explains why patients' jobs are affected and they lose time at work. Most attacks occur at the busiest time of the farming year, and illness is clinically significant. As there is no effective treatment, further evaluation of simple preventive measures such as wearing gloves and isolation of infected sheep needs to be carried out, although costs and practical considerations may prove difficult to overcome.

I thank Jane Jones of Rhayader Surgery for her help in completing this study, Trish Buchan for her help with the questionnaire and interpretation of results, and Dr Hywel C Williams for critical comments on the manuscript.