Preventing the spread of maedi-visna in sheep through a voluntary control programme in Finland

The sheep disease maedi-visna (MV) was introduced into Finland in 1981 and had spread to eight flocks in the southwestern part of the country when fir st detected in a survey in 1994. Six more seropositive flocks were subseque ntly traced, bringing the total to 14. MV has a notifiable disease status i n Finland that provides for official restrictive measures to which all infe cted herds are subject. These measures are withdrawn once the seropositive animals and their progeny are culled and the flock has showed negative sign s in the test done twice, or after total culling. A voluntary control progr amme was initiated in January 1995 to extend official control efforts. The programme furnishes a guideline for culling, restrictions on contacts, and a timetable for testing the flock to attain MV-free status. Seven flocks of the 14 were slaughtered either immediately or after a period under restric tive measures. One flock finished sheep production after four years under r estrictive measures. Selective culling and repeated testing was attempted w ith the other six flocks, three of which attained MV-free status. One flock finished sheep production after two years in the control programme, the ot her two dropped out of the programme when the restrictive measures were wit hdrawn. It was concluded that the control programme was salient in eradicat ing MV from Finland and that serological monitoring of the situation must b e continuous. (C) 2000 Elsevier Science B.V. All rights reserved.